powering an inverter

[vwalan]

at the moment i have 3 linked together then down to the reg, later i will link the other 3 together and down to a different reg. i like to keep options open ,if one lot goes down the other should work. fingers crossed. you should be able to cut the freezer down . i visit all those countries and getting supplies isnt too difficult.main thing is having icecream or making lolly pops when in the desert . hee hee. we did make a kind of icecream last winter it was good enough to pass . dont forget to get a bottle refiller off e bay and the adaptors . good bit of kit. though in spain its cheaper to use spanish bottles . should you get to morocco there bottles are only about 4.50 to exchange .good job you hanve plenty of room. by the way i will just link the regs in on a positive -neg to a bank of bats. cheers alan

 

[pauldmallett]

Read this book

Hi, If you want to understand the subject you should all read this book.. Motorhome Electrics by Collyn Rivers, this is mostly about solar and related electrics.
Cavavan and Motorhome Books by Collyn Rivers
This guy really knows his stuff depite being Australian and has more books on solar and campers.

 

[mildred]

just googled this, and it says that the freezer will use 1KWh per day, whatever that means! [...] .so if it uses 1KWh a day how big a solar panel would we need, and if we got 2 big leisure batteries for the solar panel to charge, how big should they be?

Sorry - I'm late into this thread and I see the OP has given up on the idea of a big freezer, but for the record and for those who come looking for an answer to this:

A 1KWh appliance is normal household domestic kit. I work on off-grid installations with big panels and I wouldn't be keen to see such an item in the inventory. You can get A++ rated stuff that comes in at a half of that. Fill unused space with a polystyrene block and you do better still.

How much PV? If this was a fixed installation in the South of England I'd be saying 1.5kW. Just running the inverter 24/7 will "cost" you half a kWh a day.
(If anybody knows of a more efficient 5kW inverter please let me know) . 5kW? Yes - that's what I'd spec for this kind of system. vwalan gets away with half of that, but from his posts we know he's dead careful and understands his system really well. You'll also need an inverter that will handle the start-up surge of the compressors/heating elements.

1.5kW of PV panels is a serious weight - I'm sure you can get that on the roof of some vans, but they'll need careful mounting.

With the best will in the world, if you're on the move you're not going to get the best out of your panels - they don't like changes in incident light levels, so you're going to need BIG batteries to overcome the deficit charging situation. From experience I'd suggest at least 400AH if you're are 24V, double that for 12V . That's big and heavy. And you will loose charge, and they'll need charging from a hook-up, and you will need to EQ them all ...

And if you've got a system of that size you'll be spending more time on maintaining and worrying about it all than enjoying life - I know, I get paid to look after off-grid systems for people who don't want the worry having tried it .

I think it's the conclusion the OP has come to, but really - a change in lifestyle expectation is going to be much easier to handle - and hugely cheaper - the system I've outlined runs into thousands ...

PS: In theory, a battery-to-battery charging system would help a lot - we've pulled apart the specs/design on the usual suggested one and I know some of the regulars here use them with great success. I can't offer an opinion though as this is where solar power gets very vehicle/alternator specific and out of my experience and personal knowledge.

Mild Red