How Solar Electric Systems Work

Sunlight can be changed directly into electricity using solar cells. Solar cells are made from silicon or other semiconductors and are manufactured in thin film layers. When sunlight strikes a solar cell, the photoelectric effect causes the electrons in the semiconductor to become energized therefore generating electric current. Solar cells, also called photovoltaic (PV) cells, are arranged together in a solar panel. These panels are grouped together to form an array. A typical home will need one, two, or three array of panels.  The array is connected to an inverter which converts the Direct Current (DC) of the PV modules to Alternating Current (AC). Once the DC is converted into AC, the electricity is ready for the use in a home or business.

A typical residential home will need about twenty to thirty panels in order to sustain the home’s electricity usage.  This requires about 350sqft to 500sqft of space on the rooftop or on the ground free of shading.  Ideally, the solar electric system that is designed for the home is aiming to eliminate the majority of the bill or the bill entirely.

Connecting To the Grid

Most solar electric systems are considered grid-connected homes or buildings, meaning that the home or building is receiving energy from the local utility company.  A grid-connected solar electric system will be linked with the utility company so electricity can be fed back and forth when needed.  If the solar electric system provides more power than the customer uses, excess electricity is fed back into the grid and the utility’s electric meter counts backwards. This is referred to as “net metering”.   This is done to ensure that the home or building will have constant source of energy whether it is self generated by the PV system or drawn from the utility grid.

Typically a solar electric system is sized accordingly so just the right amount of electricity is generated on an annual bases.  For example, the accumulated energy that you sent back to the grid will be ready for you to use at night when your solar electric system is not generating any new electricity.  During this process, you can see from your meter or your monitoring system that your electrical usage is in fact moving backwards.  At the end of each billing cycle, you will notice that your bill is very little because you have not needed to purchase extra electricity from the grid.