question resolar power

[big daddy]

g'day to all my caravan and camper trailer friends....

i have a 21ft caravan and i'm thinking about adding a solar panel as an additional power source.

the van is fitted with 2 x 100ah deep-cycle batteries.

if anyone can help me, what size solar panel should i use to keep the charge up to the batteries?

i'll only be using the batteries (for lighting and the fridge) while camping where generators aren't allowed.

any suggestions?????

big daddy

[megatexture]

80 - 120 watt would be heaps but make sure you do your research you get what you pay for and get a good regulator

[BillsGU]

If you are running a 12 volt fridge you probably want a bit more than 120 watt. I have two 130 watt panels on my caravan. You are better off with two smaller panels than one large one (say 250 w) as I have had reports of the larger panels breaking on top of caravans. Apparently they can't flex as the roof moves - so they break. You should also be looking at a dual regulator (such as a Morning Star). This type of regulator lets you adjust battery priority (the percentage of charge the panel supplies to each battery). If it was my set up, I would have one battery only for the fridge and the other battery for everything else. Then I would set my regulator up at 90/10 (90% to the fridge battery and 10% to the other). You can change the percentage regulation as required. It takes a bit of trial and error depending on your set up and 12 volt usage. I have NEVER run out of power - even with a few overcast days. I have not used my generator in years and (if I can find it) I am thinking of selling it.

[HammerBuilder]

Yeah like bill says multi panel, just as a quick note my 90ltr fridge on 12v is rated at 175watts so you may want to look into your fridges usages & calculate the total watts needed.
2x100 amp/hr batteries should be fine but if you have room stick at least 2x90watt panels as these will flex fine on the roof & are a manageable size. As for twin regulators not sure as if batteries are wired right they are like water tanks if 1 goes down the other will feed it till they are the same level. But I supose you could seperate 1 for fridge/ 1 for lighting but I think this would put more stress on the fridge battery if not kept topped up sufficiently by solar or other means, I mean 1 to 3 days may be fine but if its weeks you stay at places I'd keep both Batteries in parralel together this will be 200amp/hrs as compared to running 1 100amp/hr flat then having to switch over if it does run flat that is.
Once again check your specs on your fridge n see what calculates better for you. I use gas on my fridge most of the time as its very economical
& if I run out then switch over to battery if needed then if staying longer I just hook up to car n charge batt this way for 20mins if theres no sun.
cheers n hope it works out ok for you.

[zd30elgrande]

Really need to know what wattage your fridge draws? Is it 12volts or do you have an inverter? and what voltage are your batteries IE 2 x 6v or 2 x12v etc? That should tell us if the batteries are wired in parrallel or series.
Cheers

[mudski]

The way I see it. As big as your budget will allow. I have 190w tri-folding panels from Ebay. Was about $400 from memory. I still need to change the controller as its a piece of poo but that on the cards....

[threedogs]

Bigger is not always better with panels, first you need to work out approx. what amps you would use on a daily basis, or amps per hour used

[muletopia]

Yeah like bill says multi panel, just as a quick note my 90ltr fridge on 12v is rated at 175watts so you may want to look into your fridges usages & calculate the total watts needed.
2x100 amp/hr batteries should be fine but if you have room stick at least 2x90watt panels as these will flex fine on the roof & are a manageable size. As for twin regulators not sure as if batteries are wired right they are like water tanks if 1 goes down the other will feed it till they are the same level. But I supose you could seperate 1 for fridge/ 1 for lighting but I think this would put more stress on the fridge battery if not kept topped up sufficiently by solar or other means, I mean 1 to 3 days may be fine but if its weeks you stay at places I'd keep both Batteries in parralel together this will be 200amp/hrs as compared to running 1 100amp/hr flat then having to switch over if it does run flat that is.
Once again check your specs on your fridge n see what calculates better for you. I use gas on my fridge most of the time as its very economical
& if I run out then switch over to battery if needed then if staying longer I just hook up to car n charge batt this way for 20mins if theres no sun.
cheers n hope it works out ok for you.

That sounds like good advice and the way to go

[muletopia]

That sounds like good advice and the way to go

Granted that for fixed panels, but if camped under a shady tree come summer what are the thoughts on moveable ,fold out panels. These can be put out in the sun and facing the sun, perhaps not possible with the fixed panels. Opinions?

[threedogs]

Never empty your fridge it will work too hard, have wine bladders of water to fill in the space your fridge, it will work more efficiently. An 80 watt panel will return 4.5 amps approx per hour.
Work out your needs A 160 watt panel will not be returning 9 amps back into your battery/batteries. First work out what your usage. Solar will work every day except when raining and not 100% when cloudy. do your home work or you could be just buying yourself an expensive tropical roof for your van. and buy decent regulators. Its a big investment get it right the first time. I run an 80 watt panel and have for over last 10-12 yrs never had problems with flat batteries, and even better now as I've changed all my lights to LED.
And chase the sun as you'll find fixed panels not as efficient, they will work on cloudy days just not as well.
Up on the Murray or out in the Simmo you should be able to stay there till you you run out of food and water, you'll still have plenty of battery left