A new study commissioned by leading US solar groups has found that rooftop solar energy systems are the most efficient means of cutting electricity bills.
A white paper released by Westinghouse Solar, in association with the California Solar Energy Industries Association (CALSEIA), found that residential power use accounts for nearly one quarter of all power usage in the US, outstripping even the energy spent on driving cars, which uses around 17 percent of total energy.
The paper, entitled “Reducing Home Energy Costs by Combining Solar and Energy Efficiency,” examined 30 different test simulations to find the best combination of solar energy generating system and energy efficiency measures to reduce “payback” time on the cost imposed on the homeowner.
– Lighting retrofits are always cost effective (paybacks < 1 year).
– Weatherisation and insulation energy efficiency measures are most cost effective in old homes in cold climates (payback <3 years), but are not cost effective in newer homes or in temperate climates.
– Basic building shell and ventilation energy efficiency measures are most cost-effective in cold climates, but have long paybacks in more temperate zones (payback 20+years).
– Rooftop solar power systems have good paybacks regardless of home condition in sunny areas and in areas with either high electric rates or high solar incentives (payback 5-15 years).
– Solar hot water systems have good paybacks when the fuel source for hot water is electricity, or if there are local incentives in areas using natural gas with a tiered rate structure.
– Upgrades to Energy Star appliances and equipment are generally cost-effective when replacing broken or obsolete equipment, but are generally not cost effective when the existing equipment is still functional (analogous to not upgrading to a new, higher mileage car if the old one still works).
The white paper asserts that what it calls “the low hanging fruit” of household energy saving measures such as insulation and Five Star Energy rated appliances have largely been achieved in American homes.
“Generating the remaining energy required by the home will have the biggest impact on home energy consumption. Put simply, we cannot conserve our way to energy independence.”
Source (PDF)
