By G.E.T. Staff
We all know that solar photovoltaic (PV) cells work much better in Arizona than they do in New Hampshire or Vermont. Like many other things we have always known about, however, the real story is a bit more complicated than that.
One of the problems with PVs in the desert Southwest is that they overheat, and when they do, their efficiency goes down. How much it goes down depends on the specifics of the PV and the temperatures to which it is exposed. The important thing, however, is that many or most PVs work better in cold weather than in hot.
Another aspect of this problem is that while PVs degrade very, very slowly, they degrade at a speed that is somewhat related to the temperatures at which they have operated. Hotter temperatures produce more damage.
The result of this is that solar PVs make good sense in northern latitudes, even though there is less sunshine. The cloudiness of a New England afternoon may slow them down, but not necessarily as much as a hot afternoon in the desert.
As it happens, Nancy Rae Mallery, the publisher of Green Energy Times, has some experience with this, because she has lived for years in an off-grid house provided with 100% of its power by sunlight. Her 3.8kW solar system, a ground-mounted array, produces a good deal more energy than her household needs, and her batteries are just about always at full charge. That is true in the summer, when the days are long and warm. It is also true in the winter, when the days are short and cold. Asked how the two compare, she says, “I have never noticed much difference. The sun always shines before the batteries get too low and charges them back up. It is true that there are fewer hours of winter sunlight, but that doesn’t mean you can’t produce plenty of electricity. The generator has not needed to come on to help in over three years. It feels great to be energy-independent and not have to rely on fossil fuels for my electricity.”