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Batteries,
the heart of the system
Typically, the greatest
attention of any of the solar electric system components will be
devoted to the batteries. If batteries are neglected, degradation
can occur at a fast pace. A battery industry wag once stated, "few
batteries die a natural death, most are murdered." The following
information relates to only lead acid batteries.
Cycling,
Deep vs. Shallow
A cycle in the battery world occurs when you discharge a battery
and then charge the battery back again to the same level. The battery
is designed to absorb and give up electricity by a reversible electrochemical
reaction. Ho deep a battery is discharged is termed "depth
of discharge." A deep cycle occurs when up to 80 percent of
the battery capacity is discharged and recharged. Deep discharge
batteries have thicker
plates of active material which have less
overall surface area. This type is preferred for a PV system.
The discharge
depth will have a good deal in determining the battery life. Shallow
cycle our deep discharge batteries for the most cycles.
Four
Charging Sources
Flexibility and independence are among the most significant benefits
of a battery-based electrical system. Batteries can be recharged
in a number of different ways.
- Generator and/or
utility power, connected to the AC input of most Trace inverter
models, turns the inverters into battery-charging power houses.
For battery charging, many people use a generator and the unique
three-stage, built in, battery chargers, which are designed
by Trace to ensure fast and complete battery recharging. This
combination results in up to a 3/4 reduction in running time
for the generator. And while the generator is charging batteries,
it can be powering heavy loads such as power tools, a washing
machine, or a water pump. Renewable energy sources can also
be harnessed to take the place of generators or utility companies
as a source of energy.
- One of the world's
best battery chargers is the sun. Solar electric charging systems
are the essence of simplicity. Photovoltaic panels (also known
as PV modules) produce DC electricity whenever the sun is shining.
Because electricity is being produced at a molecular level (photons
in light cause a spare electron in the silicon atom to move
and create an electrical charge), there are no moving parts
to wear out in a solar electric, or PV generator. Hundreds of
thousands of people worldwide rely on the sun to keep their
batteries charged. With solar electric panels your charging
system can be expanded at any time simply by adding more panels.
- The wind is another
extremely viable source of electrical power for battery charging.
A will-sited wind generator can provide ample power for remote
homes and other off-grid applications. Because wind is a more
intermittent resource than sunlight, battery banks in wind powered
systems are often larger in order to accommodate the intervals
between windy periods. Wind power is often used in conjunction
with PV modules. Having two sources of renewable electricity
makes for a very reliable and flexible battery charging system.
- Yet another common
source of battery charging is microhydro (also known as minihydro).
This method of electricity production directs falling water,
such as a stream, through a small turbine, which in turn is
connected to a generator or alternator. The actual amount of
power generated by most microhydro installations at any one
time is relatively small, from 100 to 2500 watts. Because the
power is being generated around the clock, however, most microhydro
systems far surpass similar sized PV systems in the total amount
of power they generate for storage and use.
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