By Jon Fisher, The Nature Conservancy
We all want to decrease our energy use, both for the sake of our wallets and the benefit of the planet. But is putting solar panels on our home rooftops the best way to do that?
Residential solar systems (especially photovoltaic or “PV” systems) are substantially less efficient than their commercial counterparts. One estimate (admittedly controversial) from UC Berkeley professor Severin Borenstein says that residential PV systems cost roughly twice as much as their commercial counterparts (40 cents/kWh vs 20 cents/kWh)1.
Commercial systems have many advantages over residential: they are typically developed in locations with lots of sun, they can take advantage of innovative technologies that don’t work at small scales, they can utilize larger storage cells, and many other reasons.
Which brings us back to the question of why so many people love the idea of putting solar panels on their roofs. In talking to friends and co-workers who have solar panels, there seem to be two common reasons: the appeal of being energy independent and an “every little bit counts” desire to do their part to help. Installing solar panels on your own home is a more readily achievable goal than successfully lobbying to change the way we subsidize different kinds of power plants.
The good news is that there’s an often overlooked form of residential solar power that is almost always far more efficient than photovoltaics. Solar Water Heating Systems (SWHS) are typically much cheaper than PV systems, and focus on using heat from the sun to produce hot water (which is much simpler than converting sunlight to electricity).
While PV systems may take decades to pay for themselves (although this varies considerably state by state due to considerable variation in both subsidies and how much sun is available), solar water heaters can pay for themselves much more quickly. There is an excellent article on payback times in Home Power magazine (note that it doesn’t include subsidies, which vary substantially by state and city).