RV FEATURE
Until 2010, solar capacity was very costly. The
general advice back then was to fit only what was
needed, and to have as much battery capacity as
feasible. Since then, however, solar capacity fell
in price by almost 90%. Virtually all solar modules
are made in China although (the Chinese-based)
Canadian Solar also produces solar modules
in Canada.
The five top brands have long been Trina, Yingli,
Jinko, Suntech and JA Solar. All are readily
obtainable in Australia, and some are sold under
other brand names.
Most such solar modules produce an actual 140-
180 watts per square metre around midday in
most latitudes. A safe guide is to assume about
400 – 630 watts per day in most parts of Australia,
except way down south during the three main
winter months.
Also, since 2010, battery pricing has escalated. A
good 100 amp-hour AGM now costs $300 upward,
yet only 50% of its capacity can be used without
substantially shortening its life below 500 such
cycles. Lithium-ion LiFePO4 batteries are still
about three times that price, but if 80% of their
capacity is routinely used, their life span is about
2000 cycles, almost 5.5 years if, improbably,
used daily. (‘LifePO4’ is that type of battery’s
chemical makeup. It is a generic description, not a
trade name.)
LiFePO4 batteries also maintain virtually constant
voltage down to the maker-advised minimum
of 20%. A 100 amp-hour LifePO4 is thus the
equivalent of a 130 amp-hour AGM. In essence,
when buying rechargeable batteries, one is
actually paying for usable amp-hours.
AGM batteries accept higher charging rates
than do conventional deep-cycle lead-acid
batteries. They are damaged by over-voltage,
so it is necessary to ensure that the obligatory
solar controller protects against this by having an
AGM setting option. All good brands do.
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