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New Record For Solar Cell Power Efficiency

Posted by kdawson on from the onward-to-50% dept.

mdsolar writes "Renewable Energy Access is reporting that a consortium led by researchers at the University of Delaware has achieved 42.8% efficiency with a silicon solar cell. The method uses lower concentration (factor of 20 magnification) than the previous record holder (40.7% efficiency) so that it may have a broader range of applications, since tolerances for pointing the device will be larger. They are now partnering with DuPont to build engineering and manufacturing prototypes. They expect to be in production in 2010. On a roof, such cells would require less than half the surface area to produce the same amount of power as today's standard solar panels, which have an efficiency of about 17%."

32 of 351 comments (clear)

  1. Smog by Rixel · · Score: 5, Funny

    Hopefully, Solar Cell efficiency will keep ahead of smog cover in major cities.

    --
    Never play chicken with a passive aggressive.
  2. Waiting by Cassius+Corodes · · Score: 5, Funny

    Im waiting for them to reach above 100% efficiency before I'll buy

    --
    Control is an illusion, order our comforting lie. From chaos, through chaos, into chaos we fly
  3. hmmm. by apodyopsis · · Score: 4, Informative

    I'm interested in solar power as a means of lowering the fossil dependency - but there are other, better means of doing so. The CE manufacturers need to meet them half way and mandate more efficient devices that consume less power and bring back the humble ON/OFF switch that actually did turn off the power. Is it that hard to walk to the TV? And, of course, wind and tidal need to be followed up.

    The main problem is the general public. Everybody wants wind power (but not in their back yard) you have to actually change the law and rubbish collection to get them to recycle, and everybody needs to buy the latest and most powerful gadget on the market.

    Making a more efficient solar cell is an excellent step, but I'd be more interested in a more *cheap* one so they can be taken up on a mass scale.

    1. Re:hmmm. by NeilTheStupidHead · · Score: 3, Interesting

      Everybody wants wind power (but not in their back yard) That's one thing that I've never understood. I used to live about an hour's drive from a wind turbine and drove by it several times a day. I could never wait to drive by because I loved the sight. My new home is very windy and could benefit greatly from wind power. I simply cannot fathom the resistance to wind turbines.

      One thing I have always wondered though: given the fairly large surface area of the turbine blades, would it be possible to add a photosensitive material and pull a bit of power from the sun too? Probably not terribly practical at the moment, but I seem to recall reading, probably on /., about a paint on solar panel.
      --
      Lose: misplace or fail || Loose: not bound together
    2. Re:hmmm. by hcdejong · · Score: 3, Informative

      My parents live in an area that has lots of wind turbines. A few years ago, many of these were small, high-rpm turbines that were clearly audible from hundreds of meters away. Sitting in the back yard, you always had this droning noise in the background, this could be very annoying.
      Things did get better when they started replacing the small turbines with fewer, much larger ones. The turbines closest to their house were removed, and the new turbines ran at much lower rpm which means they produce less noise.

      As for sticking solar panels onto the turbine blades: this would make the blades heavier and less efficient. Also, you'd have to add slip rings on the root of each blade, and on the main shaft to transfer the power.
      Slip rings are expensive, heavy and they need maintenance, especially when you're transferring significant amounts of power through them.

    3. Re:hmmm. by JaredOfEuropa · · Score: 4, Insightful

      There is also the huge number of people who believe that the consensus of thousands of scientists on climate change is a "global conspiracy" and their fear that it may eventually mean, shock horror, more taxes.
      This believe is partly justified. The conspiracy isn't by the scientists, and isn't a global conspiracy either, but the climate scare has given the meddlers of any political stripe the perfect pretext to push their own agendas. The climate debate has been thoroughly politicised, at the expense of proper science. That does not mean that all conclusions are incorrect or made up, but very often peer reviews are sorely lacking, and many reports have had chapters and sections stricken in the final draft, because those sections could cast doubt on the severity or existence of human impact on the climate. In many cases scientists voicing such doubts have not been gainsaid, but fired from "scientific" institutions. Because a widespread doubt in our impact on the climate would spoil the party for the meddlesome politicians. The political stakes are huge, perhaps the largest of any issue in our history.

      Why are long term trends not taken into account in these reports, for example. It is rubbish to say that we cannot accurately predict climate that far into the future because our short-term predictions are not very good. After all, we cannot predict the little ups & downs in next month's weather, but we can predict that winter will follow summer and autumn, and we know what the trends are in each of those seasons. The long-term trends in global weather can be predicted as well.

      On a geological timescale, we are in high summer. Winter is coming, and in 10.000 years we'll be in an ice age. The start of the downward trend in average temperatures is imminent (which means anywhere between now and 1.000 years)... Perhaps that is why the IPCC report does not look any further than the year 2100, the scary hockeystick curve will flatten out after that year, and if you look even further it will drop. Our distant descendants (if any) may even be grateful for the extra CO2 we have released, since it might make the next ice age a little less severe.

      But with all that said, conservation and reducing our dependancy on a limited resource is a good thing. But I refuse to join in the mindless panic.
      --
      If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
    4. Re:hmmm. by pjabardo · · Score: 5, Interesting

      These are *VERY* wise words!

      Instead of making more money, people could work less. Instead of buying all sorts of shit, people could do much cleaner things such as talking, writing, riding a bike, going to a brothel, taking a walk, singing, playing a part on a play, painting, fighting (if not pushed too far it is not necessarily bad for some people...).

      It is way too simplistic to say that there is a law of nature that says we will end up using every resource available. We are supposed to be rational beings even if we often do stupid things. One of the things of being rational (or partly rational) is that we can choose what we do. We don't simply answer any call of the wild (even if there is such a thing).

      We are changing from a production society to a consumer one. We are becoming a bunch of morons that just sit and receive stuff. Not very different from the Eloi in H. G. Wells' The Time Machine. I don't think just consuming is satisfying enough. It is much easier (and faster) just to watch a movie than it is to tell a story and we end up watching 10 movies. Maybe a little boredom is good for creativity. It certainly is much cleaner than riding a car 100 km to do anything "new".

    5. Re:hmmm. by OldBus · · Score: 3, Funny

      I simply cannot fathom the resistance to wind turbines
      It's probably drag and friction...
    6. Re:hmmm. by Sandbags · · Score: 3, Interesting

      We don't even need a true power on off switch that has to be flipped manually. What we need is a remote power switch that cuts main power, and a small, rechargeable battery cell that can respond to the remote and re-activate main power. A tiny battery and a capacitor to have enough juice to throw a 2.5 volt magnetic switch would add about $1 in manufacturing costs to home theater devices, but save dozens per year in electric fees per home for "trickle" devices. All network devices should support Wake on LAN, but unfortunately, most don't (or do, but people don't know what that means or how to use it).

      Unfortunately, a lot of devices are always on, like DVRs, game stations with online access, and more. They do a lot of work at night updating databases, downloading new content, etc, and simply have to remain on. The fact that an XBox 360 doesn't spin down the graphic system power and down clock it's CPUs is a design issue we can change. An Apple TV box uses less than 20 watts when "asleep" and that included downloading content over wireless. Why can't the XBox and PS3 do that? They could even drop into an even lower power state when idle, spin down the HDD, and only "wake up" every 90 minutes or so to check for content without spinning the drive up again unless it needs to.

      Unfortunately, there are even more devices we can't really do anything about that are the real sappers in the house. The cable modem, wireless router/firewall, VoIP modem, second access point to cover downstairs, possibly an extra switch to add more than 4 wired devices (I have 7), and base station and answering machine for wireless phones. That's just the network. Now add the garage door opener, automatic sprinkler system, home alarm and smoke detectors (most run on house power and rechargeable batteries now), safety lights in your halls and bathrooms (night lights), and several clocks.

      I work for a computer systems manufacturer. We've got a meter (magnetic ring type thing) at the office that encircles a power line and displays the power being used by the device. We have it so we can document in our white papers the power consumption of our devices. I brought it home and played with it a few months ago when having a forum argument with another individual on this. My 27" tube TV used about 2 watts when sleeping. My 37" LCD used less than 1. My PS2 used no power (but the transformer was using 2 watts). My cable box used 12 watts when asleep, DVR used between 20 and 50 depending on what it was doing when asleep. What surprised me was the coffee pot was using 3 watts when off (it has a tiny built in clock). The 2 alarm clocks we have each use 5 watts. Adding up all my idle devices I was just over 220Watts in use! 10% of that was in scent plug-ins around the house and night lights, about 20% was in our cable boxes alone. 25% was in devices I can't turn off, like the garage opener, stove clock, built in microwave, etc. Another 20% was in my home theater equipment (amp, dvd, vcr, and TVs). There were some other random devices around as well, not including my network setup...

      After finding this out, I installed a "step on" power extension (like people use under the Christmas tree) in line between the wall and home theater, so I can press one switch at night to turn off all the device in the HT setup (except the DVR which has to stay pugged in all the time per the cable company or they'll void the warranty on the device). I threw out all the scent plug-ins in favor of passively diffused oils and popuri. I changed the few night lights we had out for LCD versions. I now have a programmable timer power strip in the computer room that I have 2 laptops, a small TV, a printer and a network switch hooked up to. Each night at 11:00PM the adapter cuts power to the laptops (which hibernate automatically after 15 minutes when on battery), my printers, the switch they're connected to, and the TV and cable box in there. My HTPC now uses sleep mode with Wake on Lan to save power and automatically shuts down and powers

      --
      There is no contest in life for which the unprepared have the advantage.
    7. Re:hmmm. by Ambitwistor · · Score: 3, Interesting

      That does not mean that all conclusions are incorrect or made up, but very often peer reviews are sorely lacking, The actual scientific literature published in journals is peer reviewed.

      and many reports have had chapters and sections stricken in the final draft, because those sections could cast doubt on the severity or existence of human impact on the climate. In many cases scientists voicing such doubts have not been gainsaid, but fired from "scientific" institutions. Please, give examples.

      And while you've raised the issue, shall we discuss political meddling in the opposite direction (cough EPA report cough)?

      Why are long term trends not taken into account in these reports, for example. They look at century time scales, but not longer, because (despite what you say) predictions are very hard to do for longer timescales, especially given the uncertainty in what humans will be doing in terms of atmospheric emissions and land use changes. Remember, climate physics is not the only input into climate prediction; you need projections of human activity as well. (See here.)

      Winter is coming, and in 10.000 years we'll be in an ice age. The start of the downward trend in average temperatures is imminent (which means anywhere between now and 1.000 years)... It is far from established when the next ice age cycle is going to start, and there are some who claim that due to patterns in orbital dynamics, the current interglacial could be exceptionally long (as long as 50,000 years). (See here.)

      Perhaps that is why the IPCC report does not look any further than the year 2100 Perhaps it is, as I said, hard to project much more than a century or two in advance.

      the scary hockeystick curve will flatten out after that year, and if you look even further it will drop The current rate of warming far exceeds the natural rate of cooling during glaciation. That rate of warming will eventually level off, but it's not going to be outweighed by glaciation any time in the next few centuries.

      It is true that eventually we will enter a new ice age, regardless of global warming, but no one is "ignoring" this fact. It's just farther off into the future; right now, the warming is what we have to deal with. If warming is a problem, you can't just ignore it because someday it will be cooler.

      Our distant descendants (if any) may even be grateful for the extra CO2 we have released, since it might make the next ice age a little less severe. If that turns out to be the case, it's better to release the CO2 then, rather than now, when we don't need it. As we have seen already, it's far easier to raise the temperature quickly than it is to cool it, having to do with the ease in emitting CO2 as a byproduct of civilization and with the long residence time of CO2 in the atmosphere.
  4. Solar cell? Pfftt..... by ihaveamo · · Score: 4, Funny

    I'm working on a lunar cell at the moment... the other 50% of a day is totally untapped!!

  5. How much power? by DoofusOfDeath · · Score: 3, Interesting

    On a roof, such cells would require less than half the surface area to produce the same amount of power as today's standard solar panels, which have an efficiency of about 17%."

    OK, but how much of a typical house's power would that supply? (I realize this depends on location and time of year.)

    Or how many panels would it take to give you a daily, full recharge of a plug-in hybrid in, say, Los Angeles? (Imagine that that would do for LA's smog.)

    1. Re:How much power? by Calinous · · Score: 3, Informative

      Peak solar power is around 750W per square meter of installation. With those new panels, you could get - let's say - 1000W per 4 square meters (40 square feet).
            Assuming you are going at work using 10kW (14 HP) average for two hours (both ways), and assuming 6 hours a day peak power, and your losses are zero, you need less than 15 square meters (160 square feet).
            Now, if you add 50% losses in the recharge system (car and house), you need to double that - 30 square meters, or some 300+ square feet of solar installation, inclined to an angle equal to your location's latitude (equator- flat roof top, Alaska - sharp roof)

  6. Re:feasible by Calinous · · Score: 4, Informative

    The most efficient use of solar power is the water heating system. Solar panels are a distant second for now - as they are very costly for the power they can produce (we assume your house needs heating or hot water). Depending on conditions, wind power might be a cheaper overall choice than solar panels.
            But in places like California, solar panels indeed pay for themselves

  7. someone convince my local government by Shivetya · · Score: 5, Interesting

    that renewable sources of energy are a good thing.

    why?

    because my HOA (home owners association) does not permit them. As such it would take State or local laws to override the HOA; because in many States the HOA rules have strong legal backing at the State level.

    This is akin to the problems satellite TV faced in many locales. There were numerous ordinaces, both at the HOA and local level which blocked satellite dishes. Even the small ones we are accustomed to today were blocked. It took a Federal Law to end that restriction. Unfortunately its going to take another such law to allow many of us to use renewable energy. Hell, I cannot even get rain barrels approved even though they would not be visible from the street.

    --
    * Winners compare their achievements to their goals, losers compare theirs to that of others.
  8. Efficiency is less important... by Anonymous Coward · · Score: 5, Insightful

    ...than price per watt. We got plenty of space we can cover with solar cells so it's not important that they are extremely efficient, just cheap enough so it doesn't cost much to cover large areas.

  9. Another kind of efficiency by fringd · · Score: 3, Interesting

    The real problem with solar power is not getting more watts per square inch; it's getting more watts per dollar. From what I hear, high grade silicon is prohibitively expensive. It takes more than 3 years to pay back your monetary investment. This information is probably based upon old panels though.

    These new panels may produce twice the energy, but is there any chance that they cost less than twice the dollars? What is the limiting factor in solar panel costs?

    I've heard that some people are working on polymer solar panels, this would seem to deal with the dependence on expensive silicon...

    1. Re:Another kind of efficiency by dwandy · · Score: 4, Insightful

      It takes more than 3 years to pay back your monetary investment.
      "Three years" should not be a 'too long' perdiod to re-coup your investment.
      • That's less than 4% of an average lifetime.
      • I'd take an investment that was guaranteed to pay back 100% every three years.

      I don't see energy getting any cheaper on this planet, and I don't see energy consumption decreasing.

      The problem is it's not just the solar panels: it's the batteries and other infrastructure (and then maintenance!), and the last time I looked at it, it was closer to 20-yrs to pay back a whole system, and the system had a 20-yr life expectancy. That's break-even assuming it makes it to life expectancy.

      What I am interested in is directly attaching an AC unit to a solar panel. Where I live it's generally only hot when it's sunny, so the AC would run for free.
      Since the AC is one of the most expensive things to run it's win-win-win-win:

      • I can run it guilt-free
      • It runs whenever it's hot
      • I don't need the other infrastructure
      • I will still pay for the panel in a relatively short time.
      --
      If you think imaginary property and real property are the same, when does your house become public domain?
  10. Re:What a pointless comparison by Calinous · · Score: 4, Informative

    Assuming your car has 20 square meters of surface, all of it oriented towards the sun. In Ecuador. With 100% efficient solar panels.
          You can get at most 20 HP of power from that. In your real situation, with maybe 5 square meters of surface available in the morning, and lower solar power, and the 40% efficiency solar cells, you get 2HP (or 1.5KW). Does it help? A bit, yes. If your car can load itself all day with energy, and know when she will reach destination, she could bleed the electricity storage battery (and reload it later). This way, you could get 10 square meters of max power, 8 hours a day, and with perfect efficiency in rest (charge, discharge, motor) you get 80 HP hours - or two hours at 40HP. Good enough for a commute... but...
          Now, you could buy solar panels at $5000 per kW (and 20 pounds). Assuming double efficiency is treble the price - you need $15,000 per square meter, so you'll pay $150,000 for solar on your car. Is it worth to drop your fuel consumption 50%? Or completely?

  11. About payback times by Anonymous Coward · · Score: 3, Informative

    It probably takes a lot more than three years to pay back the investment. A three year payback would be astounding. If that were the case, you could shut down all the existing power plants and run the country just on solar. OK, that's a bit exagerated because solar doesn't make power all the time. Even so, a three year payback would see a dramatic increase in solar use.

    The calculation that produces a three year period says that you start saving money after three years. It assumes that you borrow money to buy the panels. After three years, the money you save on electricity is greater than the loan payments. The link below has a graph. You will notice that the savings take a big jump after twenty years. That's when the loan is paid back and you aren't making payments any more. So, using the link's assumptions, the payback on the investment is about twenty years.

    http://www.ongrid.net/PVPayback.html

    The point of the link is that, even if it takes a long time to pay for the system, you can still save money by going solar.

  12. Re:feasible by knarf · · Score: 4, Informative

    That is why the two should be combined... Water-cooled Photovoltaic panels give the best of both worlds: cooler PV panels which are more effective PLUS warm/hot water for heating, hot water or - indirectly - cooling. The technology is out there. It is simple. It works. As to why is is not used that much yet? Good question.

    A search on 'water cooled pv' gives some interesting documents about experiments done with this combination. Read them and then go and build something like that. My 2 puny 11 watt panels are somewhat to small for this application but anyone who has (plans for) panels on the roof AND a need of warm water does him/herself a disservice by not looking in to this IMnsHO...

    --
    --frank[at]unternet.org
  13. Spot on. by ushering05401 · · Score: 3, Informative

    "The CE manufacturers need to meet them half way and mandate more efficient devices that consume less power and bring back the humble ON/OFF switch that actually did turn off the power."

    I recently had a new lady move in with me... and she insisted on actually unplugging things like my stereo when we were not using it. I was skeptical about the benefits of this tactic to save electricity, but being a curious person I was willing to humor her.

    By unplugging all of my electronic devices (there are many of them) when not in use we saved around $30 U.S. a month. Where was all that energy going? Not sure.

    If you are the type of person that has electronics in every room give it a try for yourself. Even if you don't care about being 'green' you will likely see a difference in your energy bill. Either way you win.

    Regards.

    1. Re:Spot on. by JaredOfEuropa · · Score: 4, Informative

      By unplugging all of my electronic devices (there are many of them) when not in use we saved around $30 U.S. a month. Where was all that energy going? Not sure.
      It goes to heat production, mostly. However I prefer a step forward rather than taking a step back by having to turn everything off. It is possible to make equipment have a minimal power consumption on standby, by only running a small circuit that looks for the "On" button being pressed on the device. A lot depend on how you power this circuit... a transformer is a notoriously bad way of doing it.
      Some equipment behaves nicely on standby. Use a Wattmeter to check how much your stuff actually consumes in standby mode; you'd be surprised how little some things consume when idle, and there is little use in unplugging these completely. You might also be surprised at the large amount of power drawn by plug in transformers (The "wall warts"). Removing these when you are not using them saves a lot.

      Another good way to save without sacrificing convenience, is to use a "master-slave" power block with your computer. I have a lot of inefficient transformer power supplies next to the computer, for printers, routers, LCDs, speakers, etc. I installed a "master-slave" system, that will automatically switch off all this rubbish when the computer is switched off. The power draw of this system when idle is minimal compared to those transformers, and you don't have to switch off every individual piece of equipment either,
      --
      If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
  14. fail by jovius · · Score: 4, Funny

    Yes, this is great, but solar power will eventually fail completely, and there are no guarantees for long-term investments beyond five billion years from now.

  15. Economically feasible? by Anonymous Coward · · Score: 3, Interesting

    What matters to me: Do those new cells finally "produce" more energy during their life than they required during manufactoring?

  16. Comment removed by account_deleted · · Score: 4, Informative

    Comment removed based on user account deletion

  17. Concentration Is Good by Doc+Ruby · · Score: 3, Insightful

    Concentration of a larger solar input area onto a smaller solar cell is nearly always better than straight 1:1 reception. The efficiency goes up with these materials, which of course is good.

    But also the concentrators are a lot cheaper than the cells. The concentrator is usually a cheap (compared to the cell) lens or mirror. So a 20x concentrator gets 20x the input energy, but for a much lower cost than 20 cells. And that cell is operating at higher efficiency, on 20x the input. So a $10 cell fed by 20 $5 concentrators costs only $110 instead of $200. 5% more efficiency in the cell is applied to all 20 concentrators, not just the 1 cell, for 200% efficiency. So it's double the efficiency at 55% the price, or over 3.6x the $:energy efficiency. In reality, the concentrators are better than 5x cheaper, and the efficiency gains can go higher than 5% greater.

    And then there's all the savings from cheaper replacement concentrators, which could even last longer than the cells (though the cells typically last >30 years), and dropping all the other HW from the 19 (or however many) extra cells in favor of "dumb" concentrators. In fact, since concentrators are so cheap, the cells might not require HW to track the Sun for maximum absorbtion, but just array the concentrators in an arc (or bubble) that always leaves an array of concentrators facing the Sun (and the rest off-axis), without consuming energy to move. Or extra parts, or computing, and saving all the maintenance costs, too.

    So the more concentration, the better. After all, that's how the engineers thought up this stuff.

    --

    --
    make install -not war

  18. Not too bad by Gr8Apes · · Score: 5, Informative

    I looked into this recently. Installing a ground based heat pump instead of a regular air conditioner would have been around $6K (instead of $2K for the AC). Note that this was for an old style 12 SEER AC unit that's no longer available against a 25+ SEER heat pump (get added bonus of generating heat). AC units have almost doubled in cost, and now are about $4500 installed (new US regulations require higher SEER units).

    Why didn't I get the ground based system? Because when it's over 100 F and your main AC unit dies, I couldn't wait for the ground based unit installation taking over a week. I will plan for one at my next house though.

    --
    The cesspool just got a check and balance.
  19. Re:What a pointless comparison by Rocketship+Underpant · · Score: 3, Insightful

    "Now, you could buy solar panels at $5000 per kW (and 20 pounds). Assuming double efficiency is treble the price - you need $15,000 per square meter, so you'll pay $150,000 for solar on your car. Is it worth to drop your fuel consumption 50%? Or completely?"

    This is the point where the central market planners jump in and shout that we should subsidize solar panels. But why does that solar panel cost $15,000 per square metre? Because of all the resources, energy, and labour consumed in producing it. Chances are those more than offset the gas you're not burning.

    When the manufacturer can make panels efficiently enough to be more affordable than gasoline, it'll be because they're finally less wasteful and polluting overall.

    A similar principle holds with recycling, by the way. In the instances where recycling actually saves on energy and raw materials, there is a cost savings as well, and the recycler will pay *you* for your bottles and cans. If the government has to make you do it, it's because the process is not cost-effective overall, and more waste is taking place in the recycling process than the recycling itself saves.

    --
    He who lights his taper at mine, receives light without darkening me.
  20. Being done in New Mexico by mdsolar · · Score: 3, Interesting

    I razzed New Mexico Governor Bill Richardson on my blog yesterday saying he is trying to keep the southerneastern US off solar so he can build a huge New Mexican Solar Power Monopoly to supply them: http://mdsolar.blogspot.com/2007/07/new-mexicans-c onspire.html(tinfoil hat warning). One of the projects linked there aims to do just this, havesting the heat generated at the panels for building heating. Engulf and Devour, that's his motto.
    --
    Register your home for solar power; fixed competitive rates for up to 25 years: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html

  21. Put some things into perspective by ilovethesun · · Score: 5, Informative

    Hi,

    I will try to put a summary to the interested folks around:

    A photovoltaic system is composed today by:
    - Module
    - Inverter DC/AC
    - Mounting system
    - Cabling
    - Measuring/Protection electrical stuff

    Most of the cost today is the module. Systems go (net) for 4-5$/Watt.
    More efficient cells (and modules) mean less installation costs. For the future, it will be important since cell and module prices will go down.

    Today, in California, if you take a system lifetime of 25 years, the kWh equivalent "price" is about 25-30cent.

    System price decrease is expected to be 5-10% yearly for the next 5-10 years at least. This means that very soon the PV power will be cheaper than the one sold by the utility.

    PV systems are perfect for distributed energy: a centralized power plant is not really cheaper or more efficient than a 5kW roof installation. And the energy transport kills the small margin that you had in favour of the big thing. That is why most utilities are not hot about PV: it is against their business model.

    For the moment, it is not cheap to get "disconnected" from the grid. Therefore, a mix of PV and other electricity is necessary. PV has a nice peak at max. consumption peak. However, the evening consumption must be covered otherwise. Wind, biomass, ocean waves, geothermal, whatever.

    PV in order to charge e-cars is OK today already. A car that uses 10 liter to do 100km, at a 20kW mean power, is using 20kWh energy for 10 liter gas, at 1$/liter it would be 50 cent/kWh. Make the calculation with your local gas price/gallon and you see that, even today, it is competitive. And cleaner. Only e-cars are not yet developed/deployed as they need to be.

    About Solar-thermal energy for cold- it works for mid-big sized equipments, it is cheaper and especially more reliable than electricity... PV supporting electrical AC is still a bit more expensive but both run a nice race.

    Ah, the typical guy asks about energy payback times: depending on technology, after 1-4 years your system has produced the energy needed to make it. Longer times belong to PV prehistory and to right-wing-thinktank analysis.

    Cheers!

  22. Re:feasible by xappax · · Score: 3, Insightful

    You deliberately buy things that aren't as cost-effective as other stuff, but that reduces CO2-emissions. Unfortunately your money aren't "lost", someone will get rich, such as the bank, or the company CEO, so even this method isn't 100% convincing to me.

    Seems like if you deliberately spend money on things that are less polluting than the mainstream offerings, you're helping to make that industry more economically viable. For example: if you buy residential wind turbines, the company that makes them will profit. Yes, some of that money will probably be spent on things that cause pollution, like employee salaries or airline tickets, however it will also be spent on improving and marketing a product that can reduce pollution dramatically.

    No institution or individual can ever have zero negative impact on the environment, but they can have a greater positive impact, so that their damage is offset overall. The question becomes, is a supposedly "green" institution really helping the environment more than they're hurting it? Some companies really are, and it's great to give them business, but some are just using environmental concerns as a marketing niche, and giving them money will do nothing but enrich them, and possibly allow them to create more pollution.

    I agree with your general sentiment, though. The key is being critical and informed about where your money goes. When you spend money, it doesn't just disappear - it goes on to pay for things that may be destructive or immoral, and couldn't happen without your money. Or, it may go on to pay for things that are constructive and really awesome. Though the amount of money you spend may be similar, the difference between these transactions is vast when you consider the consequences.