Re: [A/S] solar panels

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

Oliver,
 This has been described before, you might want to check out the VAC
archives at http://www.tompatterson.com.

Briefly, you need to start with your USAGE: minimize it wherever
possible by swapping light bulbs for lower wattage ones, change some of
the brightest and most-used fixtures to flourescents, and get a small
TV. (My little 5" color TV draws 1 amp as opposed to a 9" that would use
3 amps, for instance. I also changed some 1.3 amp bulbs for .5 amp
ones.)

Add up your usage numbers: this is a very easy task that should require
no more than one hour to measure your loads and estimate the hours of
usage. As an example, my own usage calculations showed about 20
amp-hours of consumption in a typical evening. My eMeter confirms my
usage at 10 AH for a "short" evening, including shower, to as high as 25
AH for a long evening spent reading and watching TV.

You'll want enough battery capacity to carry you at least 2 days without
discharging more than 50%. Two Group 27 "RV/Marine Deep Cycle" batteries
are good for about 170 AH, so you have 85 AH of capacity at 50%, enough
to run my trailer for 3 or 4 days.

THEN, figure out what you need for solar panels to replace this usage.
My own system incorporates 2, 75-watt panels that will give a peak
output of nearly 6 amps in direct sunlight. They'll actually do 4
amps/each, but only if they were clean and set at a 90 degree angle to
the sun, something that's not practical on a typical trailer
installation. You can figure about 4 hours of near-peak output + 4 hours
of half-output per day. My panels have usually replaced the night's
usage by 1:00 PM.

Mind you, I don't figure on running the furnace more than a very little
bit, as we do most of our boondock-style camping during the Summer. If
you plan on Winter camping, you'll need at least 4, 75-watt panels and
will need to incorporate a small genset in your system, along with a
good smart charger so you can minimize the run-time.

Some web sites:

http://www.rvsolarelectric.com
http://www.amplepower.com
http://www.amsolar.com
http://www.optimabatteries.com
http://www.westmarine.com
http://www.usbattery.com
http://www.gosolar.com
http://www.rvpowerproducts.com

Terry Tyler has a nice short treatise on solar power, but I can never
remember his URL. Fred Tinseth also has good, practical information at
http://www.phrannie.org.

                                                 <<Jim>>