The optimal
renewable energy solutions will utilize a combination of Solar and
Wind resources. Solar electric, heated air, and hot-water
generation techniques can be coupled with Wind Turbines to take full
advantage of renewable energy resources.
Wind
Turbines and Solar PV cells use the same storage (battery/grid),
charge control, inverter, and monitoring equipment, so realizing
additional power savings by adding a wind turbine is an obvious next step
in many areas.
PV Systems with Generators
What about situations in which remote or non-grid-connected power is
needed, but that power must always be available — for example, to keep
vaccines cold, or a rural clinic's lights on, or communications equipment
running continuously? Or the times when users know they'll occasionally
need a larger amount of power than a PV system can supply alone — say, in
a national park camping ground, where it's difficult to predict how much
power will be needed? In those cases, PV is still a practical choice. We
just need to add an electric generator that can work effectively with a PV
system to supply the load.
During the day, the PV modules quietly supply daytime energy needs and
charge batteries. If the batteries run low, the engine generator runs at
full power — its most cost-and fuel-efficient mode of operation — until
the batteries are charged. And, in some systems, the generator makes up
the difference when electrical demand exceeds the combined output of the
PV modules and the batteries. See our case study on a telephone signal booster for a good example of
such a remote application.
Systems that use several types of power generation have the advantages
of each one. Engine generators can produce electricity any time. So, they
provide an excellent backup at night or on cloudy days for the PV modules,
which produce power only during daylight hours. The advantages of a PV
system are that it operates quietly and does not pollute. As to the rather
high initial cost, we can select a smaller PV system if we operate it with
a generator.
Where no other form of power generation is available, the PV array and
the battery storage have to be large enough to supply nighttime electrical
needs. However, having an engine generator as a backup means fewer PV
modules and batteries will be necessary to supply power whenever it's
needed.
Including a generator makes designing a PV system more complex, but
it's still easy to operate. In fact, modern electronic controllers allow
these kinds of systems to operate automatically. Controllers can be set to
automatically switch generators, to supply AC or DC loads, or to do some
of each. Wind generators, small hydro plants, and any other source of
electrical energy could also be added to make an even larger hybrid power system.