| The Sun produces radiant energy by
consuming hydrogen in nuclear fusion reactions. Solar energy is transmitted to the earth
in portions of energy called photons, which interact with the earth's atmosphere
and surface. It takes about 8 minutes and 20 seconds for the sun's energy to reach
the earth. |
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| The Earth receives and collects solar energy in the atmosphere, oceans, and plant life.
Interactions between the sun's energy, the oceans, and the atmosphere, for example, create
winds, which can produce electricity when directed through aerodynamically designed wind
machines. |
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| Solar photovoltaic cells convert solar radiation into electricity (photovoltaic
literally means "light energy"; "photo" = light, "voltaic" =
energy). Individual cells are packaged into modules, like the one
shown at the right; groups of modules are called arrays. Photovoltaic
arrays act like a battery when the sun is shining, producing a stream of direct current
(DC) electricity and sending it into the building or sharing it with the grid. |
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| A weather station, located on or near the array, tracks
current weather conditions at the site. The weather station usually contains an anemometer
to measure wind speed, a pyranometer to measure the amount of solar energy
reaching the array, and a thermometer to measure the temperature. The
electronic signals from the weather station are transmitted to the data acquisition system
where they are interpreted and stored for collection on a periodic basis. |
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| The DC
disconnect switch allows professional
electricians to disconnect the photovoltaic array from the rest of the system. With
the switch in the "off" position, workers can safely perform maintenance on
other system components. |
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| The
inverter converts direct current (DC)
electricity generated by the array into alternating current (AC) electricity for use in
the building. Most electrical loads (energy-consuming devices like lights,
motors, computers, and air conditioners) in schools, homes and businesses use AC
electricity. |
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| The
transformer ensures that the voltage of
the electricity coming from the inverter is compatible with the voltage of the electricity
in the building. |
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| The AC
disconnect switch allows professional
electricians to disconnect the building's electrical system from the solar photovoltaic
system. With the AC disconnect switch in the "off" position, workers can safely perform maintenance on the solar photovoltaic system's components. |
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| The
electric meter keeps track of the amount of electrical
energy produced by the solar photovoltaic system and sends electronic signals to the data
acquisition system where they are recorded. Electrical energy is measured in kilowatt-hours.
How much energy is contained in a kilowatt-hour? We're glad you asked. Use our
calculator to find out. |
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| The data acquisition system (SolTrex logger) receives
signals from the weather station and the electric meter. It runs a computer program
to calculate and record the weather conditions and electrical output of the system, and it allows system owners and others to log in
and download information from home, work, or elsewhere. |
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| The electrical distribution panel receives
electricity generated by the solar photovoltaic system, combines it with other electricity
supplied by the electric utility company, and routes the energy throughout the building to power lights, appliances, computers, and other energy-consuming devices. |
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| Everyone enjoys the benefits of
solar electric energy without even thinking about it. The building or home owners also benefit by having a
portion of their electrical needs met by solar power, resulting in lower monthly electric
bills. |
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