Running fridge from spare solar energy

m30

Guest
Hi chaps,

just back from 2 weeks in France where we used a full 13kg bottle of lpg powering the fridge. I have 2 80w solar panels fitted to the MTTP regulator then 2 x 100 amp leasure batteries. I was talking to a chap who reckoned that my AES Dometic fridge would have an S+ connection for a solar input. It doesn't but it did get me wondering if I could divert the excess solar power to the 12v circuit of the fridge when my leasure voltage reaches about 13v?

I found a VSR (voltage sensing relay) which I may be able to make work, Ebay item number 110747372068

Dometic rate the 12v input for the fidge at 170w, but I presume that would be when you turn it on at first, rather than when its been running from the engine or gas and is already cool, then mid morning when my leasure batts are up to charge this relay would then divert the charge to the fridge which, being set on AES, would turn off the gas. If the power from the panels dropped it would then go straight back to gas.

I wondered if anyone else had done this, or had any help advice?

I also have 2 Load connections on my solar regulator, but I'm not sure if these supply spare power or supply the power your asking for at the expense of the leasure charge circuit.

cheers in advance

Stu
 
maybe a compressor fridge is the way forward,this has been discussed a few times and the consensus seems to be that the 12v element draws too much power for the lb s,even with solar
 
Yes! Compressor fridge,easier to use and with your set up , no problem. :hammer:
 
The fridge frezzer we have is one of the tall built in ones, so I'll not be swapping it.

Stu
 
Solar energy

The amount of power (Watts) you get from your solar panels will only be a fraction of what your fridge needs, so save your time and money and buy some more gas.

The terminal voltage of 13v is little indication of the state of charge. So even if your relay would come in at 13v and connect to your fridge, it would only be momentary, before sensing the high current drain that the fridge takes and disconnect again.

Fridges are thirsty for power and solar panels are OK for small stuff but don't be blown away by the claims and don't be taken in by just Voltage claims. its the Watts that do the business.

Hope this helps and saves you some dosh :wave:
 
I agree entirely with that Handsome Fella !. The relay would probably just cycle in & out all the time and achieve nothing. You say that Dometic claim 170W, this to me seems most optimistic, even more so in France & further south. Have you space to fit a Gaslow type refillable LPG system ?; good to go almost anywhere then, except Spain (no bulk LPG at garages).
 
Are you sure the gas function on your fridge is working correctly? That seems like an incredible amount of gas to use in a fortnight, after all the fridge only burns a lighter sized flame at most.
 
Seems a lot of gas to use just for a fridge/freezer, almost a kilo or 2 litres a day. We have a large Thetford fridge/freezer over the 3 years we have had the van (many of our trips are 2-3 months) our gas use works out at just under a litre a day. As we have the one refillable 11kg bottle we try to fill up after about 2 weeks.

We try to keep the freezer quite full, as a filler if there is space in the freezer we put orange juice cartons, the small ones are ideal & are handy as a lolly for when its hot.:tongue: Keeping the freezer full should make it run more efficiently.
 
Hi There m30

you've touched on my current "Hot Topic "

Check out my new thread on this forum....
Most efficient fridge on the planet !!


I'm onto this subject in a big way ! ;)

Gas absorption fridges become hopelessly inefficient when the outside temperature approaches 30 degrees C ,or above.

I'll post more stuff on this as soon as I've done more research and I have some news .
All the best

Oldtech

PS Kontiki is DEAD RIGHT !! .... the more full the fridge , the less energy is needed to keep
it all cool . It seems to go against common sense but it's a fact .... but I do mean KEEP
it cool .... not GET it cool.
 
Last edited:
hi, well i run 6 x 80watt panels and 600amp of batteries some times 800amp. this runs a two kw inverter and keeps my 240v household fridge working in the trailer.. .at home i park next to the house and turn off the trailer fridge but run my house fridge constantly by solar. given more sunny days i run the big freezer and a few other things as well.
could run a much smaller inverter in the trailer but i dont .
i used to have only 3 panels on the roof found this wasnt enough in winter .in uk . a few odd times in spain it was a problem and in portugal very often the inverter screamed .it doesnt now . in maroc three panels worked fine .
 
Thanks for the replies chaps,

my claim of using a full 13kg bottle may not be the most scientific, I swapped to the full bottle on the last day of our previous outing, and expected it to last the full 2 weeks. I suppose the wife must have done more cooking than I thought and of coarse we were warming water for showers.
The handbook for the fridge quotes 170w which is also the value on the 12v cable sheething on the back of the fridge.
My battery voltage regularly goes above 13v, but its difficult to work out just how much power the panels are capable of making as they only make it on demand (or thats the impression I get) so I thought it was maybe better to use the spare solar output rather than using lpg.

I could do with trying to workout the 12v current draw when the fridge is cold, but the way its wired through the relay makes it difficult to do. Which ever wire you disconnect causes the relay to drop out.

Also, the 170w claimed would be maximum, and would that be with the fridge turned up to the top, and would this figure reduce on a lower setting or will the 12v circuit be a fixed draw?

I'll keep thinking

Stu
 
Solar energy

Stu, forget solar power with your fridge. 170 watts is far too much to expect from your panels.

The way the 12v works on your fridge simply heats up an element and when freezing is required, it will be 170 watts until it is not required, it doesnt come down to a few watts as it cools down.

Remember also that to achieve anything approaching the solar panel manufactures claim, they have to have maximim sun (including pointing directly to the sun) and dont forget this is the time when the fridge needs to work hardest...

There is another factor which is important to remember, that to save energy in a battery is not energy efficient, so what you put in if you have any spare energy during the day, you will only get a proportion of it back when you need it.

You will find that people who claim that their solar panels does great things, either dont realise their battery has been charging from their zig unit via mains or alternator or just want to try and justify for themselves the money they have wasted in the first place.

If you are still stuck on going solar/fridge, you should really be calculating the size of a much larger roof on you van and the cost of covering it with panels but it might restrict access on most roads and you may take off when you get a speed up.:drive:
 
i can say mine as never had mains hook up in twelve years . never use sites ,or vary rarely .still dont use ehu. either its sun or if in an emergency to work welders and tools a grinder .but again never to charge the batterioes .its a big noisey diesel genny . but more panels required i would say. and live in spain in the winter .ha ha .
 
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top