solar panel expertise needed

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solar panel expertise needed

Postby gene so » Fri Mar 25, 2016 6:04 pm

Hello,
I am building a 5 1/2 x 9 camper to be towed behind my 4x4. I am building it primarily for remote locations. I am informed that for a week in the "boonies" two batteries would be good, and a solar panel for recharging batteries woud be money well spent. I will be having: a refrigerator , lots of lights and an air conditioner. I plan to mount the solar panel flat on my roof. So would my best choice be a 12v 60 watt solar panel? What brand would you recommend for the long term? I assume I would be running lines from the panel directly to my Trendlines inverter for recharging the batteries.
Thanks in advance.

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Re: solar panel expertise needed

Postby GuitarPhotog » Fri Mar 25, 2016 6:20 pm

You won't be running your air conditioner very long off batteries, any kind of battery! Check out the threads here about A/C and battery power. In general you need either shore power or a lot of battery capacity and a healthy inverter to run even the smallest A/C.

You need to add up all your loads then figure out how long you need to run them between battery charges, then you can determine how much solar panel you're going to need to replace the power you used.

I think you'll find that most folks around here run 80-200W of solar panel to supply power for a small trailer.

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Re: solar panel expertise needed

Postby Trevor57 » Fri Mar 25, 2016 11:44 pm

I agree with guitarphotog. Even a small ac unit can draw 50 amps @12v, which will kill a battery very fast. I plan to run a small ac unit in my trailer, but will hopefully run it off a yamaha ef2000 generator. With lights, and a small fridge i would get at least 300 watts of solar, and two large batteries.
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Re: solar panel expertise needed

Postby Socal Tom » Sat Mar 26, 2016 7:44 am

There are a few videos on YouTube that address it. A small 5k window AC unit will pull a few hundred watts just to spin the fan, and can pull almost 1000 watts with the compresser running. So I would think a 2000 watt inverter to cover the load. Assuming the ac unit runs 24 hours per day with the compressor on it would use up to 2000amp hours in 24 hours. You would want to double that for battery capacity, so that's about 4 batteries. To make up the 2000 amps in 8 hours would take 250 watts per hour, so probably about 500 watts of panels.
With the panels in place you could probably drop back to 3 batteries ( assuming your other loads were negligible. Or save weight and money with a generator .
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Re: solar panel expertise needed

Postby noseoil » Sun Mar 27, 2016 8:57 am

We had the same decision to make. A small fridge like a Dometic will use very little power once it's cooled down & operating properly, but the AC unit is basically out with a battery setup. You end up hauling around too much lead & the entire roof would need to be a solar panel, which isn't really a good solution due to weight. You would need to have about 350# of stuff hung on & in the trailer to make it work for 8 hours of cooling, just not a good solution. As was already mentioned, get a small generator of 2000 watts or more (45#) & run it as a support for the battery & solar system.

We used a PD-4045 to hook everything up & it seems to be the best solution. It does the 12 volt & 110 volt stuff, charges the battery if it's low & is about as easy to use as a system can be. With a good battery & an efficient type of fridge, you could probably get by with a single group 31 battery & 100-200 watts of panels for charging.

Add up all the loads, figure how many hours you will need to run, & then size everything accordingly. Add an extra % for a bugger factor, voltage loss, inverter loss & whatever & that's the system you will need.
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Re: solar panel expertise needed

Postby OverTheTopCargoTrailer » Tue Mar 29, 2016 12:23 am

No problem for $12,000 I can make his solar ac reality 5 x 9 is child's play.

But a Honda 2000 is only $999

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Re: solar panel expertise needed

Postby gene so » Fri Apr 01, 2016 10:42 am

Thanks for your invaluable insight;
My A/C will only be with shore type pwer. I will own both a Honda generator and mount a solar panel atop my trailer. Your combined input has undoubtedly saved me much time and frustration till I worked out a solution the hard way.

Thanks again,

Gene S.
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