Alternative energy installation services specify and install photovoltaic, wind energy, and other distributed energy production systems for commercial and residential applications. They may also specialize in green technologies such as biofuels, biomass, geothermal, tidal power, and wave power. Typically, alternative power or green energy is derived from sources that do not deplete natural resources or harm the environment. By contrast, renewable energy may have a significant environmental impact, as is often the case with hydroelectric dams. Nuclear power is sometimes described as a form of alternative energy, but the designers and builders of nuclear power plants are generally not included in listings of alternative energy installation services.

Alternative energy installation services may specialize in systems that provide solar energy, solar power, or photovoltaic energy. Solar installers specify products such as solar water heating systems (SWH); solar electric, photovoltaic, or PV systems; and building integrated photovoltaic systems (BIPV). Solar water heating systems consist of collectors, a controller, and a storage tank. Solar electric systems or PV systems consist of modules with photovoltaic cells that generate direct current (DC) electricity when exposed to sunlight. An inverter is used to convert this electricity to alternating current (AC) power. Solar energy, solar power, and PV alternative energy installation services that specify and install building integrated photovoltaic systems (BIPV) are also available. BIPV products both generate electricity and function as building materials, usually roofing or shingles.

Alternative energy installation services may specify and install wind turbines, windmills, wind farms, and other wind energy systems for residential and commercial use. Smaller wind turbines are often horizontal-axis, propeller-type systems. They consist of a rotor, generator, support structure, and tail. The rotor has two or three blades, and converts the wind’s kinetic energy into rotary motion that drives the generator. Vertical-axis wind turbines are also commonly available, but more expensive. Some wind energy or wind power installation services specify and install windmills, machines that can generate electricity and pump water up from a well. Other wind power installers design and install wind farms, a group of wind turbines or windmills that produce “green power” electricity. Alternative energy installation services that install wind towers and residential wind turbines are also available.