Thread: Solar Panel Watts

my single 70 watter stays in front of my engle... but not forever.

the fridges draw is 3.5A nominal at 12v which is something like 50w but the solar panel doesnt charge at night and isnt in the best configuration your ever going to see.

The first thing you need to decide is whether or not you want the solar panel to run the fridge forever or if it just needs to extend your battery/s life for a day or three before it needs a full charge. Both options need to take into account the type etc of batteries you use.

My setup has two 65w panels, 200 amp/hours of gel batteries and a Waeco 80L fridge plus some fluoro and LED lights and a water pump. Plus I reposition the panels when I can for optimum charging.
I have no idea how long this setup will run under ideal conditions as the longest I have used it would be 3 days and the batteries probably would have done that on their own.

keep in mind that most fridges cycle at about 50% therefore they will only draw 50% of the rated amps.....or there abouts

my very old 65w solar panel averages 3.5amp when square on to the sun

depends how long you want to stay in the one place

along with my one solar panel, 2 x 100amp/hr batteries running 2 x engel fridges, a light or two and a water pump i have never run out of power.......how long without running the car, 2 maybe three day/nights

working on most cars running one 100amp/hr battery aux battery

you just need to play with the figures

usable 80amps not sure on this one
input from one 65 watter 8hrs @ 3.5amp = 28amps in
average usage fridge/lights 4amp/hr x 24hr = 96amps out

i would go the biggest that your budget will allow keeping in mind that you need to store the solar panel while travelling

Originally Posted by stew1236

Just bought a solar panel regulator (rated at 10 amps @ 14.2v ) , I asked what size solar panel I would need to power a 12v fridge ( evaKool 70lt ) the salesman said I would need two 65watt panel total 130watts to power an engle fridge ( he had never heard of EvaKool ) , anyway I think thats way to high , 65watts should be OK ?
any thoughts on this subjet would be welcome
Stewie
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Basic electrical formula is;

P (power in Watts) = I (current in amps) x V (voltage)

Just looked at the evakool website and the most they say the 55 liter fridge/freezer draws is 2.2 amps/hour. Apparently the 70 liter uses the same compressor so,

Power = 2.2 amps x 12 volts
= 26.4 watts.

But, this would be in an ideal situation and would'nt take into consideration additional current draw to pull the fridge temp down on start up or to maintain the temp setting after being opened heaps of times (you get through alot of beer when its 45 deg) or it being 45 deg outside. Too many variables.
But, if you were using the 65 watt solar panel to charge a deep cycle battery and had the fridge running off the battery then i dont think you'll have any trouble with just one 65w panel.

Drivesafe (member on here) is the guru on all things 12V though so he may shed more light on the matter.

Originally Posted by Utemad

The first thing you need to decide is whether or not you want the solar panel to run the fridge forever or if it just needs to extend your battery/s life for a day or three before it needs a full charge. Both options need to take into account the type etc of batteries you use.

My setup has two 65w panels, 200 amp/hours of gel batteries and a Waeco 80L fridge plus some fluoro and LED lights and a water pump. Plus I reposition the panels when I can for optimum charging.
I have no idea how long this setup will run under ideal conditions as the longest I have used it would be 3 days and the batteries probably would have done that on their own.

I think you should be getting more than that as thats what I get out of my configuration.. It might be a diffeence in positions tho as the last Time I ran it hard was up in townsville (which was also where I did the initial testing)

buy 65 watt if not enough get two ho har

Originally Posted by Blknight.aus

I think you should be getting more than that as thats what I get out of my configuration.. It might be a diffeence in positions tho as the last Time I ran it hard was up in townsville (which was also where I did the initial testing)

I don't know how long it will last if I just let it run. Three days is just the longest I've used it for. The batts weren't flat at the end of it. Not long had the panels and even longer since I have camped in the one spot for more than a few days.

Now I think about it, the panels were not even connected to my batts for much of the time. One of the other guys had batt issues so I had the panels on his batts for most of the time on that 3 day trip.
That is the benefit of not having them bolted to your camper or vehicle. They can be easily shared (and stolen) but packing them in the trailer is a pain.

I pop rivet mine to the top of the trailer, Its easy enough to remove if needed but difficult enough that anyone trying to would be easily noticed..., my configuration lends itself to me leaving the trailer as I have the main and aux battery in the car and then have a 100AH dual purpose battery in the trailer which supplements the one in the car. The fridge now lives in the car and flattens the aux battery in about a day and a half but its pretty rare for me to park up and not drive the car every other day, even if its only for runs for firewood which gets the car battery charged so my trailer battery and panel is only for supplemental power and lights off of the trailer.