Photovoltaic (PV) modules make electricity from sunlight, and are marvelously simple, effective, and durable. They sit in the sun and, with no moving parts, can run your appliances, charge your batter- ies, or make energy for the utility grid. To use the energy from the array, you may also need other components, such as inverters, charge control- lers and batteries, which make up a solar-electric system. The components required are dependent on the system type designed.
System types include:
PV-Direct Systems
The simplest of solar-electric systems, with the fewest components (basically the PV array and the load) only appropriate for a few select applications, notably water pumping and ventilation – when the sun shines, the fan or pump runs
Off-Grid Systems
Off-Grid solar-electric systems can work anywhere. These systems operate independently from the gris to provide all of a household’s electricity.
Grid-Tied Systems with Battery Backup
This type is very similar to an off-grid in design and components, but adds the utility grid, which reduces the need for the system to provide all the energy all the time.
Batteryless Grid-Tied Systems
Also known as on-grid, grid-tied, utility-interactive, grid-intertied, or grid-direct. They generate solar electricity and route it to the loads and to the electricity utility grid, offsetting a home’s or business’ electricity usage.