solar electricity
TASTE of THE TouR: The Jerry and Michelle
Thompson home in Mundelein, Ill., boasts a 5.6-kilo-
watt photovoltaic array and a water-heating system
producing 50,000 gallons a year. Both systems were
installed by Solar Service Inc.
Solar ServICe InC.
Microinverters >> Some newer grid-tied systems
replace the large central inverter with several microinverters,
attaching one microinverter to the back of each Pv module.
Power coming off the module is now 230 volts aC and can
tie directly to the household service panel. a major advantage
is that if one module is shaded or broken, performance of
the rest of the system is unaffected. you can monitor the
performance of each individual panel on a home computer
or your smart phone.
Net metering >> your utility company may not offer
net metering. If it does, it typically does so under terms
determined by state law or by your public utility commission.
the rate the utility will pay for the power you sell will
therefore vary widely state to state and city to city. Some
utilities may pay more for power during high-load periods, as
in summertime late afternoons. Check with your utility company for details, or look up your local information at dsireusa.
org. If your utility doesn’t offer net metering, encourage them
to do so.
modules through a charge controller (also called a regulator), an electronic device that produces a smooth flow of
current at the desired voltage. from the charge controller,
the power can go to a set of storage batteries and then on
to the inverter.
today’s commercially available PV panels come in three
versions:
•;Single-crystal (or monocrystalline) modules are
currently the most efficient — that is, 1 square meter pro-
duces the most electric power. They must be mounted in a
rigid frame.
•;Multicrystalline (or polycrystalline) modules are
made of cells cut from multiple crystals, grown together in
an ingot. They are slightly less efficient than single-crystal
modules.
•;Thin-film modules are made by depositing or printing thin layers of materials on glass, metal or plastic substrates. They’re considerably less efficient, so you may need
to give them a lot of space to generate the same amount of
power. however, they’re now less expensive and, depending on the substrate, can be very robust and flexible. One
