pianotuna
Regina, SK, Canada
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Hi all,
It was my first chance to see how my solar panels fared with snow this morning. Time was 10 a.m.
There was less than one centimeter of snow and output is zero.
Batteries were at 12.4 volts as I forgot to turn off the inverter over night--it was 12.5 last night.
I'm doing a load test by running two heaters with a total wattage of 2127 watts for 30 minutes. Voltage dropped immediately to 12.0 measured at the charge controller. I have deliberately plugged them into the same outlet--I want to know what those 15 amp breakers will do. (i.e. it should have tripped immediately and it did not). I did not think to plug in my kill-o-watt meter--oh well!
I'm combining this with a heat rise test--RV was at 0.9 C. The outside temperature was -0.9 C
Results:
The breaker failed to trip under a load of 2127 watts. I feared that would be the case.
Battery voltage after 30 minutes under load displayed as 12.0. When the load was removed the display immediately bounced up to 12.2 volts
Battery voltage at charge controller after 5 minutes of "rest" was 12.3 volts
Temperature in the RV was 6.5 C. Outdoor temperature was -0.4 C.
Please feel free to interpret the results--and to post your own results to this thread.
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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Chris Bryant
DeLand, Florida, USA
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I'm not surprised by any of the readings- 2127 watts is only 17 plus amps @ 120 volts, and there is enough safety margin built in to cover that slight over current.
Covering solar panels is about the only way to turn them off  .
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smkettner
Southern California
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Batteries are run down a bit from leaving the inverter on. OK and the solar has some snow preventing recharge.
I am thinking remove the snow and get the batteries back up. But instead you run an electric heater test using the batteries 
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pianotuna
Regina, SK, Canada
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Hi smkettner,
My rv goes into storage--and I have no access to it at night--so with zero output from the solar panels it was the perfect time to test the batteries out a bit.
smkettner wrote:Batteries are run down a bit from leaving the inverter on. OK and the solar has some snow preventing recharge.
I am thinking remove the snow and get the batteries back up. But instead you run an electric heater test using the batteries
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bobofthenorth
Somewhere in North America
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I'm at a complete loss to know what the OP thinks he is testing. In the first place, in Regina at this time of the year, he'll be lucky to get any output at all from his panels due to the angle of the sun. If he thinks he can provide any significant heat to his rig with solar under any conditions he is dreaming.
My advice - make sure the batteries are charged and completely disconnected before you put it in storage. Then forget about it until spring at which time he should charge the batteries again before trying to use the rig. By the time spring rolls around in Regina the sun will be high enough to provide some solar output.
Better plan --- screw the storage --- head south immediately!
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atreis
Yellow Springs, OH
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Unless you're trying to see how long your batteries will last when camping in the winter (not very long if you have to run the heat, especially if they can't recharge at all), this test makes little sense to me.
I live WAY south of there and left my batteries hooked to my 115W panel throughout the winter last winter with only parasitic loads, and the batteries still reached less than 50% charge at one point because of snow on the panel. This winter I made sure they were fully charged and disconnected them.
If you need power for brief periods in the camper (for instance, to run lights so that you can check for mice - NOT for running the heat or any other significant load) you can (briefly) hook one of those car jumpstarter doohickies that has a battery in it into the 12V outlet in the camper.
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sonicsix
Jemison, AL
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Chris Bryant wrote:Covering solar panels is about the only way to turn them off .
This is why I installed two 20 amp switches inline when I wired my panels. Never know when I might need to turn them off...
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MNtundraRet
Bloomington, MN
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Well Don; I learned a lot.
1) If it snows overnight on the horizontal solar-panels on your roof you are out of luck. Amp-hours=0 until you get rid of the snow.
Park the motor-home facing EAST, and hang your 256 watts of panels over the passenger-side. With vertical panels no more snow removal and the sun angle will be about right for where you live.
2) Your 30 minute experiment with the electric-heaters would use 170 amps in an hour, or 85 amps for your 30 minute test. Your 256 watt solar- panels will replace about 17 amps at peak sunlight each hour. Since you are good for about 5 peak hours of sunlight average during the winter months. If you get a sunny day you just might replace the 85 amps you used up.
3) You used up about 10 to 12% of your house-battery bank during the test which would be about 0.1 volt drop in battery voltage after rest so testing equals theory.
4)Circuit breaker: In hot weather they can trip at 80% of rating due to heat. At freezing (0' C, 32' F) temperature the opposite may be true and they might not trip at 17 amps.
5) Heaven help us! Cabin-fever is already setting in.
Mark
Mark & Jan "Old age & treachery win over youth & enthusiasm"
2003 Fleetwood Jamboree 29
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pianotuna
Regina, SK, Canada
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hi bobofthenorth,
The snow melted and the panels started to recharge the batteries. I took the unit back to the storage facility. It will be interesting to see what has happened in one weeks time--I'll be making another trip then.
I don't know what the "high" output was today but I did note it was 2.5 amps at 4 p.m. on a very overcast day.
bobofthenorth wrote:I'm at a complete loss to know what the OP thinks he is testing. In the first place, in Regina at this time of the year, he'll be lucky to get any output at all from his panels due to the angle of the sun. If he thinks he can provide any significant heat to his rig with solar under any conditions he is dreaming.
My advice - make sure the batteries are charged and completely disconnected before you put it in storage. Then forget about it until spring at which time he should charge the batteries again before trying to use the rig. By the time spring rolls around in Regina the sun will be high enough to provide some solar output.
Better plan --- screw the storage --- head south immediately!
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sh410
Northwest
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let's hope your batteries don't freeze!
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