Photovoltaics = Photo (Light) + Voltaics (Electricity)
We are experienced providers of all types of PV systems.
Below is a model and explanation of a
system, the type most commonly found in our area. We also
design and install
type systems for Residential and Commercial use.
Photovoltaic technology has come a long way since Bell Labs produced its first functional solar cell in 1953. But the basic theory is still the same...
The sun’s waves hit a photovoltaic cell and excites the electrons within layers of the cell. The excited electrons jump back and forth, creating electricity. This electricity is captured by wires running through the PV cells and sends the electricity into your home. The electric current generated by PV cells is direct current (DC), or the type of current used in batteries. Most of the appliances in the United States run off of alternating current (AC), or the type of current that comes over power lines. If you decide to use conventional appliances in your building, the electricity from the solar cells will now go into an inverter where it will be turned into alternating current. From the inverter the electricity will then be used by the appliances and systems in your home or go out into the grid.
Photovoltaic cells are almost always arranged on a panel to form a solar module. Modules are then linked in series to form what is known as a solar array. The size of a solar module or array is most commonly given in terms of its peak power production, or, Watts-peak (Wp or just W.) Let’s say, for example, that Solar Incorporated makes a 100 Watt solar module, which is comprised of 50 cells at 2 Watts each. This module generates 100 watts of electricity when fully exposed to bright sun. If 10 of these modules were combined in series, they would form a 1000 watt, or, 1kilowatt (kW) solar array.
Once you have decided to use photvoltaics, you must choose whether its power will be:
a) connected to the conventional electricity grid
b) connected to the building and a series of batteries that will supply power during hours without sun or remote location
c) a combination of the two
If the solar array is supplying a home with access to the electrical grid, it is recommended that the system be grid-connected (also called grid-tied). In a grid-connected solar system, all electricity generated is sent directly to the grid. Your electricity bill will reflect your net electric usage or the difference between the amount of electricity your solar panels produced and the amount of electricity you used.
Solar photovoltaic panels produce direct current (DC)
electricity. Direct current is one type of electrical
current; alternating current (AC) is another. In the United
States, the vast majority of residential and commercial
appliances and equipment use AC current. Power plants
produce AC current. The vast majority of DC current usage
is for devices that use batteries.
An inverter is a key component of a photovoltaic system and is used to turn DC current into AC current. Electricity can then be directed back to the electrical grid. In states like California with net metering laws, the power company must purchase electricity from the PV array owner.