Solar Setup in Van

[Ryca]

Hi folks,

I am looking for some help rigging a solar panel up in my camper van. It will power an auxiliary battery system, which will run dome lights, a small fridge etc. The biggest draw on the battery will be the 12v fridge, drawing 8amps.

I picked up a panel which I hope will be sufficient: Shell Powermax Ultra 85-P http://ecee.colorado.edu/~ecen4517/c...ellSQ85_US.pdf

And am wondering what kind of controller to get. I was told to look into MPPT controllers -- keeping cost down is a goal, but if it will be the difference between running the fridge or being out of power I am willing to shell out extra $.

I would appreciate any help, as this is totally foreign to me !

Thanks so much !

[Wy_White_Wolf]

12V * 8A * 24Hours = 2304 WattHours.

What's the duty cycle on the frig?

Start by returning that panel. You're going to need 4 to 6 (or more) - 250Watt panels.

WWW

[jimindenver]

If the fridge pulls 8 amps contentiously, you are in a world of hurt. I have a small absorption fridge pulling 8 amps, it will pull down a 95 Ah battery in 5 hours just to let you know what kind of battery you will need over night and on cloudy days. Much more doable on gas if that is a option. Otherwise the fridge alone will pull close to 200 Ah and a 80 watt panel will not provide.

MPPT in this instance is a waste of money as the tiny additional energy you will get is not worth the cost, buy another panel instead.

You need to start by knowing how much power you use on average. Switch the dome lights over to inexpensive LEDs to conserve where you can. Once you understand how much power you need, you have a better idea how much to provide. Things that will be considered is how much and what kind of battery and what fits on your roof. The best controller will interact with both the batteries and panels well.

If the fridge is not your basic 3 way RV fridge and has to be on 12v, I suggest checking out a small 120v fridge to run off of a inverter. harder to set up but it will use less power in the long run as it isn't running continuously.

[Sunking]

Never going to work as it would take 1000 watts of panels and a 600 pound battery.

[Ryca]

Thank for the feedback, that is what I feared.

[Amy@altE]

As others said, the fridge is the deal breaker, is it on and drawing 8A constantly? If so 8A x 12V = 96W x 24 hours = 2304 watt hours(wh). 2304wh / 4 sun hours / .67 system losses = 860 watts of solar needed. However, as others suggested, if you can replace the electric fridge with a gas fridge, and make sure the dome lights are LED, and don't try to power anything that makes heat or cold, you could use the 85W panel. It has a short circuit current of 5.45 x 1.25 = 6.8A. You need at least a 7 amp charge controller to use it. Don't bother with MPPT for something that small. A Steca SOLSUM 8.8F would be fine, or a Morningstar SS-10-12V are good and inexpensive.

[Ryca]

As others said, the fridge is the deal breaker, is it on and drawing 8A constantly? If so 8A x 12V = 96W x 24 hours = 2304 watt hours(wh). 2304wh / 4 sun hours / .67 system losses = 860 watts of solar needed. However, as others suggested, if you can replace the electric fridge with a gas fridge, and make sure the dome lights are LED, and don't try to power anything that makes heat or cold, you could use the 85W panel. It has a short circuit current of 5.45 x 1.25 = 6.8A. You need at least a 7 amp charge controller to use it. Don't bother with MPPT for something that small. A Steca SOLSUM 8.8F would be fine, or a Morningstar SS-10-12V are good and inexpensive.

Thanks for the tips on the controller !
I got the panel @ a Garage sale for a good price ($40) - and might run it anyways to handle the lights.

The fridge has the capability of switching from gas to 12v, however im looking @ being away from propane fillups for up to two weeks @ a time ( a surf expedition down the baja peninsula ), and need the gas to cook on ! Its a tricky situation. The battery charges off the alternator while driving, but i anticipate spending days without turning on the ignition...


Thanks again all

[jimindenver]

I'm not sure what you will be cooking or cooking on, but we fill our two 20 lb tanks once a season. We run the fridge and water heater, do all of our cooking including the oven on cooler days, and heat the trailer to 74 degrees day and night. That alone uses considerable propane in the cooler seasons but we haven't run out yet. We usually camp a month a year with two trips being cooler. With temps ranging from the 20's to the 30's at night, the furnace runs at night spring, summer and fall.

The fridge alone uses little propane or battery power.

[Sunking]

The fridge has the capability of switching from gas to 12v, however im looking @ being away from propane fillups for up to two weeks @ a time

So what is your point? A tiny 20 pound tank will last a couple of months Most RV's I see use a 40 pound tank.

[Ryca]

Im thinking of running that sunsaver controller -- I am trying to find a lcd/led readout that would tell me the status of my battery. Ive found a few volt meters, as well as amp... Do i need to run both to determine the batteries charge? Is there a recommended meter that I could wire in with a display which would indicate my batteries charge level?

[Ryca]

So what is your point? A tiny 20 pound tank will last a couple of months Most RV's I see use a 40 pound tank.

My tank is relatively small, about 2.7 gal. ( im not sure how that translates into LBS ? )

[Ryca]

Im thinking of running that sunsaver controller -- I am trying to find a lcd/led readout that would tell me the status of my battery. Ive found a few volt meters, as well as amp... Do i need to run both to determine the batteries charge? Is there a recommended meter that I could wire in with a display which would indicate my batteries charge level?

Would this be effective ?

http://www.amazon.com/Battery-Indicator-Solar-Panel-Golf/dp/B0027NRBUA/ref=sr_1_5?s=automotive&ie=UTF8&qid=1418805295&sr=1-5&keywords=battery+meter

[Sunking]

My tank is relatively small, about 2.7 gal. ( im not sure how that translates into LBS ? )

2.7 gallons x 4.2 pounds = 11 pounds

[Amy@altE]

If you want a meter, jump up to the Morningstar ProStar 15M. It will give you the battery voltage and the amps of the panel as it is charging.

[thastinger]

You need a setup like most TT have. Mine has 2 30Lb tanks on the trailer tongue and a valve to switch between tanks. The only things that run on 12V are the lights, radio, fridge control logic board and the heater fans.

If nothing else, you could buy a 20lb tank and bring that along.