Sacramento – A new report commissioned by the California Solar Energy Industries Association says investing in residential solar will pay back faster than other forms of home improvement investments such as window replacement. With rising energy costs a home can benefit faster by installing solar.
Typical U.S. homes will cut their energy bills the most by generating their own power, rather than implementing energy efficiency measures. The news report, entitled “Reducing Home Energy Costs by Combining Solar and Energy Efficiency,” was written with the support of the California Solar Energy Industries Association.
The report, released recently in Sacramento, California, used Department of Energy software to evaluate three different ages of homes (old, typical and new) in 10 U.S. cities for a total of 30 different test simulations to decide what combination of energy efficiency and solar renewable generation makes the most sense for homeowners.
The conclusions are significant given that the residential sector consumes 22 percent of the energy in the U.S., and there are only two ways to structurally reduce a home’s energy costs: energy efficiency and energy generation using solar or wind.
The results of these 30 different home simulations are that climate, local utility rates and home condition are the biggest factors in determining what are the most cost-effective energy savings measures. Lighting retrofits are always cost-effective. Weatherization and insulation energy efficiency measures are most cost-effective in old homes in cold climates, but are not cost-effective in newer homes or in temperate climates, according to the report.
Basic building shell and ventilation energy efficiency measures are most cost-effective in cold climates, but have long paybacks in more temperate zones. 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. Solar thermal systems have good paybacks when the fuel source for hot water is electricity, the solar report says.
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. Numerous surveys validate that homeowners’ first goal is to save money when making efficiency and solar improvements.
However, there is a wide range of retrofit and energy audit options available to homeowners to reduce their energy costs, the report says. Home energy audit software has come a long way since the first punch card mainframe programs were used by utilities in the late 1970s in the U.S. One of the best programs available is the U.S. Department of Energy’s “Home Energy Saver” program, developed by the Lawrence Berkeley National Laboratory, according to the solar report.
This program has a comprehensive set of parameters that can be used to model all of a home’s energy usage, taking into account heating loads, cooling loads, hot water usage, lighting and appliance usage all adjusted for local climate and energy costs.
DOE program defaults were used for retrofit recommendations, savings and costs. No attempt was made to change the default recommendations and savings produced by the DOE program, although these defaults were adjusted for local energy efficiency and solar incentives where applicable.
Since the DOE program did not consider solar power or solar thermal retrofit measures, industry-accepted calculations were used to determine solar retrofit savings based on home electricity usage and hot water usage as modeled by the program. Local utility rates were used where possible, and adjustments were made to reflect marginal electric rates.
“In almost all of the U.S. housing stock built since the mid-1980s the ‘low hanging fruit’ of basic energy saving measures have already been harvested through energy efficiency regulations and solar rebate programs for energy efficiency measures,” said Sue Kateley, Executive Director of CALSEIA in a press release.
According to Kateley, for a typical home in the U.S., rooftop solar energy systems (electric and thermal), will generate six times more energy than can be saved with lighting, weatherization and insulation retrofits combined. Kateley said generating the remaining energy required by the home will have the biggest impact on reducing home energy consumption. Put simply, it is time for policymakers to reevaluate loading order priorities to ensure that the state and national policies to reduce energy consumption will be achieved in a cost effective manner.
“The economics for rooftop solar power systems have improved dramatically since 1980,” said Barry Cinnamon, CEO of Akeena Solar in a printing release. According to these 30 home simulations, the most cost-effective actions homeowners can take are to install energy efficient lighting and a rooftop solar energy system.
“We can’t conserve our way to energy independence; but fortunately, with affordable rooftop solar we can now generate much of the energy we need,” he added. The results outlined in the report are somewhat contrary to the “conventional wisdom” regarding cost effectiveness for energy efficiency and solar energy systems. However, these results are not surprising when one considers the range of U.S. housing stock, varying climate conditions and current costs of various retrofit and renewable energy options.
These results provide guidance for good national energy efficiency and solar policies that are consistent with homeowner economics. California Solar Energy Industries Association supports the widespread adoption of solar thermal and photovoltaic systems by educating consumers, supporting solar legislation and conducting business in a professional and ethical manner.