Thursday, May 24, 2007

Whats wrong with Solar Power

All my life I've been an alternate energy enthusiast. As a teenager I built a 1Kw wind generator in my back yard. It exploded in a blizzard. (cool!) I've build solar heaters, solar cookers and small solar electric panels.

With all the recent articles about cheaper solar cells and such I went on-line and looked up what a home solar system actually costs. Turns out it's not the solar cells that are the big cost. It's the combined system.

Here is the math I did. Currently power is about 9 cents per kilowatt hour from the electric grid.

(Prices and systems from but this is not a cut against them. They just seem to have the best systems and prices.)

First a grid tie system. This is a bunch of solar panels, and a controller, mounts, disconnect and such. Ready-to-go. The system is $14000 but there are rebates so lets say $10000.
The solar cells are 2300 watts raw output. Given a 5 hours average power per day, 6 days a week, 52 weeks a year, it comes out to 3,500,000 watt hours per year. Divide the cost by 3.5 M and you get $2.78 per kilowatt-hour in one year. Of course the system last 20 years so divide by 20 and you get 13.9 cents per kilowatt-hour. Hmm, 1.5 times the cost of grid power.

If the system breaks earlier, or needs repair the cost goes up. One rock from a curious neighbor kid and the cost goes waaaaaay up. Also you can put the $10,000 in a CD and get about $200 per year. In 20 years this is $4,000. You could add this to the system cost so it is $14,000 instead of $10,000, raising the cost per kilowatt-hour, and you'd have the $10,000 left over at the end.

The solar panels are $610 each and there are 18 of them thus $10,980. The controller is $2,500. Since it is a package deal they cut the cost a bit.

Now lets assume the solar cells cut in half in price. The panel price will not cut in half since it includes glass, frames, and such. So we'll guess $3000 off the starting price, and after rebates you would save a bit less. So lets assume $2000 savings. Now the electricity over 20 years costs 11.1 cents per kilowatt-hour. Getting closer.

The same calcs on a battery off-grid system you could run your (very efficient) house on is 26 cents per kilowatt-hour because of all those batteries and power conversion. Here the solar cells base cost is $4880 or roughly half the system cost.

Oh, and don't even think that when you move and sell your house you will get any of the cost of the system back. It might even be viewed as a detraction from the value of the house. So you better live in the same house for 20 years.

The point I'm trying to make here is that the solar cell cost is half to one quarter of the system cost. The power controller and the batteries are most of the rest of the cost.

What will bring down the cost of home solar power will be when the systems get mass produced and the cost of the parts comes down.

The other issue with solar is the complete rejection of solar by utility companies via. regulatory obstruction. Don't think so? Try this article. Then there are the local regulations. The subdivision I live in has a flat out ban on any solar panels and wind generators. The home owners association is a bunch of 'tree huggers' yet ban anything actually ecological because it might not look 'just right'.

There is a bright side to this. These systems are not increasing in cost, while electricity is increasing in cost. If the states pass alternative power friendly laws in favor of solar installations, such as a law prohibiting home owners associations and towns from blocking installations, then solar could succeed.


Michael said...

This article ignores the likelyhood that energy prices will increase as we try to stop global warming and clean fuel becomes scarcer. Also the other elements in the solar power system will become cheaper as the economies of scale kick in, so it is not just the cells that will get cheaper.

I think the real question is: Is this the right time to buy a solar power system, and I suspect that it is not quite, since there are several technologies that will make it cheaper that are just becoming commercialized, like thin film panels and solar roofing tiles (which share the cost of covering the roof with your power generator), as well as new cells that are capable of using more wavelengths of light.
Another thing to keep in mind is that in remote areas where running powerlines is very expensive it is quite viable now.

In any case, a much better case for using solar power can be made using solar thermal energy to heat your hot water, especially in warmer climes, as it is much more efficient and a cheaper installation. My parents got a solar water heater in 1982, and it is still going strong, only needing minor repairs after 6 hurricanes since then.

Thunderfist said...

No it does not ignore the increase in energy costs in the future, it directly mentions that.

It also directly mentions the lowering of component costs as volumes increase.

You are correct that rural off grid power is currently very viable. In fact that is probably what will drive the volume up over time.

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