SOLAR PV
Photovoltaics = Photo (Light) + Voltaics (Electricity)
We are experienced providers of all types of PV systems.
Below is a model and explanation of a
Grid-Tie
system, the type most commonly found in our area. We also
design and install
Battery-Back-Up
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.
The Grid
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.