| Commercial Photovoltaic Options |
| There are a few different types of photovoltaic
(PV) cells produced under many different brand names. You
can learn more about the technologies at the U.S. Dept. of
Energy's Energy
Efficiency and Renewable Energy website.
, but the most important fact is that all PV uses sunlight
to generate a
direct electrical
current. If you are using a PV system on a commercial property
you will want it to be “grid-connected,” so that
your building can run on conventional grid electricity when
sunlight is insufficient. |
 |
| First steps towards owning a grid-connected
photovoltaic system: |
| • |
Pursue building efficiency—seal leaky
ductwork, install efficient appliances and light
bulbs, and properly insulate your building. This
could reduce the size and cost of your system
by 20 to 50 percent. |
| • |
Assess your rooftop or property for an area
that receives direct sunlight for a minimum of
six hours on a sunny day. This area should face
due south, but this can vary by about 15 degrees
either way. Assume each kilowatt of PV will require
about 100 square feet of space |
| • |
Determine how much energy your building uses |
| • |
Determine what proportion of your building’s
energy you want to supply using photovoltaics |
|
|
| A Word about Sizing |
If you go to purchase a PV system, the first
question you’ll be asked is “How many kilowatts?” The
size of a PV system is given as the maximum direct current
(DC) output of the solar system in kilowatts. So, a 2 kilowatt
(kW) system generates 2,000 watts of DC electricity when
fully exposed to the sun’s rays. After this direct
current is converted to usable alternating current (AC)
through an inverter, the output is actually lower, about
1.7kW.
|
 |
System size is rarely given according to the
area of the panels or the total amount of electricity the
panels will generate over their lifespan. |
| |
|
A Grid-Connected Commercial
PV System
|
| This system: |
| • |
generates usable AC current after passing through the inverter |
| • |
is connected to the conventional electricity grid |
| • |
simply offsets energy that would normally come in through
the conventional grid with clean solar energy |
| • |
can send (and sell) power back to the grid if it is generating
more than the home requires and the local power company accepts
cogeneration |
| This system includes |
| • |
photovoltaic panels, number and size depend on desired
capacity |
| • |
mounting hardware and connecting cables |
| • |
inverter, to change DC into AC |
| • |
disconnects, required by law in accordance with local electrical
codes and utility requirements |
