U.S. Department of Energy - Energy Efficiency and Renewable Energy
A Consumer's Guide to Energy Efficiency and Renewable Energy
Small "Hybrid" Solar and Wind Electric Systems
 This building is powered by a hybrid wind and photovoltaic system.
Photo credit: K. Bullard, National Park Services.
According to many renewable energy experts, a small "hybrid" electric system that combines wind and solar (photovoltaic) technologies offers several advantages over either single system.
In much of the United States, wind speeds are low in the summer when
the sun shines brightest and longest. The wind is strong in the winter
when less sunlight is available. Because the peak operating times for
wind and solar systems occur at different times of the day and year,
hybrid systems are more likely to produce power when you need it.
Many hybrid systems are stand-alone systems,
which operate "off-grid"—not connected to an electricity distribution
system. For the times when neither the wind nor the solar system are
producing, most hybrid systems provide power through batteries and/or
an engine generator powered by conventional fuels, such as diesel. If
the batteries run low, the engine generator can provide power and
recharge the batteries.
Adding an engine generator makes the system more complex, but modern
electronic controllers can operate these systems automatically. An
engine generator can also reduce the size of the other components
needed for the system. Keep in mind that the storage capacity must be
large enough to supply electrical needs during non-charging periods.
Battery banks are typically sized to supply the electric load for one to three days.
For more information, see the following sections:
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