Solar Energy

Solar Energy: Solar power systems convert sunlight to heat and electricity. Solar Energy is Philadelphia’s most abundant renewable energy resource. Enough sunlight falls on the earth every hour to power all nations for an entire year.  Find out how you can you use this abundant energy! There are three basic ways to use solar energy:  day lighting, space and water heating, and electricity generation.  While solar photovoltaics (PV or solar panels) get most of the attention, solar thermal systems (e.g. heating your water with the sun) are even more cost effective and potentially more universally applicable.

Solar Water Heating
Solar collectors gather the sun's energy, transform its radiation into heat, and then transfer that heat to water or  fluid. Solar water heating in Philly is extremely cost effective as a water heating fuel, and can supply 60% of the annual hot water needs for an average family.

Solar Space Heating: Solar energy is an extremely effective space heater, as you know if you’ve ever gotten into a car which has been left sitting in the sun with its windows rolled up. Passive solar heating is the most cost effective way to do this, and requires southern exposure. Solar radiant floor heating is also extremely cost effective, using solar hot water as the heat source in a system of tubes that runs under the floor. These floors are usually masonry, such as tile or concrete to transfer the heat evenly.  Solar radiant floor systems are practical for new construction and retrofit situations.

The U.S. Department of Energy’s website is loaded with useful information, starting with:  While our region has a number of solar companies and contractors, most specialize in PV. For a list of solar water heating and space heating contractors, contact Angie’s List at:

Photovoltaics (PV): A photovoltaic (PV) system converts sunlight into electricity. A PV system is made up of several photovoltaic solar cells. An individual PV cell is usually small, typically producing about 1 or 2 watts of power. To boost the power output of PV cells, they are connected together to form larger units called modules. Modules, in turn, can be connected to form even larger units called arrays, which can be interconnected to produce more power, and so on. In this way, PV systems can be built to meet almost any electric power need, small or large.

PV systems usually include an inverter to convert the direct-current (DC) to alternate-current (AC) electricity. PV systems may also include batteries for backup, or they can be grid-tied. These items are referred to as the balance of system (BOS) components.

Combining modules with BOS components creates an entire PV system. This system is usually everything needed to meet a particular energy demand, such as powering a water pump, the appliances and lights in a home, or—if the PV system is large enough—all the electrical requirements of a community. 

Because solar energy has no emissions, is very quiet, and can be sized to match the end load, it is a very popular and versatile energy source. Solar PV has come down dramatically in price and improved in efficiency in the last few years, to the point that it is now less expensive than conventional power in some states. For a list of PV contractors, go to