What size (or output) solar panel to run a fridge?

Definitely need a battery.

To camp out unlimited time You need enough capacity in the battery to run the fridge for a day or two if no sun and you need enough capacity in the solar panel to put more into the battery than you are taking out over a 24hr period.

So you need to know approximately how many amp hours you are using per day. Then you need solar panel/s sized to provide that amount plus a reserve capacity to charge the battery if it gets discharged during cloudy days.

To just top up and extend your stay then it's different and it depends how long you want to extend.

heya emo, im going thru the same equations myself...

the thing i keeo reminding myself is batterys dont like to be discharged beyond as certain limit so while it may be ok to run your number against the batterys numbers you must leave a large reserve else ruin your battery...

there are systems gaurding against this but cost may make it better to stay at a resort 'powered by solar panel" ..lol..

seriously tho', depending on the amount of devices you wish to run will depend on the amount of batterys you will need...

i would be happy with 5x100a/h and three 65w+ panels with associated regulators, cabling, switch, guages etc.. about 4-5K but then I aint hard to please...

at the moment i am considering isolating a deep-cycle fridge battery from the accessories and devoting the solar panels to it, but thats only because I dont want to buy two-new batteries, just the $600 panel & regulator...

Let's try and keep in simple. Over a 24 hour period your fridge doesn't run fulltime. We have a 50l Waeco with a dual battery system and from my experince this setup is good for at least two days. When we are camped with access to the sun then we can count on an additional two days with our 2x30 watt solar panels connected to the second battery. I use an Anderson plug to connect the panels directly to the second battery. I also watch the charge in the battery closely and run the car if it needs a boost.

Peter

A 220 amp deep cycle battery and 2 x 64 watt Unisolars should do the trick..I used one panel and a 100 ah deep cycle battery on a previous set up and it lasted a day and a half , even producing 5 amps of power for about 6 hours ..Costs a small fortune to set up...but it works in my new rig and am a happy chappy..even though it cost big bucks !! (I have two 220 ah batteries )....but i run other things as well..tv, lights

Emo

I run a engel 40 litre frig and have used a 80 watt BP solar panel with a large 12 V battery for a extended piroid with no prob's.

Oooo solar panels...what fun!

You'd want an 80 watt panel as a minimum. An 80 watt panel will provide a peak of about 6 amps to your battery in full sun....remember 'peak' means best case scenario. For your calculations you want to work on 8hrs of sun per day max (less in the south). Therefore 8 x 6 = 48 amps back to the battery each sunny day.

Now if your fridge is drawing 60 amps per day then you are still losing a net of 12 amps/day based on the above. Therefore, for extended stays you're going to need a bigger panel (or 2) but with a 100amp hour deep cycle battery connected you should be ok for nearly a week with this setup. Fingers crossed the sky stays clear though!

A solar regulator is not essential if you are sure you are taking out more amps out of the battery than putting in but it is HIGHLY recommended. You can get a decent regularor for less than $100. A regular prevents overcharging of the battery.

Good luck.

Emo,

The replies you have received already are pretty comprehensive.

What you need to determine now is whether you will be running your fridge from a dual battery system and confined to the vehicle, or whether you wish to remove the fridge to place in a tent, or similar.

If you require more flexibility, a portable battery pack may be a better choice.
A portable pack of around 75 A/H or greater will run your fridge for a couple of days. If you then supplement this with a solar panel to put a charge back into the battery while it is running the fridge, this is possible.

A portable battery pack in an AGM style, is available from the following sources:-

www.sidewinder.com (an Advertiser on this site)
www.homeof12volt.com.au (Manufacturers of the Thumper portable battery system)

You will get a varying response as to the size of a solar panel required.
If you are looking for a lower entry cost solar panel solution, with a growth path to a higher output configuration if required, you can consider this:-

I run a BP solar 40 watt panel & regulator (cost under $600) connected to a 75+ A/H Thumper portable battery system. To double the charging input, you can couple another 40 watt panel to provide an 80 watt configuration. Another regulator is not required.
I have a 40 litre Engel with a maximum current draw of 2.7 amps backed up by the 40 watt panel and have been stationary for three days without a noticeable drain on the portable pack.

The thumper can also be charged whilst driving (or idling for that matter) via an in-car high capacity charge controller, off either the one vehicle battery, or connected to the auxiliary battery in a dual battery configuration. The portable battery system thus becomes a third battery.

This type of setup will give the best flexibility, it just depends on how you wish to set your configuration up.

Emo, such a simple question and so many vastly different replies lol

The only known facts are you use a fridge of unknown power consumption & you have a dual battery system.
The answer can be guessed at, but suspect you want an answer that can't be disputed and is guaranteed to work for you with-out any 'guesswork' involved.

Now the questions requiring answers are;
(a) what type & size of battery is your present Auxiliary battery
(b) are you going to roof mount the solar panel/s or use in a move-a-round situation(c) do you have a specific budget to work to
(d) do you know the actual power consumption of the Vitfrigio 42l fridge

Hi,emo
We have 2 115 amp Trojan deep cycle batteries in our caravan and 2 80 watt BP solar panels,we run a 40 litre engel and the normal fluro lights & tv, stayed in one spot beechworth for 3 wk's no shore power no problems.I hope this is some help, but doesn't come cheap but the old cliche you get what you pay for.
Cheers,Honest John

Why don't you do a search of this topic in the archives of this forum. It has been thrashed out many times over the last few years & there is heaps of info on the subject. Cheers