Free power! Yeah, that's the ticket.
Clean, free power from the sun!
Well, no, not quite.
First: clean. Manufacturing silicon from silicon dioxide (quartz) consumes about 12 megawatt hours per ton of raw silicon produced. Yeah, that's *mega*watt hours. Then, the raw silicon must be refined to get rid of impurities - an exotic chemical process followed in the end with an energy-intensive electrolytic process for recovering the metallic silicon. In all, about 200 megawatt hours is consumed in the production of a ton of silicon solar cells. That's a lot of power - power which must be generated somewhere.
Next: free. In the recent past, solar panels have sold for about $10/watt - that is, a panel with a rated capacity of 100 watts (in the tropics, at noon) would cost about $1000. That's hardly free power. If you work out the numbers, at our local power cost of $0.08/kwh, that 100 watt panel would be paid off in 85 years.
But something has been happening in the solar cell marketplace recently. Solar panels can now be found for under $2/watt (17 year payback), and the bare cells are available for amazingly low prices. And so just before Christmas, I bought a kilowatt's worth of solar cells and paid an amazing $350 for them - that's $0.35/watt - a payback period of only 3 years. Those are numbers I can live with!
|An early Christmas present!|
Now to actually construct the panels in a way that will last, the challenge will be to keep the cost from climbing back to that $2/watt for which commercial panels can be had.