Solar Energy Systems
Except for the manufacture of solar energy equipment, collecting and using solar energy results in none of the greenhouse or acid gas emissions associated with the combustion of fossil fuels. Moreover, sunlight is a widespread resource — according to National Renewable Energy Laboratory, the amount of it that reaches the earth each day is more than the planet’s 5.9 billion people would consume in 27 years. Solar systems collect current solar income — as opposed to solar income millions of years ago in the form of fossil fuels. Only cost and public perception limit the increased use of solar energy systems.

Solar energy can be passively collected through building designs that allow entry of sunlight and storage/reradiation of resultant heat; or it can be actively collected by systems that contain moving parts, such as fans, pumps, or motors. Active systems include those that collect and distribute (or store) solar-heated air or water for building heating and domestic water heating, and those that generate power.

Power generation systems include solar (photovoltaic) cells — semiconductor devices that convert photons from the sun into electricity, and solar power plants that concentrate solar energy to super-heat a fluid that is used (or stored for later use) to run a steam utility-run operations, but photovoltaic systems vary from utility-scale to building-scale to the scale of a single device such as a calculator or an off-grid light fixture.

Solar Water Heating
After reducing water-heating loads with efficient plumbing fixtures, solar thermal technology can be used to heat water for domestic, commercial, and industrial purposes. Even if a backup system is required, using the available sun to heat water will save money over the long run (with payback periods in the 6-12 year range), while reducing environmental impact. There are several different types of reliable, freeze-protected systems on the market. For backup water heating, select an ENERGY STAR® water heater model.

Excerpted with permission from Green Building: Project Planning & Cost Estimating, 2nd Edition, published by RSMeans.