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May 2nd
2004
I spent a few hours today helping our friend Robbyn get a solar panel
installed on the roof of her Casita.
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Up to this point she had been moving her panel
around to take advantage of the sunshine. When she was boon docking
in Quartzsite she had her solar panel and charge controller set
out on the ground near her batteries. When her Casita was
in storage, she set up the panel on the table near the window to
prevent it from being stolen and to take advantage of whatever
light was available to keep the batteries charged. |
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I worked with her to get the panel re-located to
the roof of her casita.
We had to manufacture a few "L" brackets and
scrounged together all of the parts we needed from her stockpile
of assorted aluminum scraps.
I created brackets similar to the ones that I put on the bus
so that Robbyn could tilt the panel toward the front or rear of
the Casita to take full advantage of the sun. We mounted
it flat so that she is not forced to park the Casita in any
particular orientation to the sun. |
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We chose to put the panel at the back of the
Casita right above the battery. There was already a hole
there where a TV antenna used to come through the roof.
Her set up is a lot less complicated than ours, so she doesn't
need all the heavy cable and a huge charge controller.
We did the calculations and figured that the run of wire from
the solar panel to the battery was about 10 feet. That
allowed us to use 14 gauge wire for the majority of the run for
the small 3-4 amps that the solar panel puts out. |
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With only one 60 Watt panel she can get away with
a very inexpensive controller. I'm not sure where she got
it from, but it appears to be a simple automatic sequencing
charger that shunts the incoming power to the ground when the
battery voltage reaches 14.2. It then switches back to
full power again when the battery voltage drops to about
13.2. It seems to be working perfectly fine to keep her
battery in good shape.
This simple method does not allow for equalizing, but if the
battery bank is sized correctly for the solar panel(s) this
device makes a very simple, effective and pretty much error
proof system. |
We installed several disconnects - one at the panel, one at the ASC
and another one at the battery. That should give her some
flexability to work on the system later if necessary. There was
already a fuse at the battery, so there was no need to install one.
I could see where this simple system could be upsized. One ASC
for each solar panel and each one tied into the battery bank. If
one of the ASC's failed, the system would continue to work for the most
part... I'll have to look into the cost of these units for future
comparison. You don't get a fancy readout or 3 stage charging but
it seems to do the job without too much of a voltage drop... |
