Letter from John Grady, Slough Road, September 17, 2010

Anthony Marolda raises some good questions about redistribution of wealth in support of solar [Letters, Aug. 27]—should government take from 50 taxpayers and give it to the 51st for solar panels? But rather than get into that, or the true cost of oil, or politics, I contend that government support of solar is not at all well thought out regarding the physics of it. It is an extremely misguided engineering loser.

Stephen Mirarchi [Letters, Sept. 10] talks about solar parity with grid in five years at about 10 cents per kWH. However, that is at noon, which does little good when you need a light at night, or a refrigerator 24/7. It is a rule of thumb that installation, profit, inverters, etc. at least double the cost of solar panels as installed, so achieving “parity at noon” i.e., the peak output time, is not quite a game-ender. That parity is with the panel sitting on the ground connected to a meter. But only for a few hours a day.

The actual averaged output over 24 hours varies between about 12 and 16 percent of noon, averaged over a year, so you have a factor of 6 or 8 on top of the installation doubling, if you want your “rated”/needed output power 24/7. And that implies 100 percent efficient storage coming and going into something, an impossibility. Inverter and wiring loss factor is at least 1.3. So now our 10 cents noontime cost is approaching $1 for 24/7 availability. And that assumes there is a no-cost storage facility if you DO put on eight times as many panels to get what you need 24/7.

Today, the answer is, don’t worry about it—utilities are obligated to accept net metering so that what you don’t use when it’s generated you put back on the grid, and let the utilities figure out how to meet demand when the sun goes down (or the wind dies down).

Nice, that free storage and net metering is mandated by law (physics be damned). So what should we be asking taxpayer dollars to support, if we really want to reduce the carbon footprint of the grid? It probably includes the “n” word (nuclear), pumped hydro, and significant upgrading in long-distance transmission capacity.