Solar System

HOW SOLAR WORKS

Solar cells are converters. They take energy from sunlight and convert that energy into electricity. The conversion of sunlight into electricity is made possible with the special properties of semi conducting materials. Most solar cells are made from silicon the 14th element. Silicon is a "semi-conductor" or a "semi-metal" and has properties of both a metal and an insulator.



Solar cells alone cannot produce usable power. They need to be interconnected with other system components that ultimately conduct a specific electrical demand, or "load".

Photovoltaic (PV) systems can either be stand-alone or grid-connected. The main difference between these two basic types of systems is that for grid-connected systems, the PV system produces power in parallel with the electrical utility. It can feed power back into the utility grid if the onsite load does not use all of the PV system's output.

When the sun is shining, the direct current (DC) electricity from the PV modules is converted to alternating current (AC) by the power of an electronic inverter, and then fed directly into the site power distribution system where it supplies electric power. Any excess solar power is exported to the utility power grid and any shortfall is made up with electricity supplied by the grid. During non-sun hours, the site is supplied by utility power alone.



SOME USEFUL TERMS

PV Modules
A number of photovoltaic cells electrically interconnected and mounted together, usually in a sealed unit of convenient size for shipping, handling and assembling into tiles, strings and arrays.

Mounting Technology
Used to mount the PV modules in place. Depending on the application, the PV modules can be mounted on rooftops, on parking structures, covered reservoirs and in open fields.

Combiner Box
Where the electrical wiring from the PV modules are joined together in parallel to combine electrical currents.

Inverter
Converts the DC output of the PV system into usable AC output that can be fed directly into a site or building load.

Transformer
Used to step up or down the voltage emerging from the inverter to match the required voltage of the onsite load or the utility interconnection.

Load
The amount of electrical demand used at the site or building at any given time