Frequently Asked Questions / Solar
Under Construction
Q: How does Solar Power work?
A: Solar
panels transform the sun’s energy into electrical energy that can
power homes and businesses
Photovoltaic (PV) cells convert light energy into electrical energy,
as French physicist Edmond Becquerel discovered as early as 1839.
Most commercial PV cells are made of silicon
which is a semiconductor. Semiconductors are able to absorb some of
the light that hits that material and do something useful with it.
With pure
silicon all the electrons (negatively charged particles) in the
material are locked in the crystalline structure and cannot move.
The silicon in a solar cell is changed slightly so that it will work
as a solar cell by the deliberate addition of impurities. The bulk
of the cell is typically p-type material where a small amount of
positive donors are added to the silicon wafer; another layer of
n-type silicon is created on the cell with negative donors in order
to facilitate the movement of electrons, the basic electricity
carriers.
When light hits the solar cell, it makes
electrons move across the boundary and this creates an electric
current which can be drawn off and used to light homes by placing a
metal contact at the top and bottom of the cell.
Q: What is the difference between Solar
Thermal and Solar Photovoltaic?
A: Solar thermal principles are
applied to produce hot fluids or air.
Photovoltaic principles are used to
produce electricity. A solar panel (PV panel) is made of the natural
element, silicon, which becomes charged electrically when subjected
to sun light.
Solar panels are directed
at solar south in the northern hemisphere and solar north in the
southern hemisphere (these are slightly different than magnetic
compass north-south directions) at an angle dictated by the
geographic location and latitude of where they are to be installed.
Typically, the angle of the solar array is set within a range of
between site-latitude-plus 15 degrees and site-latitude-minus 15
degrees, depending on whether a slight winter or summer bias is
desirable in the system. Many solar arrays are placed at an angle
equal to the site latitude with no bias for seasonal periods.
This electrical charge is
consolidated in the PV panel and directed to the output terminals to
produce low voltage (Direct Current) - usually 6 to 24
volts. The most common output is intended for nominal 12 volts, with
an effective output usually up to 17 volts. A 12 volt nominal output
is the reference voltage, but the operating voltage can be 17 volts
or higher much like your car alternator charges your 12 volt battery
at well over 12 volts. So there's a difference between the reference
voltage and the actual operating voltage.
The intensity of the
Sun's radiation changes with the hour of the day, time of the year
and weather conditions. To be able to make calculations in planning
a system, the total amount of solar radiation energy is expressed in
hours of full sunlight per m², or Peak Sun Hours. This term, Peak
Sun Hours, represents the average amount of sun available per day
throughout the year.
Q: What are needed for solar power generation?
The four primary components for producing
electricity using solar power, which provides common 120 volt AC
power for daily use are: Solar
panels,
charge controller,
battery
and inverter.
Solar panels charge the battery, and the charge regulator insures
proper charging of the battery. The battery provides DC voltage to
the inverter, and the inverter converts the DC voltage to normal AC
voltage. If 240 volts AC is needed, then either a transformer is
added or two identical inverters are series-stacked to produce the
240 volts.
Picture on the left is a solar panel (PV).