fridge off grid.

[tim&fatima]

Hello Boys and girls,
I want to run our fridge/freezer on some kind of renewable energy, it is the only electric appliance that is constantly on.
is it viable?
I was thinking possibly of some kind of solar panel charging a car battery with a converter plug socket thingy that we could plug the fridge into.

as you can see i'm not very electrically minded. so any help would be appreciated.

[Martin]

...............simple answer "no"
Knew I'd gone through this before - here's a cut and paste from an earlier thread
"I'd suggest going at it from several directions..........firstly question the whole wisdom of having a fridge/freezer at all!
It wasn't so long ago that noone had them, and didn't feel at all hard done by -My aged Granny didn't have one for years, and got by extremely well with a cold larder - on a hot day tea did have the odd floating milky glob, but it was all part of the fun.....
Having decided that I'm an idiot, and that you really can't exist without one, try to minimise what you store in it - things like tomatoes and eggs do not belong in a fridge, so decide how little you actually NEED to store, and go for a suitably small fridge........
Last but not least, get a caravan type fridge that can run off either 12v or gas, then run it off gas! - Fridges and freezers use gobbets of power, there is no point using "high grade energy" (electricity") unless you absolutely have to....(electricity can be used for virtually everything, hence "high grade" - it's also expensive to generate and store, so only use electricity where there is no other substitute) "
Hope that helps!

ps just to run a typical fridge/freezer year-round using pv panels/batteries, you'd need a setup costing probably several thousand pounds......

[Clara]

We are fridge-free in the south of spain. We have a pantry and ice cream is a rare treat to savoured for the luxury it is!

Really it is not a problem to go without, we experimented with the pot-in-pot type last year (see main site for nev´s article), it worked amazingly well but we gave up on it because we didn´t have anything we needed to keep THAT cool. Though if I didn´t have a pantry it would be my first choice alternative.

I have lived with a regular size gas fridge and I hated it....it would get sooted up and fumey, made me too anxious about carbon monoxide poisoning to be thankful for it.

[Martin]

good point! I certainly wouldn't be happy with a gas 'fridge indoors unless there was a proper "exhaust" to the outside (as there is in caravan ones)
My experience of gas fridges is in caravan use, and they do exhaust straight outside, but I still take the precaution of having a carbon monoxide detector aboard as well........

[colhut]

ok, so changing the tack a little here, how practical would it be to use solar power to make a shed a little bit cooler ? The reason being is we plan to use a stone shed to store some of our harvest (apples, potatoes that sort of thing). We did pop a min max thermometer in there last summer and unfortunatley it was pretty much the same as ambient (well it was a couple of degrees down on the peak of the day but not great). So I was wondering how practical it would be to use solar to just make it a bit cooler. worth playing with or a non starter ?

[Martin]

You could run a fan directly off a pv panel, but I doubt it's going to do a lot of good unless you've got a whopper (expense! )
Generally, refrigeration/freezer units use ginormous gobbets of power - my usual advice is avoid using solar pvs , you need such enormous panels/battery that it just isn't economically feasible. Lots of lorries actually have another small diesel engine running the refrigeration unit, rather than using electricity, because it takes so much current!
I'd be tempted to look at a simple "wick" evaporative cooler - if for instance you had a corrugated iron roof, I'm sure you could work out some sort of sacking/wet sump device that would cool it well when you most need it
Hope that helps!

[caithnesscrofter]

pot in pot or zeerpot works well. We use it as well. http://www.6photo.org/images/zeer.jpg 3 months of the year we just sit stuff on the porch. Colhut, the cheapest and easiest method of keeping your stone shed at a constant temp is by berming up the back and sides with earth. Recently, weve started keeping stuff cool in the 'hovel' as it is lying empty and it is built into a hillside and maintains a cool temp all the time making it an ideal root cellar. http://www.6photo.org/images/thehovel.jpg
In my experience the more you try to incorporate electricity into simple tasks off grid the more difficult your life becomes. Where possible use natural energy without wires!

[Martin]

CC - couldn't agree more! Always go for low tech in preference, and use electricity only where nothing else will do the job (tvs, computers etc).
Definitely avoid trying to run energy guzzlers like refrigeration, cooking and heating by electricity

[The Riff-Raff Element]

This chap converted a chest freezer into a fridge that consumes 0.1kWh per day, which should be available from a fairly modest PV setup, though you would incur expense from needing an inverter to produce the necessary AC.

He makes a couple of very interesting points - for one that upright fridges are inherently inefficient since every time the door is opened the cold air pours out, something that would not happen with the chest design. Appearantly no-one has ever manufactured a chest fridge commercially. Looks like a neat opportunity for someone. I'd buy one that ran on 100 Wh pay day very happily!

Heres the link: http://www.builditsolar.com/Projects/Co ... fridge.pdf

[Martin]

IF it's that efficient, you'd need something like a 150w pv panel, plus suitable batteries, controllers and inverter to run year-round - circa £1,000 - 1,200 all-in!

[The Riff-Raff Element]

IF it's that efficient, you'd need something like a 150w pv panel, plus suitable batteries, controllers and inverter to run year-round - circa £1,000 - 1,200 all-in!

I wonder if you could easily replace the compressor with a 12 or 24v DC setup? Quite often things are supplied to run off 230v AC simply because that is what comes out of the wall socket. That would cut the cost.

You know, with a bit of engineering, this could actually work.

[Martin]

wouldn't make lot of difference - a good inverter is going to be around 90% efficient. If designed and built from day one as 12v it would make more sense (in other words, start with one designed for a caravan)

[MKG]

I'm surprised to read that a stone shed doesn't stay cool (not challenging it, just surprised). Is that down to the roof/door or is stone not what I thought it was?

[The Riff-Raff Element]

wouldn't make lot of difference - a good inverter is going to be around 90% efficient. If designed and built from day one as 12v it would make more sense (in other words, start with one designed for a caravan)

But caravan fridges are a little, well, small - 30 litre or so. I did find these http://www.sundanzer.com/Home.html which might be interesting.

Whatever next? Solar washing machines?

[Martin]

well.........at around £600 for a fridge, and a need of probably £5k worth of solar equipment to drive it, you pays yer money, and makes yer choice........
These are made by Texans, for Texans, where "small" is obscenely huge - they're designed for a Texan climates, attitudes, and probably appetites too!
Yes, running a fridge/freezer is possible from pvs, but to my mind borderline barking bats!