Renewable energy is gaining momentum as building administrators and homeowners face down issues like rising gas costs, environmental concerns, and regional regulations around energy use. Let’s take a more in-depth look at one of the most popular forms of renewable energy generation: solar systems.

Broadly, solar systems are sets of equipment that collect energy from the sun in the form of light, which is very diffuse and hard to harness, and turn this into energy that is usable for human activities. There are two types of solar energy systems: active, and passive.

The most widely known reusable energy generation system is active solar. These are the solar panels that are often visible on residential rooftops or in open fields at renewable energy generation plants. Solar photovoltaic panels are made of many linked-together photovoltaic cells in series, each of which generates a small portion of the total electrical output. This is also called a “solar array”. One photovoltaic cell can be expected to produce around 0.5 Volts. The cell consists of a glass lens on top, which due to its transparent nature barely inhibits the light reaching the layers below, while also providing structural stability, ease of cleaning, and protection from the elements for the rest of the cell. Below that, there are conductive metallic strips, which allow electrons to flow out of the cell to be used as electricity. Below that layer, there are three layers: N-type silicon, the depletion layer, and P-type silicon. When solar photons hit this stack, it causes electrons to flow from the P-type to the N-type silicon, and out through the conductive metal wires. This process turns solar rays into useful electrical current. These solar arrays are often mounted together on structures that raise them up above ground level, allowing them to avoid shadows and harvest as much energy as possible.

Passive solar energy generation works much differently. The energy is not generated to be transported as electricity, but is generated in or near the spot that it will be used as thermal energy. Passive solar systems can take many forms, but a common one is using dark colored plastic to cover an item that should be heated. Examples of this include black-sided tanks on composting toilets, which use solar energy to kill bacteria and turn waste into safe compost. Another example is dark swimming pool covers, which absorb light from the sun and radiate that into the water below, heating it to a comfortable temperature. Ideally, in cases like the latter, the fluid to be heated should be circulated past the thermal collection surface to increase the speed of thermal radiation to the entire body of fluid.

Solar energy systems are notable for their scalable nature, which makes them a great candidate for residential installation at the scale of one or several buildings. Many property owners are increasingly turning to solar for its environmental and cost-saving impacts. Subsidy programs and sell-back agreements may be available through your publically- or privately-owned utility provider.