Solar panel systems come in a wide array of configurations, including panels that mount on your roof and panels that mount on poles outside your home.
Grid-tie solar systems connect to the local electrical utility’s grid to power the home at night or at times when the home is drawing more electricity than its solar system can produce. In some areas, grid-tie systems allow the homeowner to sell power back to the utility when their system produces a surplus.
Off-grid systems are designed to provide a home’s electrical supply without the need for a connection to the power grid. Such systems include a battery bank that recharges during the day and provides power for the home at night. These systems are ideal for remote properties.
The high cost of home solar systems once put them out of reach for many homeowners. But in recent years, solar leasing and power purchase agreements (PPAs) have made solar a much more affordable option.
Solar lease agreements let you lease a solar system instead of purchasing the equipment, helping to avoid high upfront costs. The provider installs a solar system which supplies power for your home, and you pay for the use of that system.
You may have also heard of “passive solar” systems which use the sun’s light directly to provide home heating or hot water. Passive solar systems do not generate electricity, but they can be employed to reduce a home’s overall energy use.
A geothermal system employs special pipes that are buried deep underground where the earth’s temperature is constant. Depending on the location, that temperature typically ranges from 50°–60°F, which is warmer than the outside temperature in the winter and cooler than the outside temperature in the summer. Therefore, a geothermal system can be used both to cool a home in the summer and to warm a home during winter.
When used for home heating, the system works by circulating fluid through the underground pipes to absorb heat. The warmed fluid returns to the surface where it is used to heat the home. There are various different types of geothermal systems, but they all employ a similar process of heat exchange.
In the summer, the process is reversed—the fluid absorbs heat from your home before being circulated underground, where the cool earth acts as a heat sink, cooling the fluid.
Like solar, the upfront cost of installing a geothermal system has been a barrier to widespread adoption of the technology. However, new companies that provide specialized financing have sprung up, putting such systems within reach of homeowners interested in reducing their energy use.
Micro wind and micro hydroelectric turbines.
Though uncommon, homes in certain locations can employ miniaturized wind or hydroelectric turbines to generate electricity. These systems may not be suitable for most homes, but they do demonstrate the level of innovation happening in alternative energy technology.
A variety of micro wind turbines are available, some claiming to generate up to 400 kilowatt hours of electricity per month, depending on conditions.
For homes located adjacent to a source of running water, micro hydroelectric turbines may be an option too. Such devices operate on the same principle as large hydroelectric dams, scaled down to serve a single home or small community. See more details on alternative energy at http://www.energystar.gov/index.cfm?c=rerh.rerh_index