ENERGY
From page 18
connecting of the system,
from a dealer specialising in
large off grid farm and
housing systems.
It is a 48V system, with locally
manufactured components,
except for panels (although
panels are also now manufactured in South Africa),
comprising the following:
K 12 x 250W polycrystalline
solar panels (which give 12 x
250 = 3kW), in four clusters
of three panels (750W)
connected in series, with
each cluster's cabling going to
A bank of 24 locomotive batteries delivers
48V DC to an inverter which converts the
current to 220V AC in the house
believes he should have
forked out an additional
R10 000 on a 3-phase
inverter, especially if he
the maximum power point
about R3 000 each, comwishes to run heavy equiptracking charge controller
pared to a solar 12V 105Ah
ment in his workshop, or a
(MPPT).
cell at R1 500 to R2 800
three-phase pump, for
K A 60A MPPT charge
each.
example.
controller, (which Smit
The lifetime of the 2V cells is
And, in future he would like
believes is a bit small for the
expected to be ten to 15
to purchase an extra bank of
system, pointing out that a
years with that of a 12V cell
batteries which will allow for
3kW system, on 48, will give
only two to three years. The
more optimal use at night.
one 62,5A.
downside, says Stephen, “is
Smit points out that an extra
K Storage is by 24 x 2V milthat the whole battery pack
bank of batteries will expand
19, 650 Ah Benoni-made
has to be replaced at the end the life of batteries. “It does
locomotive batteries, joined in of its lifetime, so one should
not give you more total power
series for 48 volts.
budget for it.”
… all it means is that your
K These in turn feed a 10kW As a rule, says Stephen, “if the back-up is bigger. Your total
pure sinewave inverter.
batteries are 100Ah you need panel output is what you
Apart from the imported
a solar panel larger than
have available. If you use
panels, the fact that these
100W. Given that the 2V cells more than this, your batteries
items are locally manufacare 650Ah units, using three
will be depleted”.
tured, Stephen hopes that
solar panels in series gives
For the system installed by
service levels will be high,
750W.”
Stephen is capable of
commenting, “You don't get
“And, the good news is that
handling the extra set of
the same service on cheaper
solar systems are covered
batteries without changes, or
imported Chinese products
under my building insurance
even two sets for that matter,
that have to be replaced.”
policy.”
the theory being that the
The 2V cells cost Stephen
In retrospect, Stephen
Continued on page 22
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