Lessons from the Electrical Frontier

More and more households are opting for photovoltaic (PV) electricity supply systems, and with them a change in household technology and lifestyle. In fact, a recent study estimates that at least 25,000 homes operate off the grid, relying on PV to harvest electricity and on batteries to store it. However, PV supply systems are quite expensive. Off-the-grid households effectively pay 25-75cents per kWh for their electricity. In the context of such high rates--almost ten times the on-grid rates--the frontiers of energy-efficiency are tested. There's a lot that those who are connected to the utility grid can learn from those living off of it. Thus, an article in this issue describes how one household in Arizona adapted to a photovoltaic (PV) electric supply system.

PV-powered homes require changes in technologies and appliances. For instance, one of the most efficient refrigerators manufactured today was originally designed to operate with PV systems. This is because the costs of additional solar collectors and batteries needed to supply precious kilowatt-hours far exceeds the costs associated with standard energy-efficient refrigerators. Similarly, fluorescent lights are the rule rather than the exception in PV homes. The costs of switching to compact fluorescents from incandescents are tiny compared to the savings from utilizing smaller solar panels and batteries.

The discipline imposed by a limited supply of electricity has forced many residents of PV-powered homes to attack insidious miscellaneous uses of electricity: the instant-on feature in a television, LED clock displays, and appliance power supplies that consume electricity even when the appliance is not used. Each of these draws only a few watts but, together, they can drain a battery without the occupants' knowledge. Even in this ultra-efficient home these energy culprits drew a constant 27W. The craziest example was discovered by the Arizona study--the electric ignitor in the gas oven. This particular ignitor is so inefficient that the gas oven probably consumes more electricity to cook a small potato than a microwave oven!

Normal utility-powered homes have their own, larger miscellaneous uses like sump pumps, water beds, and automatic ice makers. These can add hundreds of watts. Not surprisingly, you won't find these energy guzzlers in PV homes.

It's unlikely that electricity prices will soon climb to PV prices. Still, the measures and vigilance that residents of PV-powered homes take demonstrate that we can maintain our familiar lifestyle on just a few kilowatt-hours per day.

• Alan Meier