Looking for ways to save money and lower their carbon footprint, many baby boomers think about retrofitting their homes to be more energy efficient. Despite the economic downturn, many are also interested in investing in renewable energy systems like solar panels and even home-scale wind turbines.

According to Curt Bradley, a solar contractor in Concord, California, people over 50 are the fastest growing segment of the home-scale renewable energy market. “These are people who are retiring and looking to stabilize their expenses,” he explained. “Some of my clients had electric bills that, after installing a renewable system, went from $200 a month to $200 a year.”

That said, the up-front costs of home renewable energy systems are high. Depending on size and other factors, a solar hot water system costs anywhere from $6,000 to $10,000 for a family of four, while wind or solar electric systems range from about $6,000 all the way up to $80,000, including equipment and installation.

The good news is that the economic stimulus legislation Congress passed in February significantly beefed up federal tax credits for residential solar and wind energy, which can be taken for systems installed on any residence in the United States that is used by the taxpayer, including a second home. Under the new law, the 30 percent federal tax credits for the cost of installing a solar-electric, solar hot water, or wind energy system have no cap—whereas previously they topped out at $2,000 for solar and at $4,000 for wind.

In California, rebates are available for residential solar systems under the California Solar Initiative, passed in 2006, which set a goal of having 3,000 megawatts of solar power installed in the state by 2016. These rebates vary depending upon where you live, as the state calculates how much power your system will generate based on climate and other factors.

California also has a patchwork of municipal and county incentives, including rebate programs in Marin County, San Francisco, and elsewhere. In addition, a number of local loan programs make it easier to pay for a solar installation by adding the cost onto the homeowner’s property taxes spread out over a 20-year period. These loan programs are available in Berkeley, Palm Desert,