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Small Cabin Forum / Off-Grid Living / Design A Balanced Solar System For Me Please!!
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creeky
Member
# Posted: 6 Nov 2012 04:53pm
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I'm offgrid with a 1kw solar system with 6 l-16 style batteries for 1200 amp hours at 12v. During the summer I can do anything I want. But in the fall, our area is very cloudy... thanks to Sandy we just had a week of cloudy weather. So I ran the genny to a 75 amp charger 2 hours in the a.m. and 2 hrs in the pm. Hey, I get to watch a little tv at night.
This system will not support a fridge. And I want one. Propane is expensive. So I've bought 4 more 250 (80 cents/w!) watt panels and next year I will go to either a 24 or 48 volt system and move the 12v system to the workshop.
Mtn Don is your reality check. 12 L-16 batteries and 2kw panels is what you need to run a fridge and other mod cons.
two notes: 1. I generated 4kw/day with a 1k system comfortably all summer. Even today I generated 3.45kws. Yes the morningstar hooks into my network and I can obsessively watch the voltage/amps/charge current...
2. I did see a guy who insulated a normal 7 year old fridge, ran venting to a closet away from the fridge, and is saying he's got it down to 255kw a year. That's from 400. And I plan to do the same ...
But for your set up I'd go with the 5 day cooler and a bag of ice.
Nice pics. My but the fishing sure looks good.

morganplus8
Member
# Posted: 12 Nov 2012 11:42am - Edited by: morganplus8
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Well, the data is in!!!

I used my Kill-A-Watt for 7 days straight on my new mini fridge and we have actual data instead of guessing.

The control was a case of beer, I had to drink beer from the fridge in order to get it to cycle a few times. I was successful doing this, as were my friends! (I'm prepared to run this test again)

The average consumption of watts per hour was 18.6 watts over the period. This is quite a bit lower than we would have guessed. The reason is that the temp is set to the near freezing mark (75%) resulting in the beer being very cold without being silly about it.

So that means that I need 260 watts for my maximum time running the fridge (14 hours) and I will have 4 x 6V GC batteries running 12V making 5,400 watts available and using a 50% efficiency rate, that makes 260W/2,700W of supply or roughly 10% demand on the batteries.

With 200W of panels for 4 hrs of sun, I will easily be able to replenish those batteries with this system. It must be noted that the temp in the study was an even 70 degrees F so this number won't be the case in the summertime at the lake. Still, 10% consumption is very light for that one day a week where it has to deliver 14 hours of cooling.

Comments please!

MtnDon
Member
# Posted: 12 Nov 2012 08:57pm - Edited by: MtnDon
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Quoting: morganplus8
So that means that I need 260 watts for my maximum time running the fridge (14 hours)



I don't follow the 14 hour limit. 24 hours in a day, no? If it doesn't run for the other ten doesn't the contents warm up and then the unit has to run longer to bring the temperature back down? I feel I'm missing something; not on the same page.


If it's that that's all the time it will be used at any one time, a weekend or whatever I'd think an ice box or ice chest / cooler would be simpler.

Cooks Dock
Member
# Posted: 13 Nov 2012 08:12am
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Did you only try this with one case? If so, insignificent(sp) , more research required. Most quality studies require at least 1000 hrs of research.
(need a hand?)

morganplus8
Member
# Posted: 13 Nov 2012 09:15am
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MtnDon,

That's right, not a miss-print!! We show up at 8:00am and stop for a large breakfast, then drive an additional 10 minutes to the lake and fill the fridge with beer and steaks. The rest of the day we are out on the lake, or heading up the river for miles or traveling long distances to fish, water ski or whatever. No booze on the boat. By the time we get back (4:00 PM at the earliest) we are ready to kick back and relax! But around dust we are heading home and the place is locked up tight. The panels can charge the batteries for the next couple of days as there usually aren't visitors to the site daily. Until everyone is retired or until we buy a large houseboat, we aren't staying over night. Thanks

Cooks Dock,

You and I both know that this study clearly needs a Phase II, Phase III and a Phase IIIb study to make it viable. I'm glad you pointed this out to me but can you talk to my wife?

I travel down to the lake through the week just to work on the property as I have big plans for it with a huge boat lift and plenty of storage and automated power and water with a finished cabin that we can sleep over night in. This will take me a couple of years as I've required some head surgery due to a virus I picked up in Mexico. Next year is our big year to get things done!!!

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