How Solar Works
The sun’s light, as with all light, contains energy. Typically, energy from light produces heat upon hitting various surfaces. The best example of this is when sunlight hits a person’s skin the person will become warm. However, when light hits certain materials the energy can produce an electrical current instead of heat. This is what occurs during solar power.
A solar power system, also known as a photovoltaic (PV) system, provides power by converting the sun’s rays into direct current (DC), or electrical current. Direct current is the constant flow of electric charge in the same direction. Once in the form of direct current, the electric current is inverted into alternating current (AC). Alternating current is an electric current flow that reverses cyclically. The PV system converts the sun’s rays into electrical currents through the use of solar cells, or PV cells.
Solar cells are made from crystals made out of silicon. Normally pure silicon is a poor conductor of electricity. However, the addition of certain impurities, such as Phosphorus, creates a semi-conductor. The semi-conductors allow the silicon to conduct electricity by forcing electrons in the crystal to move around freely when exposed to light instead of just jiggling in place; thus, light absorption can flow around producing an electrical current as opposed to heat. The electric current produced is DC, described above. Generally, there are two types of crystals that can be used to produce an electrical current upon being hit by light. The first is monocrystalline, or single crystal. The second is polycrystalline, or multi-crystal. Monocrystalline are cut from a crystal that has grown in only one direction. These crystalline are more expensive to manufacture and typically have a higher efficiency than do conventional polycrystalline cells. Polycrystalline are cut from a crystal that grows in multiple directions. Solar cells produced from monocrystalline cells are typically more efficient.
Several individual solar cells wired together create solar modules. Additionally, a solar module consists of an aluminum framed sheet of durable, low reflective, tempered glass that has individual solar cells adhered to the inner glass surface. The individual solar cells are wired in specific series strings to increase the module’s voltage and electrical current. Ultimately, the modules are wired to a weather proof junction box which is permanently mounted to the back of the module. The junction box is where the module’s input/output connections are made. Several solar modules wired together comprise a solar panel. Solar panels are placed strategically on homes and businesses to create solar electricity. The solar electricity produced from the solar panels is fed into your meter and offsets the electricity demands in your home or business.
Simplified into four basic steps, solar power works as follows:
- Sunlight hits the solar panels, comprised of solar modules made from solar cells.
- The sunlight is converted into direct current electricity.
- The DC electricity is inverted into alternating current electricity.
- The AC electricity from the inverter flows through to your electric meter, offsetting the utility power you use.
When discussing how solar power works, the related concept Net Metering should also be addressed and understood. Net metering essentially means that if a solar power system produces more energy than you are using your utility meter will spin backwards. On the other hand, when your energy needs exceed the energy your solar power system produces you pull power from the utility as you always have and your meter spins forwards as normal. Your electric meter measures the net difference and your utility company bills or credits you for this amount. A credit does not mean you will get money from your utility company; however, it often times means you will be credited for future energy use from the utility company. In general, there are certain restrictions regarding net metering and the rules vary by state. In California, net metering is available. California’s net metering program has certain restrictions, but overall the net metering program does allow for customer solar power production being credited against utility power consumption.
