Solar Cell Achieves 40% Efficiency

Fysiks Wurks found on the U.S. Department of Energy website news of a breakthrough in solar energy efficiency. From the article: "...with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance." A page linked from Wikipedia's article on solar energy calculates the land area that would need to be covered by solar collectors at 8% efficiency to meet the world's energy needs (using 2003 figures). At 40% efficiency, it looks like a square 265 miles on a side in the American southwest would do it.

Comments

transport losses?

[toQDuj]

yes, a few hundred miles in the american southwest would do it (anyone objecting to using Texas?), but only if the entire world lived in the american southwest. As it is, energy losses due to transportation are quite significant and hinder an all-out world power source plan.

B.

Re:transport losses?

[dew-genen-ny]

When you say energy losses due to transportation, are you just talking about transmission over wires?

How about conversion to something like hydrogen?

There are lots of desert areas that I'm sure could be used for energy generation, at least it would be better than polluting our way to global death....

Re:transport losses?

[nicholas.]

And yet somehow we have no problems tranporting oil to non-oil producing regions. A huge solar farm could produce massive amounts of hydrogen. And hydrogen transports just as easily as oil via the same infrastruture. Cheap, unlimited, nearly clean energy and all we have to do is build it. I bet (no figures nor money to back me up) that we could have built several solar farms for the cost of one war in Iraq --not that I'm getting the two issues confused ; )

Re:transport losses?

[jtorkbob]

Hydrogen conversion has its own inefficiency, so that's out.

That statistic is simply an illustration in any case. Obviously there are some other places in the world where such installations could be put; perhaps some less sunny ones would require more space to reach equivalent capacity.

In any case, I think that a 100% solar earth is unlikely:

* Much of the time it is night, and storing that much juice in batteries is impractical. Things like hydroelectric storage and thermal solar plants could help with this problem, but its a whole different research issue.
* In the event of, say, a major volcanic eruption or meteor impact, world power production would plummet. That could be the least of our worries.

Solar and wind are like the icing on the clean power cake. They are great for the role they serve, but you can't have them for dinner without getting a stomach ache.

Re:transport losses?

[Anonymous Coward]

Great. You've been so brainwashed by the media measuring in Libraries of Congress or Size of Texas that now you are forced to convert into those units to understand a size.

Re:transport losses?

[Anonymous Coward]

And hydrogen transports just as easily as oil via the same infrastruture.

Bzzt! Wrong answer. Hydrogen requires a completely different infrastructure that has never been massively developed. Transporting hydrogen trapped in a hydrocarbon is feasible and could use the same infrastructure, but hydrogen itself is a much more complicated issue. You either need to cryogenic cooling or you need to build infrastructure that has low hydrogen diffusion and low hydrogen embrittlement (and probably very high pressure to move a significant energy density of hydrogen around if you go the gaseous path). People who want hydrogen for various industries tend to steam reform it from hydrocarbons instead of using this oil infrastructure you think can transport hydrogen.

Re:transport losses?

[poopdeville]

I think the best use for this technology would be to put it on every roof in in America (and Europe and eventually the world), and use nuclear power as a method to buffer against periods of low sunlight.

While the major volcano/meteor event you mentioned could deplete the nuclear buffer, it would do that (and worse) now.

At the very least, considering the effects on the economy that nearly free energy would have, we could build enough nuclear power plants to completely handle our energy needs in case such an unfortunate turn of events occured. Hell, we could sell of the surplus nuclear energy to subsidize projects like the complete mechanization of food production, -- obviously using our nearly free energy. Or just lower taxes (though I would prefer the former)

Re:transport losses?

[Anonymous Coward]

Mod parent up. He clearly knows how to achieve the technological utopia we all long for.

Re:transport losses?

[poopdeville]

And yet somehow we have no problems tranporting oil to non-oil producing regions.

We don't?

Wait, we do. And that's the prime economic reason developing alternative energy strategies is in the US's (and everyone else's) best interests, despite our reliance on our current profits in the energy market.

Re:transport losses?

[mubes]

With the exception of nuclear power we already have a 100% solar earth to all intents and purposes. It's just the conversion techniques that vary.

Re:transport losses?

[Basehart]

"Much of the time it is night, and storing that much juice in batteries is impractical."

Doesn't it say in the bible somewhere that it's a sin to stay up after the sun goes down? Regardless, maybe we could get back to a more wholesome existence and put a stop to all that late night fun I hear people having outside while I'm stuck here coding until I go crosseyed.

Re:transport losses?

[dbIII]

The big point with photovoltaics is you can stick a little panel just about anywhere and not worry about line losses or being on the grid at all - plus the lead time to set something up is very low - buy a panel and get an electrician to wire it up. The big problem with photovoltatics is it doesn't scale up - so for a really big facility you are better off with something that does like a thermal solution or very large water turbines if you are lucky enough to have somewhere to put them. Having a lot of cheap mirrors putting heat on some expensive photovoltaics gets halfway there.

If you are just going to put bare panels somewhere it makes more sense to stick them on the top of existing poles instead of in some big facility since they act as discrete units anyway. Once they get rolled out there really isn't much that has to be done with them - the photovoltaics that existed when Einstein was young probably still work.

Personally I think we are already seeing the start of one of the major potential uses for photovoltaics - appliances that don't have to be plugged into the grid. If the prices come right down things like solar mobile phone chargers may well become mainstream.

Re:transport losses?

[jtorkbob]

I think the best use for this technology would be to put it on every roof in in America (and Europe and eventually the world), and use nuclear power as a method to buffer against periods of low sunlight.

I agree that local micro power is another good peice of the puzzle. My number one goal in life is to eventually live in a home with a net energy surplus. Of course, my penchant for running Linux on old hardware might turn into a barrier to this.

While the major volcano/meteor event you mentioned could deplete the nuclear buffer, it would do that (and worse) now.

Well, given a 'minor' event like Mt. Saint Helens, light blocking would only be a minor concern to the overall energy supply as we have it now. Obviously ash and debris in equipment, supply chain interruption and so on would be another issue entirely.

Hell, we could sell of the surplus nuclear energy to subsidize projects like the complete mechanization of food production, -- obviously using our nearly free energy. Or just lower taxes (though I would prefer the former)

Well, that's a different question, one I hadn't considered too deeply. Still, until we develop a 'perfect' single energy source a la Mr. Fusion, there will have to be a wide variety of energy sources in order to have a stable energy system. Nuclear/fossil systems require finite and largely imported fuel. Wind, solar and geothermal require specific geography. Hydroelectric fsks up the ecosystem. Each has its place in the ideal system, however limited.

Re:transport losses?

[Eivind]

Sure. That's actually another *advantage* of solar.

It's a lot more practical to scatter a large numer of smaller solar-plants around than it is to do the same with nuclear, oil or coal-powered plants.

If you do this, for example, by installing them on the roofs of homes you get 2 extra benefits:

• It makes the house less hot. If 40% of the sun is converted to electricity, then that's 40% which is *not* converted to heat. Decreases the demand for AC.
• It produces the most power precisely on the days when the demands on the grid is at its peak. (assuming warm/sunny areas) Which, is optimal if your goal is reducing the strain on the grid.

Re:transport losses?

[Sique]

The best ones are the directly injected Diesel engines (like the TDI or HDI) with about 46%, then the directly injected gasoline engines (~43%). For a car you have to subtract the losses due to the transmission, the clutch and the tires, and you have to take into consideration that the engine runs most efficiently only in a narrow band of rotations per minute (around 40% of the max revs for four-stroke machines, about 70% of max revs for two-stroke machines).

Re:transport losses?

[buffer-overflowed]

Even the nuclear stuff is solar. Big matter crushing solar explosions of doomy doom.

Re:transport losses?

[Eivind]

True, if you had enough solar-power to cover the entire grid, and surplus in addition to that, then producing hydrogen for vehicles would be fine.

Aslong as you're doing less than covering grid-use though, you're better of with a storage-mechanism that wastes less, such as pumping water to a magazine higher up.

You can store substantial amounts of power. If your magazine is 400 meter higher than the powerplant, then each additional cubic-meter of water up there contains 1Kwh. Thus, for example, the Veltdalslake (western Norway) with a size of about 12km^2 and 25 meters of regulation, at 1100m can store on the order of 900 million Kwh -- which counts as a substantial battery in my book. :-)

Re:transport losses?

[Eivind]

But that's just non-useful pedantry.

At a large enough distance, all things are the same. Which removes distinctions which in real life are useful.

For example, the phrase "renewable energy-source" actually has meaning. True, one can claim that *no* energy-source is renewable -- because entropy will always increase, and for example solar-power is nuclear, and infact the sun is going to run out of fuel at some point.

Or you could argue the oposite; that pretty much all energy-sources are renewable; oil coal and gas come from organic matter afterall, so given a long enough time, there's no reason why they shouldn't renew.

But this is just playing word-games. You've told nobody anything new with this. We're talking here and now and on human timescales.

Oil won't renew -- in the next 10, 100 or 1000 years. So for practical purposes it's non-renewable.

The sun won't run out of hydrogen the next 10, 100 or 1000 years, and furthermore it doesn't run out any faster if we install solar-cells. So for all practical purposes, the sun is a constant source of energy.

Re:transport losses?

[JohnFluxx]

As opposed to the cost of electricity for the whole world over then next 30 or so years?

How much is the total electric bill for the world?

Re:transport losses?

[hcdejong]

Nuclear power is an inefficient method to create a buffer. You'll need to run the reactor at a significant power level to keep the steam circuit hot enough that you can start generating immediately. Starting up a cold reactor takes hours, so you're better off not shutting it down at all.
And even at low power levels, your fuel will keep fissioning merrily along, so in essence you're throwing away a finite resource. Also, your buffer will be significantly more expensive than the solar energy you're using as primary.

If you have an abundant source of renewable energy, you're better off using some of that to drive a buffer. Hydro buffer plants such as Dinorwig (see elsewhere in this discussion) have been shown to work well.

Re:transport losses?

[fbjon]

I can't remember what it's called, but Sanyo had some interesting futuristic plans for solar panels installed in the world's deserts (or similar places). Having them spread around the world would mean that power is available around the clock, with some converstion to other forms of energy of course.

Re:transport losses?

[Dilaudid]

Over history oil prices have been inversely proportional to growth in GDP. Hence the parent logically concludes that reducing the price of energy will increase GDP i.e. the economy will grow. The people in the power industry may lose jobs - however the enormous reduction in costs in the manufacturing sector (boosting say the automobile manufacturing sector), the decreased cost of electricity (air conditioning unit sales would take off), and increased household disposable income (lower bills) would compensate this for most people.

Grid power would fall in price - because a) there is reduced demand for it (everyone is using their own panels) and b) supply would increase (people can sell the excess electricity from their panels back).

Re:transport losses?

[Calinous]

Yes, you will need to put plenty of cable to transport energy half a world away (like from USA to Australia). While Australia doesn't use much electricity, USA does. In 2003, the consumption was 3,660,000,000,000 kWh. This is 10,000,000,000 kWh a day, or some 400,000,000 kW. How could you transport these? Well, 400,000 MW could go on a line at 1000 kV, for 400,000 Amperes average (as electricity is not used at the same rate, let's say max would be double - for hours at a time). Now, for power transmission you could use a 0000 AWG line. This gives: OOOOAWG 0.46 inch diameter 0.16072 resistance (ohm/km) 302 A current max How much energy could you transmit over this? 302A, you lose 50V per kilometer - half a world away, at 20,000km - 1000kV losses. On a line of 1000kV, all the energy you can pump goes as losses. How much copper such a line would have? At 100mm^2 sectional area (10^-4 m^2), the wire volume is 2000 cubic meters (or a cube at 12.5 yards across, for each of the wires How many wires will you need on the US end? Some 2,000 (to support double the average current) - for a 36 millions tons of copper. World copper production is in the 10 millions ton area, so you would need some three years of world production to build such line.

Re:transport losses?

[Columcille]

Tidal energy comes from our moon. You can thank the Mondochiwan's for waiting too long to align all 5 elements the first time. Bruce Willis hasn't yet waited too long the second time, we still have a couple hundred years for that.

Re:transport losses?

[Dr. Spork]

Realistically, I don't think that any nuclear station would need to have down-time. If the public grid was producing enough of its own power, the nuclear plant's energy would go to hydrogen electrolysis. After all, even in an energy utopia, we'll need energy in some sort of a transportable form - say for cars and rockets.

Re:transport losses?

[indifferent children]

Is energy really expensive enough to justify covering your house in solar cells?

Energy as we collect it now, has some non-obvious costs. What does pollution from burning fossil fuels cost us in terms of healthcare? What will sea-level rise cost us? (hint: NYC, LA, DC, Miami, New Orleans, Mobile, and others are very close to sea level, and those are just the US examples.) Would we really have spent $300B and 2,906 American lives (so far) in Iraq if we didn't need to "stabilize" the region that supplies most of our oil?

Part of every dollar that you pay in taxes, at the store, at the hospital, in fact pretty much everywhere, is an energy cost.

Re:transport losses?

[Lopton]

Yes you will keep fissioning at low levels, but it uses way less fuel. Core life is measured based the hours at full power, if you operate at a really low level of power you extend core life drasticaly. There are also many ways to maintain a plant in a stable, shut down condition to where it can be restarted quickly, the Navy has been doing this for many many years. The significant start-up times come when you have to cool the plant down drasticly for maintenance.

Re:transport losses?

[maxwell demon]

The problem with solar panels is PRICE. That is the nut that needs to be cracked. If a panel is only 10% efficient, but not much more expensive than a similar sized roofing slate, it suddenly becomes economical to re-roof the house the next time the roof needs attention. However, it's not even near that price. An 80 watt panel currently costs around GBP£250 which is fantastically expensive. There is no way I could even remotely afford solar roofing at those prices, however much I'd like it. The price per peak watt needs to be about a tenth of what it is now.
  According to the article, the new solar cells would cost about $3/watt. I don't really know the exchange rate between $ and £, but AFAIR it's about a factor of two. That would give £120 for an 80 watt panel. Still not 1/10th, but at least less than half the price.

Also note that in your calculation you also have to add the savings in electricity. That is, you don't have to have equal price to conventional roofing, but you have to have the equal proce of conventional roofing plus the saved payment of electricity in some reasonable amount of time. So if the money saved on your electricity bill in, say, the next three years makes up for the extra cost of solar cell roofing, it's still more profitable to do it. (Well, actually you'll also have to account for the interest you would have gotten for the money during that time, because the money you pay for electricity next year will still give interest this year, while the money you spent on the solar panel will not.)

Re:transport losses?

[maxwell demon]

Not all our energy is nuclear: Tidal power plants don't use nuclear power.

However it's quite obvious that the sun must be shut down as quickly as possible: First, as you aready said, it's using nuclear energy, and of course nuclear energy is known to be bad. But for the sun, it's not even abstract: The sun is known to continuously send radioactive radiation. Fortunately the earths magnetic field and atmosphere are saving us from most of it, but what if the magnetic field fails? Also note that we are already quite certain that the sun will end up destroying all life on earth when (not: if) it finally fails. So we really shouldn't tolerate such a dangerous nuclear reactor so close to earth. :-)

Re:transport losses?

[somersault]

Agreed. It is it the real cause of our 'global warming', and will eventually evelope our planet, turning our great,great,great,great,great,great,great,great[et c] grandkids into crispy pork. With the decline in moral values today they're bound to deserve it anyway, though, so maybe it's not worth the effort.

Re:transport losses?

[olyar]

I'm building a new house right now and will be putting on solar panels. Its an easy decision these days - at least in the part of California where I live.

I'll get about a quarter of the cost back in refunds from the power company right up front. The remaining cost (around $25k) will roll into my mortgage, which will increase it by around $100 per month (30 year mortage at 6%). My monthly electricity bills should be reduced by at least $150. It just makes sense.

The fact that I care about the environment just makes it an even better deal.

Re:transport losses?

[plopez]

I would reccomend Nevada as there are HUGE military reservations there. The only problem being is that the giant mutant ants love silicone panels. But I'm sure we could figure sometning out. :)

Re:transport losses?

[hcdejong]

On second thought, I don't think the fuel burn rate matters all that much. The operating cost of a nuke plant is determined mostly by other factors (cost of building it, personnel etc., EOL disposal of the reactor). Running a nuclear power station strictly as a backup means you won't sell many kWh which means your cost/kWh goes through the roof.

It's not a coincidence nuclear power stations are often run as a base load, running at 100% of capacity basically full time.

Re:transport losses?

[QuantumPion]

Not quite true. Lifetime on fuel rods is dependent on the number of fissions, not the time spent in the reactor. Control rods mediate the reaction or can shut it down nearly entirely. I have looked with "no joy" (unsuccessfully) for info on minimum power levels at nuke plants, my guess would be 5%-ish of maximum power just to keep the turbine spinning. There would also be some interconnect time if they're off-grid.

The minimum power a nuclear plant can produce electricity at is around 20%, but this is due to non-nuclear issues (turbine vibrations, steam quality, etc). As far as the reactor is concerned, you could theoretically run at 5% power indefinitely, however there are issues associated with running at less then 100% power for extended periods of time. What happens is that in order to run at low power, you have to use the control rods to control power level, but if you deplete the core with control rods in you create axial asymmetries.

Big nuke power plants are designed to be base load generating plants, running at 100% all the time. They are sensitive to making power changes on the fly and if you shut down completely, you can't go back online for a couple days due to xenon. However, there is no reason why you couldn't design a smaller reactor designed for peak loads or emergency use. It would work just like a naval reactor: compact, high power, and using highly enriched uranium.

Re:transport losses?

[jandrese]

Two things:
1 Manufacturing solar cells is currently an extremely energy intensive process, it also creates a startling amount of toxic waste. Solar Cells need to be replaced on a regular basis as well.
2. Solar Cells are extremely expensive. I don't know about these 40% jobs, but something tells me they won't be a lot cheaper than our current top of the line cells. We're talking about a project in the trillions of dollars to do what you describe.

Re:transport losses?

[QuantumPion]

This isn't quite correct. First, nuclear fuel doesn't get used up if it is not at power. The neutron flux at shutdown, compared to full power, is many orders of magnitude lower. The amount fuel is depleted is called the burnup, and is measured in gigawatt-days per metric ton uranium. Typical fuel is designed to last 40-60 gwd/mtu. If the reactor is at low power, the fuel will not be depleted at a significant rate. However, there are issues with running at low power for extended periods of time, this is because "burning" the fuel with control rods in causes axial asymmetry.

Second, power reactors can remain hot at zero power for extended periods of time (called hot-zero-power or hot-standby). In PWR's, the reactor is designed to operate at a certain temperature (usually around 580 degrees F and 2250 psi). The reactor cannot be operated at colder then 540 degrees or so, due to physics limitations (moderator temperature coefficient, thermal stresses, etc). The way PWR's initially heat up the coolant at the beginning of a cycle is by simply running the coolant pumps. The pumps that circulate the coolant are monstrous (~7000 hp) and can heat up the system to operating temperatures all by themselves. They also keep the water at hot conditions while the reactor is at zero power.

In a world powered entirely by solar panels, large nuclear power plants for use at night or in case of volcano would work just fine. This is because if they were needed, they would be operating at 100% as base load plants.

Re:transport losses?

[Tim C]

The best solution, at least in built up areas, would be to have the national grid fed by solar cells, rather than individual houses having them

And what better place to put them than on building roofs? Nice and high to help catch the sun and avoid damage/vandalism, and pretty much every building already has a connection to the Grid anyway. While you're at it, might as well route the power generated through the building's electrical system, feeding any surplus back into the Grid.

That way the big power companies hopefully swallow most of the cost of switching to solar power

One way or another, it's us that pays; it's very rare that a company simply swallows a cost like that. It'll be passed on to us in our bills, no matter what "lower prices than British Gas until 2008!" type promises they may make.

Re:transport losses?

[drinkypoo]

You don't need batteries if you just sell your excess power back to the grid. You don't get much money for it when you do that but you don't need to store it, either. Also, the beauty of that is that most of us use the most power at night, because most of us are gone during the day. At least where I live, in order to sell back power, you need a time-of-use meter anyway... If you have a time-of-use meter you get off-peak power at rock bottom prices because they want to encourage people to use it then, since they have excess power generation. Also in my area, getting a time of use meter is free, because again, they want people to be motivated to use off-peak power. All you have to do is pay for the sync converter (or whatever that unit is) to hook your inverter up to the mains and bingo! Of course you still have to upgrade your box and bring your wiring up to code, which as you point out, is a very serious issue if you can't do it yourself and is usually still pretty major even when you can.

Re:transport losses?

[Rei]

"On every roof" isn't necessarily a good idea. Up here in Iowa, we don't get that much sunlight compared to all of those in the desert southwest. Not that this makes solar panels worthless; I have some to run my greenhouse's vent fans, since they come on when it's sunny (and thus, when the greenhouse will be heating up). But for general energy consumption, it would take a major cost reduction from the major cost reduction that would make energy in the southwest profitable. Which may well happen eventually, but not soon.

As for the original poster's comment about a volcanic eruption distrupting energy supplies and using nuclear for backup, there are ways to deal with power loss: energy displacement. The cheaper electricity gets, the more the world will use electricity-intensive industrial processes -- for example, aluminum smelting (that is, to say, use of aluminum use would displace steel use). Such processes can scale output based on available power supply. If the price of energy leaps due to a shortage (say, from dust blocking out the sun), such industries will be economically forced to curtail their production until the dust clears, thus freeing up power for everyone else to use (aluminum prices would spike, and steel use would begin to take over). Long term light shortages would be more problematic, but short term wouldn't be. Not that I think the world ever would be completely solar powered, but I just felt I should point this out.

As for hydrogen production, there's a much nearer-term option that I find really keen: Honda's "Home Energy Station" concept. Basically, almost every home in the US has natural gas lines running to it. Currently, natural gas is the cheapest way to produce hydrogen, so producing as much hydrogen as you need, straight from your natural gas line, seems a reasonable proposal. Of course, this raises the question, "Why not a natural gas-powered car? Why waste the energy converting it into hydrogen?" Well, apart from the very high energy efficiency of using hydrogen in fuel cells, with Honda's system, the energy released in converting natural gas to hydrogen isn't wasted. The waste heat from the process fires your water heater, so it's an almost lossless system unless you're consuming large amounts of hydrogen and using almost no hot water.

Re:transport losses?

[Dare nMc]

The best solution, at least in built up areas, would be to have the national grid fed by solar cells, rather than individual houses having them

NO, get rid of that power robbing, terroist target, lightning rod, ice gathering, bird killing, people killing, expensive ass eye sore.

I don't know how many billions of dollars our federal government spends on that grid every year, but anything to minimilize thing would be sweet, even if it takes more energy to produce a solar panel than it ever produced (fairly certain it doesn't.) I still think it would be worth putting solar panels on every roof just to have a single delivery charge, and not a constant drain.

I do think having developments linked is still a good idea, but if the load can be minimized, then the losses, maintaince, EMI emissions will drop to nothing as well. In Tuson now we have self sufficient communities running from solar, and a central connection for load balancing (I assume a central generator/connection to grid is present as well.) So you can supply the surge loads if a AC, and refridge kick on while running the microwave, and TV. That would be covered by your neighbors solar who are out of town/at work, and yours would do the same for them when your out.

Re:transport losses?

[Grayputer]

I think the issue is:

Think in-city clustered 12 story apt buildings. A simple building, 1 apt per floor, say a 1000 sq ft apt. So we have 12 'stacked houses' that have a single 'shared' 1000 sq ft roof. So 1000 sq ft of roof needs to support 12 'houses' of energy. Unlikely. THAT'S why the grid comes in. In clustered/dense city dwelling environments, roof top energy generation will be insufficient to cover the usage. We'll always need a 'grid' in that environment. How we fuel/supply the grid may be debatable but the existance is required due to the space/environmental constraints.

Re:transport losses?

[Maxo-Texas]

Right off the top you get $29,000 from other oregon and city taxpayers to buy your system. In any state without subsidies, that means over THIRTY YEARS longer payout period. Most solar cells degrade substantially by 20 years (10-20% less power output). Likewise, I'm betting like MOST states, that not just anybody can get those $29k in credits in Oregan. There is probably a fairly limited budget (a few million) and once that is gone each year, there are no more subsidies until the next calendar year.

I'm unclear how I'm supposed to use Federal Depreciation if it is not for a business or rent house. Granting that I can somehow use it for personal income taxes tho... it sounds like it would be a deduction, not a credit. That would mean it would lower your INCOME by roughly $3 grand a year- which would mean it would lower your TAXES by $1 grand a year at most. That lowers your savings from $13,000 to $5,000. That means your system costs $8,000 more --- that's 10 years more to cover costs. So you are up to 16 years, using your figures, and assuming you are lucky/smart enough to be one of the people that gets the subsidies.

Using your figures, for the 40 some-odd states where we only get the federal credits, the payout period is longer than the likely lifespan of the item.

---

Now one thing we need to remember is this: Power is appreciating about as fast as inflation. That means your $813 bill today is going to be $1600 in 10 years and $3200 in 20 years. That works in your favor. It helps home buyers too. In 1995 my payment was $700 a month and rent was $655 a month. Today my payment is $700 a month and rent is $1100 a month. In 2015, my payment will be $700 a month and rent will be roughly $2200 a month.

---

No.. It's not just an inverter. If you are connected to the grid you need a special circuit box that won't allow power to flow backwards into the grid unless the grid has power. I think it is called a reverse switchback circuit breaker.

The inverter converts DC - > AC.
The charge controller keeps the batteries charged and cycled at the proper levels so they have optimum lifespan.
The switchback? circuit box (can't remember the name exactly) keeps your 1.21 gigawatts of power from killing electric company linemen.

---

No need to be insulting about the AC ideas. If solar power drops by an order of magnitude it is suddenly a very clever and reasonable way. $900 of solar power and a simple $200 window unit and you don't need to run your central AC during the day at all. No need to upgrade your electrical system. No need to have charge controllers, batteries, etc.

---

There are several companies on the edge of dropping the price by an order of magnitude. Two of them basically print solar material with nano-particles. If any of them succeed and solar power does drop to 10% of the current price and becomes unbelievably easy to install (picture unrolling a 50'x3' long strip on your roof that costs about $3000 and produces 1.5 mw of power during the day with no clouds and it has a plug on one end to hook to another strip- no panels, no sun tracking arrays- nothing to break- no cells to be corrupted by water leakage. cool stuff)

As far as the other things- I'm already using efficient appliances, have a programmable thermostat, added radiant barrier, and use florescent lights.

---

I'm pro solar power. It just isn't practical yet unless you can get other people to help you buy it through subsidies. That's only an option in some states.

Re:transport losses?

[AmericanInKiev]

I don't see a loss of jobs related to the adoption of solar energy (in consumption country). The losses would occur in oil-fields ie Venezuela, Saudi, Dubai, etc...

The new jobs created by the Solar energy (and Wind sector) thus far are on the whole very good jobs, and there would be more jobs in a renewable economy, look at the O&M component of these "Concentrator" systems. They have moving parts, they require education to install, and the jobs would be create in every state and county. Nuclear plants, by contrast create jobs with a high risk-premium, but they also create less jobs per kilowatt than any other electrical provider, as the plant size is bigger, and there are fewer of them generally.

AIK

Re:transport losses?

[Maxo-Texas]

You can't be sure that production of solar power doesn't have some bad side effect. Producing them now makes a lot of nasty shit. Dealing with them as waste may release unknown pollutants into the environment.

You can't be certain that global warming won't produce a net gain of usable land.

You can't be certain that money *WASTED* on solar power today couldn't be spent much more effectively in a few years when it drops an order of magnitude in price.

You can't be certain that the average house price maintenance cost will be higher.

You sound to me like you have a religion of environmentalism and you need to realize that you have a lot of attitudes that you can't be certain of. Over the course of 30 years that I remember, I've seen a lot of people REALLY SURE and REALLY UPSET about FACTS that we now know are bullshit. COMPLETE BULLSHIT. So get off the high horse.

Re:transport losses?

[Rei]

Methane reformation releases CO

Carbon monoxide is highly flammable. It has the same NFPA rating as diesel (2). Burn it, recapture the energy. With a good countercurrent heat exchanger, you approach 100% efficiency. You can never reach 100%, and eventually it's not worth the effort to try for more, but you can get close.

It's less efficient than burning all of the natural gas to heat your water

Of course it's less efficient than burning the natural gas when you only consider the heat; you're getting hydrogen, too, and that's where part of the CH4's energy ends up. Burn the carbon monoxide, and your net result is:

H2
CO2
Heat

"Wasted" energy will end up as heat. Yes, there will be no perfect heat exchanger (which is why I said "almost"), but countercurrent heat exchangers can do a very good job.

A large solar collector would also..

[nullchar]

A large solar collector would also shade the ground and absorb the heat (energy) that the surrounding ground and air would normally receive. I guess, taking extra heat (energy) from one place, and adding it to lots of others may not be bad...

What about the cost in sending that energy down the wire? Would it be best to build one big-ass solar array? Or would it be better to distribute smaller collectors over a large area, even if the sunlight is not optimal?

Re:Cost is the issue

[GreyPoopon]

Very nice, but I'd rather see a reduction in cost per watt than an increase in efficiency.

By reducing the number of solar collectors needed or the area that needs to be covered, the installation costs are significantly reduced. The article indicates that this new technology could yield systems with installed costs of as little as $3 per watt.

Re:Cost is the issue

[rgravina]

I'd rather see a reduction in cost per watt than an increase in efficiency

Aren't the two related?

Also, FTFA:

This breakthrough may lead to systems with an installation cost of only $3 per watt, producing electricity at a cost of 8-10 cents per kilowatt/hour, making solar electricity a more cost-competitive and integral part of our nations energy mix.

where the facts?

[Anonymous Coward]

So it's a bit unclear what the article means by 40% efficient as the article seems to confuse the concentrator part of the solar cell with the multi-junction part. The concentrator doesn't make the device more efficient at converting solar radiation into electrical power, it just concentrates the light so you don't have to use as large of a device. The idea being that the solar cell material is expensive but the optics are relatively cheap, so you might as well focus as much light on the device as it will absorb and still function.

The multi-junction part comes from the idea that you can, using a solar cell, only extract as much energy from a photon as the size of something called the band gap of the material that the cell is made from. At the same time, a solar cell can only absorb photons with energies higher than the band gap. If the bandgap is small, as it is in silicon, then you can absorb most of the suns rays, but you can only get about 1 electronVolt of energy out of each one no matter how much energy the photon has. Since the bulk of photons emitted by the sun have more than 1 electronVolt of energy Si solar cells waste alot of the energy in sunlight as heat. If you make the solar cell out of a semiconductor with a larger bandgap then you absorb fewer photons (more of the solar spectrum lies below the critical energy for absorption) but you extract more energy from each photon. So, for a solar cell made from one material there is a sweet spot in terms of the bandgap that maximizes the energy extracted. Multi-junction cells try to overcome this by combining multiple devices with different bandgaps so that you can maximize both the total number of photons converted to electricity and the energy extracted from each photon.

Re:where the facts?

[swebster]

The concentrator doesn't make the device more efficient at converting solar radiation into electrical power, it just concentrates the light so you don't have to use as large of a device. Actually, that's not quite right. Higher light intensity does make the cells more efficient. It's one of the advantages of using concentrator cells.

Re:where the facts?

[YourMoneyOrYourDuck]

Can't you use a prism to split out photons of different energies and direct them at the appropriate receptor?

Re:where the facts?

[jannic]

What kind of facts do you expect from an article which contains units like kilowatt/hour, instead of kilowatt x hour? That really looks like the author was only interested in economics, not in scientific facts.

Re:where the facts?

[frostband]

I was really hoping they would (but knew they wouldn't) link to a specific journal article about the devices being used. If anyone knows if this group has produced a scientific article (IEEE, AIP, etc...), I would appreciate a link. I did a quick IEEE search on multi-junction solar cells and didn't find anything about the device mentioned in TFA.

Re:where the facts?

[frostband]

It's not necessary to do it that way. The way these multi-junction cells work is you have several layers of different semiconductor materials (with varying band gaps as the parent said). The material with the largest band gap is on top and the band gap of the material decreases as you go down the layers of the device. If a photon is not absorbed in the first layer (meaning the photon doesn't have very high energy, since, as the parent also said, the photon must have greater than the band gap energy to be absorbed), then it continues on to the next layer to be absorbed, then the next layer. This way, you are extracting the maximum amount of energy out of each photon.

That isn't a perfect explanation and any experts out there, please correct anything that's wrong.

Downsides

[ChowRiit]

I'm all in favour of clean energy, I think it's a laudable goal, but we shouldn't be patting eachother on our backs just yet.

Firstly, these solar cells are no doubt incredibly expensive - any high efficiency ones are. Secondly, they're probably made using rare and/or exotic materiels, making manufacturing in bulk tricky, and thirdly there's likely to be a lot of pollution created in the manufacturing process for by-products et cetera (it's a problem with less efficient cells too, but the more efficient ones are generally more pollutions).

Lastly, there's another issue. What happens when the sun goes behind a cloud? You need to be able to cover the entire slack in an instant, because you NEED a constant power output. That means you NEED enough GAS powerplants to power the whole world too, as they're the only type of power plant you can literally turn the dial and turn up the output.

Me, I'm going to be sitting here hoping that the test fusion plant they're building in France works, because from what I've learnt lately, if it doesn't, we're screwed.

Re:Downsides

[Atlantis-Rising]

Er, ever heard of batteries? It's perfectly possible to have capacatance stations built into the grid that serve as temporary UPS units for when the power slacks. Similarly, if you spread the generating stations out roughly evenly around the planet and build in enough extra capacity, (maybe 5%, I'm talking out of my ass here) the chances of cloud covering enough of that generator grid to cause a severe power loss are probably negligable.

Presumably, you'd want the capacitance spread out across the grid- not only to prevent brownouts due to lack of power production, but also to temporarily handle spikes in load and to handle temporary grid failures. Neighbourhood or even house-scale capacitance units wouldn't require much storage and could effienctly handle temporary spikes in load, like the use of (for example) a microwave or vacuumn cleaner.

Of course, if you're splitting up capacitance that way, why not split up generation that way too? Just use the power grid as a way to ship excess power around to handle temporary generation losses.

Energy from the sun at maximum potential is what, 1 KW per square meter? My house's roof is probably 15-20 square meters; 12 KW on a sunny day is great. I have absolutely no idea at the moment how much power I'm actually using, on average, (including nights, etc) but I'll bet this won't be enough to cover it. That's okay. Even if it covers half of it...

Re:Downsides

[hcdejong]

That means you NEED enough GAS powerplants to power the whole world too, as they're the only type of power plant you can literally turn the dial and turn up the output.

No, they're not. Hydro plants can do this as well. The UK uses several hydro plants like Dinorwig to cover peak loads. Dinorwig can go from 0 to 1320 MW in 12 seconds, and has a peak output of about 1800 MW. It is built as an accumulator system, pumping water up the mountain at night (using excess capacity from nuclear and fossil fuel plants) so it doesn't depend on a huge water supply (river). Efficiency (W generated vs. W needed to pump the water up the mountain) is about 70%.

Re:Cost is the issue

[Rinikusu]

Erm.. deserts are empty.. of what?

Lots of animals and wildlife flora/fauna live in the deserts. Many of which are endangered. Many of which provide valuable eco-service to the land around them. It might not be prudent to just blot out the sun with solar collectors and think everything's going to be okay.

I'd rather see these on rooftops, supplementing power sources in a more local fashion where their impact will be minimal.

Re:Cost is the issue

[dch24]

In addition, 40.7% is just a bump up from 39%, which (apparently) Spectrolab has been achieving for the better part of the year. They may be very close to high-volume production. Direct photovoltaic solar generation is an immediate revenue source, but solar energy can be directly applied for other processes, the most notable being desalination.

Panels On The Roof

[DaftShadow]

I've been recently wrestling with the idea of putting solar panels up myself, but the truth of the matter is that I cannot afford the current RoR's length of time (approx 13-18years), nor can I get enough panels onto the limited rooftop I plan to use to cause a very big dent. A huge increase in efficiency of space, as well as cost/watt, changes these numbers *dramatically.* This is awesome.

- DaftShadow

Re:Panels On The Roof

[Nasarius]

Contact your local power company. Many (such as LIPA) will pay for a large percentage of your costs.

Re:Panels On The Roof

[jez9999]

What I do, in SimCity 2000, is build a few hills. Then, I apply 'water' to each tile of the hill, and build a hydroelectric damn on each one. Best form of power by far; no explosions, breakdowns, and lots of power per square.

Hmm. Wonder how realistic this is. :-P

Still does not solve much

[WindBourne]

The issue is not one of generation. There is actually plenty of energy production (and more is coming on line with new wind and geo-thermal). Our problem is one of energy production when it is needed. Since solar (and most alternatives) will NEVER be able to produce 24x7 or even 8x7, then you need a way to save the energy. As it is, USA feds has been trying to force more research down the path of hydrogen. But the earliest will be around 2025 ,and that depends on having some MAJOR advancements in cost economics that make this solar cell efficiency games look like child's play. IOW, this route will not be happening.

Do not get me wrong. These solar cells are most likely a good thing. Of course, it depends on how the true cost relative to other methods. But this country needs to quit subsidizing oil and coal as well as have a multi-prong research in energy storage to really make the alternatives happen.

Re:Still does not solve much

[magman]

You've got it completely wrong... One of the main benefits of the solar production is that it's distributed and produces during peak hours. In other words, the power is generated when it's needed and you don't have to transport it to the areas where it's being used. Think air conditioning In Japan it's already cost effective to install solar panels without subsidies, in other parts of the world you generally need subsidies to get it working economically. But this business is growing at a rate of 40% each year worldwide, it's only a matter of time!

Re:Still does not solve much

[stile99]

Isn't it amazing how a stupid show from the 80's can blow your theory right outside of the water?

I refer, of course, to Automan. A crime-fighting hologram who only worked at night. Why only at night? Because the power grid maxed out during the day. There wasn't enough power to operate the hologram during the day because everyone woke up and turned on toasters, microwaves, fans, A/C as the temperature rose, etc.

They point being (and this point is so obvious that as I said, it was made by a dumb show over 20 years ago) is that solar does very much indeed produce when needed.

You are absolutely correct...solar panels on the rooftop aren't going to produce 24x7. What you don't understand is the power curve throughout the day. Those solar panels are going to start pumping out energy about the time you turn on your toaster, microwave, dishwasher, etc.

God, geeks are so incredibly stupid

[Anonymous Coward]

1. Deserts are not empty. They have an ecosystem.

2. There is no reason at all to fill a desert with solar cells, and then transport the energy across to the other side of the planet. Solar cells are installed locally, like on your roof, or in your back yard, on every roof across the planet. Most of the electricity consumed would be as Direct Current right from your rooftop, with an inverter converting for those appliances you still insist on retaining that us AC.

3. For dense city sitatuions with high rises who's energy needs can not be met by rooftops, etc., electricity can be sent via conventional AC lines across the conventional power grid from say no more than 50 miles away. Not the other side of the world.

4. Those who produce an excess of electricity beyond their need, sell it into the grid.

Re:God, geeks are so incredibly stupid

[X]

1. Nobody is implying they don't have an ecosystem. If you consider the amount of damage being done to ecosystems to provide the world's current energy supplies, entirely destroying 265 square miles to provide the world's energy would be an improvement.
   
2. I don't think anyone sane was suggesting all the world's energy actually be produced in one place. It just provides people with an idea of the minimum amount of land needed if the whole world used solar energy.
   
3. You can do better than 50 miles (keep in mind that states in the western US provide a lot of power for California, and you know that a chunk of that energy is being burned along the California coast), but yeah, you don't even think about sending it to the other side of the planet.
   
4. Well, if you're limited to 50 miles away, that kind of limits one's ability to sell power on the grid eh? ;-)
   

And That...

[Belial6]

"Lastly, there's another issue. What happens when the sun goes behind a cloud? You need to be able to cover the entire slack in an instant, because you NEED a constant power output. That means you NEED enough GAS powerplants to power the whole world too, as they're the only type of power plant you can literally turn the dial and turn up the output."

And that is what fuel cells are really for. Forget having hydrogen delivered to your home so that you can use a fuel cell as a generator. No, you use photovolic at the home to generate a tank of Hydrogen so that you can convert it back to electricity when you need it. The real promise of fuel cells is for use as a very clean battery.

Re:Cost is the issue

[mrbluze]

A viable business model for the solar energy solution might be for new houses to be built with high efficiency solar arrays on rooves, using the energy for household purposes and selling excess energy. Therefore a return on investment could be expected. Excess daytime energy can be stored for night-time use, though this is fairly inefficient (the most efficient method is pumping water uphill to a dam). In places like Australia this is quite achievable, as governments have been fairly forthcoming at times with giving grants and subsidies to people taking up environmental initiatives, and on the other hand issuing strict regulations for energy saving methods of house design. With the prices of electricity which exist in Australia, for example, it's actually a very achievable aim - with a $10,000AUD outlay for a regular household solar array, recouping the investment occurs in about 10 years. I don't think having solar farms is the only solution - only the big business solution.

Re:Cost is the issue

[WindBourne]

So now, you are suggesting that we should put all of America's power generation in exactly one small spot. Yes. Oh yes. I can hear it already:

there is our next target with the new bomb (thank you, george), the Americans make it sooooo easy. .

In addition, as to farmland in the desert, well here is a couple of thoughts:

• There is actually too much unproductive farmland in America. We have a lot of land that is actually very poor, but still in production due to farm subsidies. And desert land is very nutrient poor.
• Here in the West, and more so the SouthWest, we have this issue with water. We are lacking. Plan on sending some our way? We could use it more for our pools and golf courses. And yes, the city folks, esp those from back east, will demand that the water go to them.
• A simple fact is that plants need light. The solar cells use what? Why light. And they all have a back that reflects the unused photons back through the layer so that it might get another chance at being used.

Re:Cost is the issue

[glittalogik]

They're only related if the more efficient panel isn't significantly more expensive to produce. That is, of course, largely a matter of demand; the more of something you want/make/buy/sell, the more refined the production process becomes and the cheaper the individual units become - in this case, solar panels and therefore kilowatt hours.

Frankly I'm in favour of biting the bullet and making this a personal routlay, and am looking forward to doing so when I have a property to do it to. If someone can afford to buy a house, they can afford to put some bloody photovoltaics on the roof and if that adds an extra 6 months to their mortgage then so be it. For once it'd be nice to see economics take a back seat to environmental responsibility.

Re:Here's an Idea

[MichaelSmith]

How about we build a ring or spherical grid of energy-collecting satellites around the Earth?

Its not exactly a new idea.

Re:Cost is the issue

[bogjobber]

Looks like someone needs a refresher course in ecology. Deserts are very rich and diverse zones. Remember, a desert isn't just sand dunes. Just because it isn't green and not many people live there (the US West/Southwest) doesn't mean it's a barren wasteland. Also, the reason why the desert isn't farmland is because there is no water. The thing preventing Nevada from being a rich agricultural region is a rather large mountain range, not too much sun. Unless you can find a way of getting more water to the desert (like the Northwest) then it isn't going to produce squat.

Besides, other areas of the country still receive sunshine. I bet when you take into account the costs of maintaining the transmission infrastructure as well as the risks associated with a centralized power source most of the solar stations would be stationed near population centers instead of concentrated in one area.

Figures a bit out

[tttonyyy]

According to this site, estimated world demand was 13.9 trillion kilowatt-hours in 2001.

13.9 trillion kW/h / 8776 (hours/year) = 1.58TW

This figure is comparable to the statement in the wikipedia that 2001 average world consumption was 1.7TW in 2001. So our sources agree within a reasonable margin.

According to the wikipedia, the energy density from solar energy reaching the surface as a global average is 170 W/m2. At 40.7% efficient, that's 69.2W/m2.

Using the lower figure of 1.58TW calculated above, you'd need 22.8 x 10^9 square meters, or approximately 8800 square miles of solar cells to meet 2001 world demand. (Or "just" 1900 square miles to meet the peak US demand of ~3 trillion kWh in the late 90s). Of course, these areas halve if sited in an area of the US where the solar energy density is 375 W/m2 (4000 square miles for world demand, 860 square miles for US demand).

Neither correspond to the whopping (265x265) 70000 square miles the article summary claims. Sorry kdawson, looks like you're a magnitude out!

Re:Cost is the issue

[hankwang]

It wasn't all that long ago that the electricity needed just to melt the silicon was more energy than the cell would generate throughout it's entire lifetime (they do degrade over time).

I don't know about how long ago you are talking, but the Energy return on investment varies between a factor 4 and a factor 17 for current solar cells, rather than a number below 1 as you are suggesting.

Re:Cost is the issue

[Big Nothing]

"Very nice, but I'd rather see a reduction in cost per watt than an increase in efficiency. It's not like there isn't enough space for for solar cells. Most of the deserts are rather empty."

I'm sorry, but this should never have been scored insightful. Its obvious at best, troll at worst.

First of all, improved efficiency reduces the investment cost, thus reducing the cost per watt (at least in a proper market economy, which the energy market unfortunately isnt).

Second, COx emissions are not the only environmental threat. In time, studies will more than likely show that covering vast areas of land with shadow-inducing plates (such as solar plants) has a negative impact on local and perhaps regional eco systems. More efficient solar panels mean less land area covered by solar plants, which is a Good Thing ®.

It never seizes to amaze me how people fail to look at the big picture;
* new cars emits less Cox and NOx, but the production of new cars is a significant ecological strain
* biofuel is great in small scale, but greatly reduces the ecological diversity and might pave way for invasive species
* solar plants might provide all the power the world needs one way, but at the cost of placing vast land areas in shadow

Etc.

The harsh reality is that there is no quick fix, there is no gratis lunch.

Re:Cost is the issue

[catprog]

Current energy cost to manufacture solar cells are about 1.8 years now

Gallium Nitride

[GanjaManja]

A student at The Univ. of California, Santa Barbara just presented research showing the use of multi-junction devices using Gallium Nitride. This is awesome because Nitride materials are very well suited for a HUGE amount of the sun's radiation, and since he managed to perfect a way of sticking several layers of differently absorbing Nitride Materials together in ONE device, we could theoretically see solar cells that absorb the Entire spectrum of the sun's rays in the near future!

Here's some links:

Indium-Gallium-Nitride can be made to absorb the entire spectrum of solar rays:
http://www.lbl.gov/Science-Articles/Archive/MSD-fu ll-spectrum-solar-cell.html

Tunnel Junctions - this is how you stick together many different layers of material, each layer with their own optimal absorption range (in terms of wavelength, aka. color):
http://www.hitachi-cable.co.jp/ICSFiles/afieldfile /2005/11/28/review07.pdf
(sorry, this is the best I could do, there was no simple paper explaining a tunnel junction. "tunnel" is for electron tunneling...)

In essence, you have different layers that absorb only one range of wavelengths (colors of light), and whatever isn't absorbed goes straight through, and the next layer absorbs another range, etc. etc.

As an aside, did you ever wonder how blue LEDs & lasers finally managed to get working? Nitrides paved the way for emission (and absorption) in a range of visible wavelengths, including blue. This is also why they're great for this application.

Why is there a need to transport?

[kiddailey]

Why not just start making it mandatory for every high-rise and large-roof building structure to be covered with a certain percentage of solar cells that power part of the building during the day and feed the rest back into the grid? After all, the concrete and steel aren't doing anything with the sun.

It seems to me that if we had started doing this years ago it may have a) reversed some of our energy problems and b) potentially made solar panels more affordable so I could cover my home's roof with them.

Re:life span

[BlackPignouf]

You're not the first one to ask this question, and I won't be the first one neither to give this link:
http://en.wikipedia.org/wiki/Photovoltaic?section= Energy_return_on_investment#Energy_return_on_inves tment
I tried to calculate energy payback-time for different cells, and got results ranging from 8 months to 2 and a half years.
Even extreme PV-Cells bashers don't succeed in proving that payback-time exceeds 5 years, which still lefts you 3 times as much "free" energy.

Bright Future

[sam0vi]

I see a bright future for Middle East countries. If i were them i'd be investing now on solar cells before they run out of oil. Imagine the whole arabic peninsule covered by 40 or 50 percent eficient solar cells. I only wish i had a billian euros to invest

Re:Cost is the issue

[Eivind]

It was quite some time ago. Today, a solar-cell produces 4-17 times as much energy over its useful lifespan as is spent manufacturing and installing it. That's decent, and the number is climbing steadily. It's time to let that old worn-out argument against solar die.

Good point "National Security"

[kotku]

A decentralized power generating system is good for national security. Imagine that every house had solar generating capacity. There could be a guaranteed minimum power capacity per house. Sure, the system would be degraded in the event of the base supply being knocked out but supply would be enough for critical services that people rely on, heating, cooking, water pumping etc. It may take a long while for the base supply to be re-integrated in the event of a coordinated strike/failure against public utilities.

In Australia a few years ago there was a major disaster in the gas supply system that took a whole season to fix. The entire southern region was without gas for heating and cooking for weeks. Luckily the electricity system was still operational but a simultaneous failure would have resulted in a calamity.

Thermal is slow to start - but you can be prepared

[dbIII]

Actually - that's not true at all. Coal fired plants using pulverized coal can do so

It takes quite a few hours to build up steam from a cold start and it wears everything out quickly by thermal fatigue if you have a lot of restarts. What does happen is something called spinning reserve where coal is being burned and the turbines are spinning but the generators are not connected. The generators can be attached by a very large clutch and more pulverised coal can be fed in to bring things up quickly - I'm too out of touch to know how quickly now and worked in new plants of an old design. With hydro you just turn on the tap and things happen quickly - thermal needs time (which includes oil and nuclear too for people who forget that nuclear is stream power).

Anyway - the troll way above was doing the "one true energy" thing which you only get from idiots or salesfolk. Just becuase photovoltaics are not a drop in replacement for every base load power source on earth does not make them useless. In remote areas they have proven themselves for decades.

PROGRESS WE BE SCREWED!

[brunes69]

Yeah.

And what about all the buggy whip makers!

Who is thinking of THEM!

Re:PROGRESS WE BE SCREWED!

[Silverstrike]

Solar cells will come down in price too, of course, and presumably get more efficient.

Yea, if only they could manage that! We could have a spirited argument on Slashdot article about it!

vandals could easily damage your solar cells

Well, when they're making them more efficent (sometime in the future, obviously), they could also work on making them indestructible as well! Like my windows.

They'd also become less efficient over time and likely just need repair from general aging problems, and in the end you're probably losing more money than by using national power.

Yes! Obviously they'll go bad, because everything has a short lifespan....ya know, like my house's foundation. It's only got 6 months left!

Ok, ok, enough of that. Seriously though. Did you read the SUMMARY? Did it even occur that maybe you should look up the lifespan of a solar panel before MAKING UP statistics? (40+ years, according to a cursory Google Search for "solar panel lifespan"

Please stop, its just painful.

Re:Cost is the issue

[Alioth]

At current prices, you'll need a little more than 6 months on your mortgage. Assuming you're in Britain, which by the usage of your language is probably reasonable...

I bought an 80 watt peak solar panel in the summer, basically as a fun project and to investigate the practicality of generating some of my own electricity. Here is how it works out, using a monocrystalline panel (the most efficient panel commercially available at present):

Peak power is produced only within about an hour or so each side of mid day on a bright, cloudless, hazeless sunny day.
Three hours before or after mid day, the unit produces about 50% of peak.
Five hours before or after mid day, the unit produces around 10-15% of peak
At mid day, summer time haze with 10 miles visibility will cut output to around 80% of peak
At mid day, with thin cirrus clouds (still bright sunshine), output is around 50%
At mid day, on a bright cloudy day where shadows are still cast, output is around 15%
At mid day, on an overcast day, output is generally 5% or less.
In the winter, I've never seen the unit capable of producing more than about 25% of peak on the brightest winters day.

All in all, the average output even in the summer will only be 5% of peak (because of night time, and cloudy days). Winter time is even worse. So if you want to make sure you have an average of 200 watts - which really isn't a lot, but if you can store it or put it back on the grid it'll make your house more or less neutral in terms of the electricity you use, if you have the normal domestic cycle of being out and not using much electricity during the day. To get that average of 200 watts, you'll need 4000 watts peak of solar panels.

80 watt panels cost (in quantity) around £250 a piece. That'll cost you £12,500 *just* for the panels, without a grid tied inverter and storage system or installation (probably another 4 to 6 grand) - to get a measly average of 200 watts - i.e. just enough to power one Pentium 4 computer continuously. It's simply not worth doing at all unless you can put it back on the grid (not many electricity companies let you do that - yet), or store it in batteries - since if you have a normal domestic cycle, while your solar panels are producing near peak you will be away from the house and letting three or four thousand watts go wanting. You'll probably need three grand's worth of batteries if you can't sell back to the grid - and even deep cycle leisure batteries are going to need replacing at least once every 10 years. This is for a system which will only work reasonably well in the summer. In the winter, when the days are short and you need the most power, it'll hardly contribute anything - perhaps you'll get 50 watts average from £12,500 worth of solar panels.

If solar panels were 1/10th of the price they are now - yes, it'd be worth it. I'm waiting for the breakthrough in price, not efficiency (if the efficiency brings the breakthrough in price all the better). Even a moderate sized south facing roof - I've calculated just my shed roof replaced with solar panels could produce 1kW peak - is large enough for a decent peak output using current monocrystalline panels. Price is everything. If I could get the panels at 10% of what they cost now, you bet my shed roof (my only south facing roof) would be covered by the spring. But at the current price point? It's simply not affordable for the meagre amount of electricity you get. It's a shame because the panels aren't visually intrusive and they are silent and almost maintenance free, unlike wind turbines. I really really want solar panels to be worthwhile - but at the moment - at current prices, they simply aren't.

No streaks?

[maximthemagnificent]

>> At 40% efficiency, it looks like a square 265 miles on a side in the American southwest would do it.

Buy windex stock now, that's all I'm saying.

Grandpa was a Buggy Whip Salesmen

[maggard]

Actually, my Grandfather was a buggy whip salesmen.

After returning from The Great War, WWI, he was disabled (indeed he'd been declared dead & in the morgue at one point - mustard gas.) The job he could get was selling buggy whips, and his territory was the US Midwest & Canada. He was away from home for long stretches of time, and as you can imagine had some pretty amazing tales to tell of traveling to remote ccommunities back when travel was HARD.

However he saw the car taking over and once he'd saved up enough money he did the smart thing: Opened a service station.

Later it went bust in the Great Depression. He then started again, in putting in power lines, then power plants, and eventually became VP of a a large construction firm and responsible for many of the major structures still standing in Kansas City including the Liberty Memorial, Nelson Gallery, and the Starlight Theatre.

The point is, he really was in the buggy whip business and when the new technologies came in he adapted and took advantage of them. Then when the bust came he reinvented himself again and took his skills and when into an entirely new career. Not a new high-tech story, rather from a fella raised in a sod hut in the Oklahoma Territory where buffalo were a constant threat.

Re:Grandpa was a Buggy Whip Salesmen

[anvilmark]

Thank you for so graphically describing how a small % of people can come to own the vast majority of the world's wealth, the subject of another discussion.
Circumstance dealt him a series of "losing" hands, but he didn't bitch and moan and expect someone else to "make it right". He worked, very hard I'm betting, and became wealthy.

Based on what's I've read in that other discussion, he must have been a very wicked and greedy man.

I salute him.

Hello terrorist target

[yetanothertechie]

Good points in parent post. Here's another...

Of course you'd never want to put all of the collectors in one place...a few well placed munitions or a nuke from some rogue regime and there goes our power. Pretty effective way to incapacitate the nation, or throw the world into chaos if the power was being supplied throughout the world. Ever heard of offsite backup? Same principle. The collectors would have to be spread out in case of attack or natural disaster.

Wait, I can handle this.

[Grendel Drago]

Employee: Four pounds of grease ... that comes to ... sixty-three cents.
Homer: Woo-hoo!
Bart: Dad, all that bacon cost twenty-seven dollars.
Homer: Yeah, but your mom paid for that!
Bart: But doesn't she get her money from you?
Homer: And I get my money from grease! What's the problem?

Weather, TOC, etc..

[uncledrax]

I pretty much just picked a comment here at semi-random to talk about.

Keep in mind a few things when people are talking about 'solar paneling a roof'..

- Here where I live, we have a ton of pine trees.. they dump a ton of pine needles on my roof. I'd say at peak, almost .25-.3 of my roof can be obscured. That == instant cut of service.. obviouslly, i'd have to clean my roof more often.. are solar cells safe to walk on and do they stand up to abrasive brooms without degrading the surface quality?
Obviously the same would apply to Snow until it melts off (which takes how many hours during the day, of which you're getting far from peak efficiency from your panels with?
When it hits the rainy season, you have similar issues since your typical week is overcast?

- Reflecting the suns heat is desirable in the warm months, but not in the cold months. Currently I count on the sun during the day to help heat my house in the winter. If I panel my house with the same goal of attempting to collect/reflect all that sunlight during the summar to save/run my AC, I also have to run my heater more often because my house doesn't warm up?

- what the TOC on solar panels anyhow? I fully realize that the cost of replacement will go down as demand and technology increase.
I can get 10+ years from my current roof.. how often do solar panels need replacing? keep in mind they will be getting hit by (branchs | snow | heavy rain | leaves/pine needles | occasional base balls | people walking on them to clean them | cleaning chemicals | other forms of harsh weather such as hail and/or debris in hurricanes, etc..). Someone throw me some real-world numbers here?

I'm not trying to be a neigh-sayer, just trying to keep people aware of the every-day issues associated with such things.. i'm far from an expert on solar paneling, but these are some things that 'average joe' will want to know. And lets face it.. if you want it to get wide-spread adaptation, you gotta get the 'average-joe' vote.

Re:Cost is the issue

[James McP]

Different scale, purpose, and intent. Not everyone can jam a 70' tower in their yard; there are permits and zoning issues. I can put a couple hundred square feet of cells on my roof with no problems. Today's cells produce about 1kW per 100sf and the area would only decrease.

Plus I can't buy a residential wind turbine for $1/w. For a turbine (installed) in the 1-5kW range it costs about $3/w, with a big chunk of the cost being the tower & installation. $3/w is the same as the solar listed.

I haven't found a turbine for $2/watt until I hit the 20KW level. $40,000 is a lot to recoup and 20kW is a lot of residential power. I'll note that a 20KW turbine is only about about 2% more than 10kW turbine, so wind scales real well once you commit to spending $40,000+.

Which means that individuals will still find solar to be more appealing than wind because a) no tower, b) no moving parts, c) no moving parts located at the top of a 70' tower. Communities will likely find wind to be more appealing because a) it scales well, b) it requires fairly small land area, c) wind is generally more available, especially if you are willing to build a 100' tower.

So stop being a downer on solar, it's really like watching BSD & Linux fanatics going at it. If nothing else, the wind industry should be promoting solar to help get uniform nationwide grid-tie legislation passed.

No, dummy!

[Trails]

The solution is easy! We use cold fusion to buffer. Since there's no steam circuit to heat up, we can have it going very quickly.

And to those who complai about the weather, once we build the space elevator, we can put solar collector in orbit and beam power down to earth!

With all that power, we can finaly build robots to clean our homes, cook our food, even "companion" models!

Cold fusion, solar energy, space elevators, and robo wives! I think I just messed my mylar pants!

Solar is already cheaper in some areas

[NatteringNabob]

once you count the infrastructure costs. I own an off-grid second home which is about 3000ft from the nearest power pole. The cost to extend the power to our house is estimated by PG&E at about $20/ft, so about $60,000 to get to our house, and that is *after* you have negotiated an easement over the neighboring properties. By contrasts, a complete off-grid systems run about $10000/KW, so you can have a nice 3KW system for about $30K, or 1/2 the price, and the 'generation' cost after that is the cost of replacing the lead/acid batteries, which, unfortunately, are still the best storage alternative. Yes, it only works in places where there is a lot of sunlight, and you still need a generator for night and winter months, and it helps a lot to have all florescent lights (which, fortunately has also improved dramatically). The fact of the matter is that once everything is factored in, solar already looks pretty good. If you factor in the cost of things like conquering oil producing states (as well as the cost of maintaining a military large enough to do so at any time), solar is an absolute bargain.