Giving Up Alternating Current

An anonymous reader writes: Yesterday we discussed Soylent, the artificial food substitute created by Rob Rhinehart and his team. As it turns out, this isn't Rhinehart's only unusual sustainability project. In a new post, he explains how he gave up on alternating current — a tough proposition for anyone living in the U.S. and still interested in using all sorts of modern technology. Rhinehart says, "Most power in the US is generated by burning coal, immediately squandering 67% of its energy, then run through a steam turbine, losing another 50%, then sent across transmission lines, losing another 5%, then to charge a DC device like a cell phone another 50% is lost in conversion. This means for 100 watts of coal or oil burned my phone gets a mere 16."

The biggest hindrance was the kitchen. As you might expect for the creator of Soylent, he doesn't cook, and was able to get rid of almost all kitchen appliances because of that. He uses a butane stove for hot beverages. He powers a small computer off batteries, which get their energy from solar panels. For intensive tasks, he remotes to more powerful machines. He re-wired his apartment's LED lighting to run off direct current. Have any of you made similar changes? How much of an effect does this really have?

Comments

Outdoor

[Anonymous Coward]

It's the new outdoor trend anyway. All the lighting is obviously LED, so no problem there, the gadgets all transform their AC to DC anyway, so no problem there as well, you just need a decent lab trafo.

Washers and dryers that use solar heated water are no problem either, they mix warm and cold as they need it.
Even the small 12 Volt Camping washing machines work very well nowadays.

You cook by gas and use a gas refrigeration unit as well.

There's a German project the 'direct current house' (in German obviously)
http://www.dasgleichstromhaus....

They have solved many problems.

Re:Outdoor

[Technician]

Due to the very poor selection of DC appliances and often their RV bloated price tags, I have opted to keep AC, but generate it locally. Instead of buying a DC to DC supply for a laptop to get 19V for about $100, I bought a 1KW inverter instead for about the same price. If I don't want all my lights to be Fluorescent Cool White in color, I can use the 9W 3K bulbs instead in a warm white with high Color Rendering Index >94%. Try it. Try to find 12V RV bulbs that are not Amber, Red, or Cool White 6K. Most of the outlets in my RV are running off the inverter. Only the kitchen and bath loop are still on traditional shore power or generator along with the AC. This limits the generator runtime where shore power is not handy.

I have not trimmed my home use enough yet to cut loose from the grid. Heat pumps and long wet winters on solar just is not a match yet. They haven't fixed the solar when the sun doesn't shine problem yet.

I don't have to mess around with trying to adapt everything to 12 or 24V. With a good size deep cycle battery, even normal microwave oven, blow dryer, other short duration high amperage loads are possible that is simply not an option on DC.

Re:Outdoor

[Barsteward]

they still work but at a much reduced capacity so if you had double the panels you usually require, you should be ok-ish.

Re:Outdoor

[FlyHelicopters]

I can tell you are not from the Pacific NorthWest. One or two days in winter won't keep the battery charged.
Seattle has an average of 152 non rainy days per year. They claim 58 sunny days a year. Pacific Northwest is not a great place for solar.

A whole lot of people on this site aren't from the north in any respect... they clearly have a world view that doesn't know what 5 feet of snow looks like. Shame, because Boston and the North East got all that coverage recently for the massive snow storms, what good would solar have done in all that? Wind wouldn't work there either in those conditions.

This is why, at the end of the day, nuclear is what we really need.

But, sadly, the environmentalists are against that too.

Re:Outdoor

[bobbied]

they still work but at a much reduced capacity so if you had double the panels you usually require, you should be ok-ish.

Oh ye of great faith and frail engineering ability...

What are you going to do? Buy twice as many solar panels so you can charge your battery to hold you though the night? And as the original poster said, you planning to live without electricity for 6 days when the sun is behind the clouds for a week?

There are ways to make this work, but you have to understand that you will have to pay for capacity you don't usually need in both your batteries and solar panels and then still accept that there will be times you will run out of power. Plus you will REALLY drive up your cost per watt. I'm thinking you will likely pay about 4x what it costs for just a daytime system that carries your needs when the sun shines. You will need more than double the panels and add batteries to carry your load for a specific number of days.

If you want a week of "standby" for that rainy week, then you will need 7 days of battery capacity (ouch) plus enough additional collection capacity to charge these batteries. Say you want to recharge in 3 days, then you will need to have 2.5 times the panels it takes to carry your load for a day (plus the original panels that carry you a day). So for a system with 7 day backup and 3 day recovery, you will require 3.5 times the original collection capacity and enough batteries to hold 7 days of use.

Solar is not competitive economically when you are not talking about charging batteries. Going totally off grid requires significant investment in capacity BEYOND just your daily needs, unless you don't mind being in the dark pretty often and then the costs multiply, making an already bad ROI much worse.

AND I would like to mention that MOST batteries have losses when you charge and discharge them, some being as high as 30% losses... Just think about how many more solar panels you will need to buy for this scheme.... It's going to be nearly 4 or 5 times as many.... Good luck making that pay..

Re:Outdoor

[Jarik C-Bol]

I lived in a house that was totally off grid. It actually was never on grid, because the owners already had a wind turbine back in the day when the utility companies where doing the rural electrification project, and declined to be added to the grid. This house had coal heat, gas and wood stoves, gas refrigeration, and no AC at all. Located in central Montana, it was equipped with a bank of around 12 CAT bulldozer batteries, (which replaced about twenty 1 gallon square glass jars with lead plates) over 200 square feet of solar panels, a small wind turbine (about a 2 foot blade) and a backup propane generator, that was set up to automatically start up and top up the system if it dropped below a certain charge level. So basically, all the system had for load was incandessent bulbs, and occasionally a television. In the winter, that generator ran intermittently during the day, and after dark, it ran until you went to bed, and shut all the lights off. Obviously, using LED's and more power efficient TV's is possible now, but it takes a hell of a setup to go all off grid. (you could not run a modern computer or a microwave on that system, the computers where to sensitive to the square sin of the inverters, and would randomly restart. Microwaves would pop breakers if not plugged in directly to the generator.)

Re:Outdoor

[cptdondo]

As someone who works in the RV industry, you're right to some extent. But also, appliances in houses do not get shaken, bumped, subjected to temps from well below freezing to 120*F, so the testing and quality is far more stringent.

Lastly, we use a lot of appliances common to boats, and durability and repairability are also important. You can't go to Walmart when you're on a boat; you fix, patch, or do without.

Our customers who installed dorm fridges because RV fridges are too expensive have found that the dorm fridges don't last too long.

Re:Outdoor

[Lumpy]

I had a solar powered and wind powered home in the Michigan Upper peninsula. where we average 30 FEET of snow in the winter.

It is absolutely doable. You cant be a bran dead sloth like the typical american though. you have to do some maintenance. About 20 hours a years worth.

Its made from People!

[chriskovo]

Shouldn't it be powered by his sense of self importance? Or at least by PEOPLE!!

Nonsense

[Anonymous Coward]

He's still living on the electrical grid, he's just not using it at home.

Also, WTF? "I enjoy doing laundry about as much as doing dishes. I get my clothing custom made in China for prices you would not believe and have new ones regularly shipped to me."

Re: Nonsense

[Anonymous Coward]

Wow I didn't even make it that far. This guy is clearly an idiot. He didn't get rid of his dirty fuel burning ways, he just outsourced them to others. Ordering new clothes is way worse than washing some. And as far as this soylent stuff is concerned wasn't it proven that supplements aren't very good and you need actual food to be healthy? Absorption rates of supplements aren't good from what I read and they should be used to supplement an actual healthy diet.

Re: Nonsense

[Talderas]

And as far as this soylent stuff is concerned wasn't it proven that supplements aren't very good and you need actual food to be healthy? Absorption rates of supplements aren't good from what I read and they should be used to supplement an actual healthy diet.

Why do you think he's making such questionable choices regarding dirty fuel burning ways?

Re: Nonsense

[TWX]

The line losses are a NIMBY problem, people don't want power plants near their houses.

The fuel-source problem is people not being willing to pay for more expensive renewables, or in electing politicians that oppose them while continuing to subsidize fossil-fuels.

Those things can be fixed only if people as groups are willing to accept these differences and their costs, or if someone decides to put solar panels, at increasing personal expense given the utility companies' objections, on their property.

Re: Nonsense

[tlhIngan]

Wow I didn't even make it that far. This guy is clearly an idiot. He didn't get rid of his dirty fuel burning ways, he just outsourced them to others. Ordering new clothes is way worse than washing some. And as far as this soylent stuff is concerned wasn't it proven that supplements aren't very good and you need actual food to be healthy? Absorption rates of supplements aren't good from what I read and they should be used to supplement an actual healthy diet.

Exactly. He "cut his consumption" down by externalizing it all. Basically pushing it off somewhere else and hiding it.

That's like every other company out there - they pollute because the cost of pollution is basically free - the cost is externalized (well, it was until Obama introduced those regulations). When people complain about the "cost of complyihg" it means they're no longer externalizing the cost (free) and now having to pay for it.

Basically this idiot is making himself feel better by making society worse. He doesn't do laundry - but the charity he donates clothes is forced to do it. He's basically pushed the environmental impact, energy and cost of laundry onto some other 3rd party. Or if they deem it too dirty, they'll just toss it in the garbage. To him, he's "in the clear" still because he didn't throw it away directly.

Basically, the stuff this guy did was offload onto someone else - you can conceptualize this by asking - what happens if EVERYOHE did it? If it's truly for the environment, then if everyone did it, we'd be better off. If not, then no, it's not as good.

For an example - say check your tire pressure - most people will probably be on the slightly low side. But if everyone then pumped their tires to the right pressure, society benefits from the reduced fuel consumption, cleaner air (less fuel, less pollutants, etc). That's a real net plus.

Using less energy - that's a good thing too - or more renewables. But if you're claiming your coal-powered server in a datacenter isn't your concern if you remote into it, well...

What this guy did would be like RMS asking someone to open Microsoft Word for him because he needs to do something, while claiming to be only using free software. (Yes, I know RMS doesn't do this, but it's an example).

Plus, I'm sure he's got the income to support this kind of lifestyle - enough to make a point, but really, I think I'd give it to the climate change deniers. For they can poke enough holes in his "living arrangements" to basically say "if we agree to cut back, look at how we'll live - and look ,he's not even green if he needs all that stuff!".

I'd say he's among the worst kind of "environmentalist" around - a green-washer.

Re:Nonsense

[jandrese]

It's a real shame this guy hasn't found a generator that can run off of his sense of self satisfaction. It would end his energy problems forever.

Re: Nonsense

[Tailhook]

he just outsourced them to others

How is that different than what we're doing to ourselves as a matter of policy? Every time we tighten the screws on some industrial chemical or fossil fuel we simply chase another industry to Asia or damn up another Canadian river. He's just following this pattern on an individual level.

Re: Nonsense

[WolfWithoutAClause]

No, careful here. Outsourcing CAN actually improve the environmental aspects of what you do.

For example, centralised servers have far more chance of being run by renewables than your home computer. Google for example, is tending to do stuff like build their servers near hydroelectric plants or where there's wind farms or solar available.

So outsourcing your needs CAN actually be a good thing; and if everyone did it, it's a net positive.

He wasn't able to give it up.

[FictionPimp]

"For intensive tasks, he remotes to more powerful machines".

So he can't survive without it....

Re:He wasn't able to give it up.

[MikeDataLink]

Exactly my thought. That is cheating. That's like not owning a car, and then riding in taxis the exact amount you'd have driven.

Re:He wasn't able to give it up.

[ciaran2014]

If you had to remote to another machine for every intensive task, do you think you'd maintain the same volume of intensive tasks?

In summary, he reduced a bunch of things to zero, and another heap got reduced greatly, and then some smart aleck comes along and says he did nothing because this thing over here didn't get reduced much. Someone's missing the point.

Re:He wasn't able to give it up.

[khasim]

If you had to remote to another machine for every intensive task, do you think you'd maintain the same volume of intensive tasks?

Yes. AND EVEN MORE! I have machines dedicated to running a single task each and I remote to them.

If I had to run all of those tasks on one computer which was also my daily use computer I would run far fewer tasks.

Re:He wasn't able to give it up.

[AaronW]

HVAC uses 3-phase AC power which is actually pretty efficient for motors, especially if you want motors that are going to last a long time. Pretty much all brushless motors are driven by AC (even computer fans have a controller inside to generate AC). 3-phase is great for motors that run at a single RPM, such as what is used in compressors and pumps for HVAC.

Re:He wasn't able to give it up.

[bobbied]

AC by virtue of alternating, passes though zero current flow and zero voltage 120 times a second in this country. When you have an arc, you are passing an electric current though a plasma and that requires that you keep it hot and ionized. It is the current that keeps the plasma hot and ionized.

As a switch contact opens, initially the distance between the contacts is under the flash over voltage and an arc of plasma is formed. This arc requires current to keep flowing though it to be maintained and as the contacts separate further the resistance of the plasma path increases, lowering the current. Eventually in AC circuits, the voltage needed to maintain the plasma path starts to cycle under this minimum value for longer and longer times and current starts to fall off on average. This falling current, makes the arc plasma start to fade and will eventually extinguish the arc during the times when the current and voltage cross the zero level.

DC has no regular fall off in the plasma because it is always there, full on, full current. This means that switching similar voltages and currents in DC requires additional distance over AC. DC starts the arc and builds the plasma without stopping and only the resistance of the plasma as the distance increases is what will cause the current to get lower and lower until the arc extinguishes. There are no "off" times like there is in AC so the arc exists over a larger distance.

ALSO, on very high voltage AC circuits, it is possible to disconnect the circuit during a zero crossing. In that case, assuming you can get the contacts far enough apart to avoid flashing over, there never will be an arc to start with. Even though it's mechanically difficult to move things that fast, they sometimes do this kind of thing to suppress the arc in AC. This doesn't work in DC because there is never a zero crossing.

DC is more dangerous

[circletimessquare]

this experiment is fine if you're doing little LED lights and laptops, but if you're running something like air conditioning or a washing machine you're building a fire hazard and a mortality risk

the decision to use AC over DC was not random nor taken lightly, there are many factors involved (heck, it was a major engineering, corporate, and PR war between Edison and Westinghouse: https://en.wikipedia.org/wiki/... ), but the right decision was made

for our modern world where some people only care about their laptop and smartphone, it does indeed seem silly and wasteful to convert to AC then back to DC, especially if you've ever tried charging electronics in a car. but there are of course many other uses for electricity, and the navel gazing small electronics crowd is but a minor topic

but i do see a time in the future as more people use local solar and other renewables, that a small DC subsystem is made available in the house for electronics like computers

It's nice to have ideals

[gavron]

I respect the man for having ideals and trying to live up to them.

Of course he has fresh water. That comes from his pipes. Some requires transport from the Colorado River and that uses fuel. Some requires desalination from the Pacific Ocean and that uses fuel. With a water bill comes a related sewer bill. Sewer and effluent treatment require chemicals and fuel.

Of course he has batteries. That's how his solar cell provides his DC power. Both solar cells and batteries cost exotic chemicals/components, and take fuel to produce. Solar cells don't degrade as much over time but the typical deep-cycle battery requires replacement every 24-36 months [depending on the charge, cycle, use, etc.]. This also applies to the TMO cellphone battery he uses to power his TMO Internet.

Of course he buys his clothes from China - has them shipped - and throws away old clothes. This way instead of using water and detergent and some electricity (or some 25 coins and a laundramatt) he uses a lot of jet fuel, some delivery truck fuel, throws away cardboard boxes and plastic wrappers (think hydrocarbons which could be used as fuel, and fuel itself). He feels better because he donates his old clothes. I'm not sure that he thought about this much because ***ALL THE OLD CLOTHES HE DONATES ARE WASHED BY GOODWILL*** or whomever prior to putting on the shelf. So he costs the environment more, not less.

Lastly... that TMO Internet again... he is one of the people who encourages TMO to have towers. Towers have little generators on them so they don't lose power in storms, power outages, etc. Those use fuel which goes bad after a year and must be replaced. That means once a year cellphone tower generator fuel tanks are purged and dumped and new fuel is acquired and put in the tank. [Yes, some carriers have a 2yr schedule and some don't discuss their schedule, but if we're talking ideal... here you go.]

It's good to have ideals. It's nice try and live by them.

Ehud Gavron
Tucson, AZ, where 4 months out of the year the temperature is above 100F and the humidity above 40% so if you don't have an air-conditioner using direct-expansion gas (not a "swamp-cooler" or "mister") you will bake. They don't make any that run on DC. Even if they did, that would be a LOT of solar cells!

Re:It's nice to have ideals

[Holi]

The typical deep-cycle battery does NOT need to be retired in 24 to 26 months lead acid deep-cycle batteries are more like 4 to 8 years longer if you treat them well. If you want to double that spend a little more (ok a lot) and get surrette deep cycle batteries, typical lifespan range is 7 to 15 years.

Re:It's nice to have ideals

[Nemesisghost]

Yeah, and I love that he thinks eating paste or eating out is actually using less energy that simply cooking fresh food that's locally sourced. Heck, growing a garden is trivial, even in an apartment and would reduce your carbon footprint, save energy, and cost you much much less. And I'm sure there are storage methods that would allow you to get rid of both your fridge & your stove if you really wanted to. But this guy didn't want to do that. His lifestyle is not about saving anything, but showing how much better he is than the rest of us plebes.

Re:It's nice to have ideals

[TWX]

Tucson, AZ, where 4 months out of the year the temperature is above 100F and the humidity above 40% so if you don't have an air-conditioner using direct-expansion gas (not a "swamp-cooler" or "mister") you will bake. They don't make any that run on DC. Even if they did, that would be a LOT of solar cells!

Actually they do make one with an AC/DC dual voltage motor. Lennox sells one. It's ridiculously expensive without even including the panels, but it was an option that we looked into a couple of years ago when we had to relace a 2.5 ton unit that had failed. The replacement alternating current model has a 30A circuit breaker on a 240VAC circuit, so it can draw a max of 7200 Watts. This 8000W system would be enough to power that air conditioner and have some to spare.

I have enough roof space for probably 40,000W of panels. The thing causing me to hold back is the electric utility. I want grid-tie with intentional islanding and battery storage if the grid loses power, and I don't want to get hammered with utility company fees like they're trying to get out of us if we go that route. I'd also like to get reimbursed a fair rate for the power I'd supply back to the grid during peak usage, but they're not interested in doing that either. I'm hoping that Solar City wins their lawsuit against the utility so that I can feel comfortable proceeding at some point down the road with this.

Re:It's nice to have ideals

[Phs2501]

The AC in a prius runs directly off of the HV DC batter pack. Go find a junked prius and loot the AC if you need some DC powered cooling.

No, the Prius air conditioner compressor is AC. The Prius inverter electronics converts the HVDC to the correct AC frequency to run the motor. So you'd need both the compressor and inverter assembly, which also includes the inverters for the motor-generators that move the car. And a 200V DC power supply. And all the right computers to get the inverter assembly to do something useful.

You'd wind up with a whole bunch of a Prius just to get a silly air conditioner.

From Special Issue: Inside the Toyota Prius: Part 5 - Inverter/converter is Prius' power broker:

The Prius also uses an electric air-conditioning compressor motor so that cabin cooling is maintained even when running in electric mode only. A second dc/ac inverter, with circuits located on a second ICU controller circuit board ringed with TO-packaged IGBTs, is deployed to power the electric A/C compressor from the HV battery pack. The A/C inverter IGBT packages are bolted to one face of the substantial heat-sinking enclosure of the ICU.

Might as well be dead! No! More butter, more wine!

[jabberw0k]

No birthday cakes, no cherry pies, no fresh baked bread, no roast pork with caramelized potatoes, no steaks, no cauliflower broccoli cheese casserole, not even any homemade French onion soup? I shudder to think what Julia Child would say to that.

These changes...

[Pollux]

He doesn't cook, and was able to get rid of almost all kitchen appliances because of that. He uses a butane stove for hot beverages. He powers a small computer off batteries, which get their energy from solar panels. For intensive tasks, he remotes to more powerful machines. He re-wired his apartment's LED lighting to run off direct current. Have any of you made similar changes?

No. I have a wife.

Re:These changes...

[Nutria]

No. I have a wife.

Gah. That's *exactly* what I was thinking. Also that he has a very reduced chance of transmitting his DNA to the next generation...

Somewhere Thomas Edison is Tenting his Fingers and

[mykepredko]

saying "Excellent".

50% is lost in AC to DC conversion?

[vadim_t]

Sounds like he's badly confusing something. I think he's badly misunderstanding how a rectifier works. Some waste of course happens, but not nearly that much.

Re:50% is lost in AC to DC conversion?

[slowdeath]

No where near 50% is lost these days in modern AC/DC or DC/AC conversion devices.
Solar panel DC/AC inverters run at 95% to 98% conversion efficiency.
Likewise modern AC/DC converters can easily achieve 90 to 95% conversion efficiency.
Unless he uses very bulky low voltage, high current cables, he could easily be losing 3-5% of transmitted DC power in those.

He would be better off keeping his residence on AC and covering his roof with as many solar panels as he can fit.

Re:50% is lost in AC to DC conversion?

[stackOVFL]

Yeah, your right. The low efficiency of a DC power supply is in the 80% range. http://www.xppower.com/pdfs/TA...

Think about the children!

[Media Archivist]

He has decided upon a very specific, and limiting, style of living. Bravo. Now try applying his philosophy to a household with children. Or a household frequented by guests. Try this in less sunny locales.

I think it is admirable to try to be different, and to advocate alternative. I am completely turned off by his holier than thou attitude and his dismissiveness towards that which does not fit his chosen lifestyle.

Re:Somewhere Thomas Edison is Tenting his Fingers

[Fire_Wraith]

Meanwhile, Nikola Tesla is spinning in his grave (probably at about 120hz).

Hard to take serious.

[bobmajdakjr]

Most of his personal savings just offload the burden of destruction to someone else, like taking uber (fossil fuels) and donating dirty clothes (water use, and being a scumbag donating dirty things) such that I was not entirely sure this was not satire.

Re:Stone Age...

[drinkypoo]

the biggest issue was there was no electricity for the well pump and water had to be trucked in so we passed on the house.

You can get a solar well pump too, meaning DC and either 12 or 24V. But presumably, you'd have needed to expand the solar system for that purpose. It also works best when you have a water storage tank sufficiently elevated above the point of use to produce useful pressure, because then you can make hay (or pump water, anyway) while the sun shines, and you don't need a bunch of battery — or, potentially, any.

not practical

[Karmashock]

Getting rid of AC for off grid applications makes sense. I'm all for it and look forward to the new DC appliances we're seeing come on market.

however, this article is not going to have people following suit.

I'm not giving up my quality of life. I don't have to and I don't want to and its the 21st century so anyone that disagrees can eat a rail gun round to the face.

I do believe in sustainable living. However, more in the way of breaking free from crumbling infrustructure and gaining a certain amount of logistical indepedence.

I'm a big believer in the backyard green house. I think solar panels and wind mills are a good idea AT YOUR HOUSE. And I am looking forward to economical energy storage systems that work at a personal level.

Am I dumping my refrigerator and cooking food on a camping stove? No.

Really none of this sustainable stuff works in an urban environment. Its sort of odd that so many people that like the idea live in the one place where it isn't possible. Logistically you're going to be depending on a very energy and resource intensive infrastructure and there's just no way around that in a city. That "IS" the city. The city is all the things the sustainable people say they don't like. Live in the suburbs and you have a CHOICE. You have enough property that you can do something. Live rural and you can go completely off grid for everything... food, water, power, whatever... live like the Amish or something. Yabba dabba doo. But in a city you're on the grid. I don't care if you shut off the breakers in your apartment or drink your own pee. You're on the grid because everyone around you is on the grid and you depend on them whether you're drinking your own pee or not.

Here is my suggestion for the urbanites. Support nuclear power. Worship the fucking atom.

Why DC is a greater fire risk

[Anonymous Coward]

DC arcs are strongly self-sustaining once ignited, as there's nothing to halt the continuous generation of ions which provide an easy conductive path. In contrast, AC arcs tend to self-extinguish twice a cycle when the voltage drops to zero, and so the AC arc has to re-ignite each cycle once the voltage rises high enough. Even if it does manage to re-ignite, the arc is not usually conducting the full cycle.

This reduced arcing makes AC a significantly lower fire hazard than DC, and the same effect happens to make AC switch contacts last much longer since breaking a circuit rarely arcs for more than a half cycle so contacts don't usually heat up and little metal is carried away from their surfaces.

Re:Stone Age...

[mlts]

I've looked at an off grid cabin for weekend vacations. A few portable propane cylinders would cover the fridge (assuming a pound/liter of LP gas a day), and it would also cover a water heater.

Solar wouldn't be cheap, but for a few thousand, I could place a number of solar panels, have them feed in via 1-2 decent MPPT controllers into a set of AGM batteries (so watering the batteries isn't an issue), then have a decent PSW inverter coming off for use. Because lead-acid batteries destroy themselves if they go under 50% SoC, take the expected ampere-hours you plan to use, and double it, at the least. This would easily handle almost anything but heating/cooling and the well pump (which can use 1500-2000 watts each.)

The trick with the well pump and an off-grid cabin, would be to run a generator so the pump can move water into an above ground storage tank 250-2500 gallons, then from there, a much smaller pump that runs from 12 volts can pump water from the tank into the cabin.

Of course, come Texas summers, that is what a generator is for on a weekend basis. I can get 8-20 hours of use from three gallons of gasoline in a 3000 watt Yamaha inverter generator, and for a small cabin, a 10k BTU A/C is more than enough to cool it down, assuming some semblance of insulation [1]. As an added bonus, with a converter (rectifier), it is a way to help keep the batteries topped off if the panels can't keep up with use.

Disclaimer: This is a vacation cabin. For a real house, it would cost over $40,000 for a solar panel setup that can handle the amp draw of the well pump and the A/C.

Of course, there are other items like waste water (I like using a cassette toilet and having cartridges on hand, since those can be dumped down the commode safely and legally once back home, and gray water can be filtered and recycled in a settling tank so it doesn't destroy the ground around it.)

[1]: Ironic thing is that if solar panels are mounted with air space between them and the rest of the roof, they function as shade, doing a decent job at keeping the place cooler, even though the panels are likely at around 150 degrees (66 degrees C) on a hot day.

Not our problem

[daninaustin]

We will never run out of either coal or oil. The price will increase to the point where they are no longer economical but there will still be a lot of both in the ground.

DC conversion efficiency

[technical_maven]

The problem with Rob's assessment is that his efficiency numbers, expect for power transmission, are way off the mark. It is MUCH better than he purports! DC to AC conversion is roughly 90% or more efficient these days so you are not saving much by using DC at home rather than AC. It is simply not worth it to limit yourself so much by having only DC appliances.

Not NIMBY: other factors

[Roger W Moore]

The line losses are a NIMBY problem, people don't want power plants near their houses.

That's not really true. Coal-fired power plants need to be located near a large, reliable water source for cooling and the closer they are to their fuel source the less energy is used to transport the coal. They also have to be of a certain size in order to operate efficiently. Hence even if everyone was willing to tolerate a coal fired power station in their neighbourhood most locations would be unsuitable for their construction, rural communities would be too small to warrant a power station even if suitable and even then there would be an increase in the energy to ship the coal the larger distances required. This means that only small reductions in transmission losses would be possible and since this is already one of the most efficient steps in the power consumption process you'd lose a lot more than you would gain.

Anti-Tesla Rhetoric!

[s.petry]

I was waiting to read about how AC kills and see some good ole electric chair demonstrations.. *sigh*

Re:Anti-Tesla Rhetoric!

[lgw]

What I find most annoying about all this is less the could of smug, and more the fact that household electricity use is such a small slice of the pie of overall US energy use. From wind power to this DC nonsense, it's obsessing on feelgood measures of little importance to the big picture.

This biggest slice of the pie is industrial energy use where electricity isn't part of the picture: "Primary energy use" by heavy industry for blast furnaces and the like. Industrial electricity use is the next biggest slice, followed by IIRC industrial transportation.

Only 1/3rd the power needs for the roof?

[Firethorn]

I can't say much about your specific situation, but in general if you're far enough from the equator for snow, the ideal solar panel will have a fair bit of tilt to it. At which point you have some options for snow-clearing. One of the popular ones is to use a relatively small amount of electrical heating once the snow stops to make the panel 'too slick' for the snow, at which point it simply slides off. Then the panels make up that energy through the day. Keep in mind that they're considerably 'slicker' that way than an asphalt roof.

Also, if your roof is only worth 1/3rd your electrical use, that may be something that you want to examine, because you could save considerable money for cheaper than installing solar panels fixing whatever is taking so much.

I say this because I can satisfy my electrical needs using about 2/3rds of my south-facing roof, and I'm in Fairbanks, Alaska. Disclaimer: Annual average; I'd have to sell electricity in the summer and buy in the winter.