Installed, $10/watt is an upper bounds on PV panels. Given that an average house needs 2kW after reducing consumption, it's nice that the government (one way or another) will give you almost half the money back (link to CA, U.S., and utility rebate programs?).

The cost a lot because they are made of expensive materials that are hard to come by. Also, demand keeps going up. Many companies are working on the problem, but prices seem to remain somewhat high. Higher-efficiency panels (40% was recently -- 2007? -- broken in the lab (current commercial panel efficiencies?) also command a premium.

Here are some prices people have noted:

• Soren saw panels from 2W ($25) to 100W (~$600) at Fry's electronics in 2006
• http://www.buildmartstore.com/solarmodules.html has 150W @ 24 VDC for $1200
• http://www.gaiam.com/retail/product/41-0216_MSTR has 9W for $99, 18W for $180
• http://www.gaiam.com/retail/product/17-0170 has 13W for $135
• Jonah has seen great deals on ebay for used solar panels. I spotted 30W for $60 yesterday.

PV Panel info

• company producing less-ugly panels(?)

Distribution of light/power

Stuart is collecting data about how much his new 5.1 kW setup is able to collect. Recently (May '07), it's been producing 35 kWh/day (roughly 7 optimal hours, but it starts and stops collecting during a 14 hour period during which it is producing 50W at either end). Neatly, his consumption is currently 35 kWh/day, so he is actually breaking even. We'll see whether he can switch to lower-powered servers (extra bonus because he air conditions that office) before the summer heat causes his air conditioners to spin up.