Solar system

[goldgeezer]

I just bought 2 100 watt solar panels and a new mini refer the refer is 115 volts at 1.4 amps and in my teardrop i will probably run 2 12 volt lights no more than 2 hours a night and maybe portable DVD player for 2 hours so im wanting to know battery i will need i was thinking of a 70 ah would be enough want some opianions on this please i will run a 750 watt inverter and charge controler to. everyones input needed

[Gladtobehere]

I'm no expert but I gotta agree with Slow. You may get a few hours runing a small rerigerator, but you will never recharge the batteries completely even in all day, direct sunlight. Better to park in the shade and use a cooler.

Also, batteries and many solar panels are quite heavy so they are much better suited for stationary installations.

[jss06]

In this case the fridge will be pulling 161 Watts. if your cells are running at full capacity and your inverter is 80% efficent then you can only supply 160 watts of power. You are starting off at a loosing proposition.

Throw in that about a third of the time the solar cells will not be producing any power and you will quickly drain the battery.

Since the fridge is 110v and not 12v your battery draw is actually about 16 amps after running through the inverter. At this draw the battery will be dead in a couple of hours.

[jss06]

Just to get through the night you will need about 400ah of battery because you cannot completely drain a battery or it is useless.

Now say you get 8 hours a day of power from your solar cells. During this time not only do you have to run your equipment, you also have to recharge the batteries you drained.

[bdosborn]

Lets run some back of napkin type numbers to show you were you're at with the panels and the fridge:

Here's the amp-hrs you'll need just for the fridge:
16A*24 Hours*50% duty cycle= 192 amp-hrs per day

Here's what your two 100 watt solar panels will harvest on a perfect day, tilted at the sun and using a PWM controller.
13.9 amps*5.5hours full sun= 76 amp-hrs per day

You're upside down on your usage and your harvesting. That's the reality of trying to run a regular fridge while boondocking, you need a lot of battery and a lot of PV panels. The two panels you have will more than keep up with the lights and DVD player but you're better off using an ice chest if you want cold beer while you boondock.

There are 12V refrigerators that only use 1 amp-hr instead of 16 amp-hrs but they're spendy.

Bruce

[bdosborn]

Also, batteries and many solar panels are quite heavy so they are much better suited for stationary installations.

Hmmm. That's a surprise to those of use who are using PV systems on our trailers.

560 watts and it keeps going up


Bruce

[goldgeezer]

First of all thanks everyone. Ive decided to use refer with hook ups only like when im at the coast and still put the solar panels to use on my trailer build but only for the lights and maybe 12 volt DVD

[48Rob]

Your fridge can still be used as an ice box if you have no hookups by freezing 1/2, 1 gallon, or odd shaped containers of water.
You could also use block or cubed ice, but then you have to deal with melt water.
I always bring a dozen or so (small) bottles of water, frozen, so we have drinking water that we're used to on camping trips.
The small ones melt pretty fast, and help keep the cooler cold on the way there.

Rob

[eamarquardt]

There are 12V refrigerators that only use 1 amp-hr instead of 16 amp-hrs but they're spendy.

Bruce

I've picked up four Norcolds (exact same as Engles) off of Craigslist for about the same as one new one. Don't tell my wife though.

Cheers,

Gus

[goldgeezer]

im not out much money the refer was on sale for $46.00 and the 100 watt solar panels i only had to give $50.00 each so im good!

[Bogo]

There are 12V refrigerators that only use 1 amp-hr instead of 16 amp-hrs but they're spendy.

Bruce

I've picked up four Norcolds (exact same as Engles) off of Craigslist for about the same as one new one.

The 12 and 24VDC compressor based chest stype refrigerator/freezers sip power in comparison to a regular home one, and also do a very good of job of refrigerating or freezing. Because the top opens, you don't dump your cold air all over like an upright refrigerator does. Second, they usually have more insulation.

In the long run I want two. One to use as a freezer, and the other for a refrigerator. If I had only one, I'd use it as a freezer, and freeze down a couple 1/2 gallon milk cartons of ice a day in it for cooling a Coleman 5 day Extreme cooler. Two gallons of ice in the Extreme, and one freezing down in the freezer. Swap the most melted ones in the cooler for the ones in the freezer in the morning so the initial freezing is using energy directly from the solar panels. The rest of the freezer could store meat and frozen meals for a couple week trip as well as a tub or two of ice cream.

BTW, I'd use ice instead of chemical freezer blocks because the ice can serve as emergency water if needed. When kept in clean closed plastic milk jugs it should remain clean for direct drinking. If you start with distilled deionized water it could be used to top off a battery or radiator with no issues.

[Bogo]

im not out much money the refer was on sale for $46.00 and the 100 watt solar panels i only had to give $50.00 each so im good!

Get a charge controller for the solar panels, and use it to charge up a battery bank. You want to charge controller so the solar panels don't overcharge the battery. As for battery size. The larger the better. The smaller the percentage you draw down a battery, the longer it will last. You don't want to ever draw down a deep discharge battery more than 80%, and it will last allot longer if you only draw it down to 50% or less. A 100Amp hour battery bank should run an Engal 45 refrigerator and a couple LED lights a few hours a night for 2 to 3 days with no recharge and not use over 80% of it's charge capacity. With solar recharge during the day you should never see it get to discharged unless you have a long period of cloudy days.

BTW: I'm a fan of more battery capacity than needed as you always find uses for the power if available. I also charge camera batteries, laptops, phones, etc. with mine.

[TPMcGinty]

im not out much money the refer was on sale for $46.00 and the 100 watt solar panels i only had to give $50.00 each so im good!

That is an awesome price on solar panels! Where did you get them? Are there any left?

[GerryS]

This is where all the people who said you don't need solar ask where to buy

Solar probably will never be a solution for hard core boon-docking, but it might extend the trip

[Shadow Catcher]

Gerry The periods we have boondocked the solar on Compass Rose worked perfectly and we did not stint our use. Even at Big Basin Redwoods State Park our 185W high voltage panel kept up with the demands and powered our Waeco refrigerator. It is a high high voltage and I used an MPPT converter. A 12V (typically putting out about 17V is inactive in low light, which is 100% of the time at Big Basin. Ours puts out 12.7V in moon light (full moon) not enough usable current but it gives and idea of how this works. The other half of the equation is is conservation, LED lights, computer case fan in place of a Fantastic Fan not using resistance heat appliances....