A Solar PV system typically consists of 2 basic components:

The PV Array

Electricity is generated by solar cells, which produce an electrical current when light hits them. Individual solar cells are grouped together into a solar “panel” or “module”. Then, several solar modules are grouped together to form a PV array.  An array is sized according to how much electricity production is desired.

The Inverter

 Power produced by the PV array is direct current, or DC power. That power needs to be converted to alternating current, or AC power, before it can power electrical loads in your home or business or be connected to the utlity grid. The inverter is the heart of the system and is responsible for performing this conversion safely and efficiently.

Intro to Photovoltaics

Types of Solar Photovoltaic systems:

Grid-tied Battery-less Systems

Grid-tied systems are configured so that the power they generate can be fed directly into the utility grid. Whenever the systems are active, the electricity produced is not stored; instead it is delivered directly to the loads in your house or building or to the local electric company.  If your PV system is producing more electricity than you are using, the electric company then uses “your” power to meet the general demand and you receive a credit for the electricity that your system produces.  When this occurs, your utility meter will  spin backwards, a very rewarding experience!  This process is called net metering, and in most states utilities are required to allow solar PV systems to net meter.  The advantage of grid-tied systems is that they are the simplest and most economical systems available.  They do not require batteries and are more efficient than battery systems.  A disadvantage is that when the utility power is out, the solar array will not provide electricity to your home or business.  This is required to protect the utility workers repairing the outage.   

Grid-tied Battery Systems

Grid-tied systems with batteries work very similar to the grid-tied battery-less systems described above with a small, but important, difference.  They are configured so that the energy they generate can be stored in the batteries and delivered to the loads in your house or building.  While a grid-tied battery system will still have net metering capability, when the utility power is out, your critical loads will be supplied from the batteries. 

Off-grid Systems

As the name implies, off-grid systems are not connected to the public utility grid and are often referred to as “stand-alone” systems. During the day, the electricity generated is used to either power loads or charge storage batteries. At night, power is supplied by the energy stored in the batteries. When the sun comes up the next day, the cycle begins again.  Off-grid systems are typically found in remote homes, weather stations or radio sites and parks.  These systems can also be used to supply electricity to vacation homes that are not connected to the utility grid. In developing countries, off-grid systems frequently represent the only solution to supplying remote villages with electricity. The demand for these types of systems is extremely large. To date, approximately two billion people worldwide still live without electricity in regions far away from public utility grids.