On the wall above this sign, on the roofs of the Science Center and the parking to your right are solar panels that contain many photovoltaic (PV) cells. These PV cells convert light from the sun directly into electricity.
The PV cells are made up of thin layers of phosphorus and baron imbedded semi-conducting silicon wafers that absorb light particles, called photons, from the sun. When the photons hit the atoms in the semi-conductive wafers, they knock loose some of the atoms' extra electrons. Now the electrons are free to move anywhere.
By attracting conducting wires to the PV cell the electrons flow away from the cell in the form of direct current (DC) electricity. To make electricity usable here or at home, it must be converted into alternating current (AC) electricity.
The Maryland Science Center solar system generates approximately 470 kilowatts per day in peak times. This is enough to power 14 average homes per day in the United States.
(Inscription in the image on the right) All electrical systems run normally, rain or shine, because the home stays connected to the utility grid.
Solar modules convert sunlight directly into electricity. That electricity is converted into house hold current through the inverter. It then can be used throughout the house to provide power for household appliances
and lighting.
The inverter converts the DC electricity generated by the solar modules into household AC current that can be used to power loads throughout the house. The home solar electric system connects into the existing household electrical panel. The utility meter tracks actual power usage and production, spinning forward when electricity is used from the electrical grid, and spinning backwards, generating a credit, when the solar system creates more electricity than is used.
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