Hi I have a caravan and have placed 2 160w solar panels on the roof ,each panel has a separate solar controller. The 1st is wired into the controller then wired to 2, 95ah gel batteries and the load (from the controller) is wired to a panel with 2 female cigarette lighters and some usb plugs. The second is wired into another control panel that is also wired to 2, 95ah batteries and the load from the controller goes the the caravan which runs lights the water pump and keeps the ignition for the gas fridge going. I have wired the batteries I think in parallel keeping them 12v. My first question is , I have not fused this system can anyone tell me what fuse's I should use and where do I wire them. My second question is I have 6 second hand 95ah batteries (all the same make),I have seen you can buy second hand solar panels 300w for a reasonable price. I am thinking of buying 2 and using them with a stand outside to heat water with a DC water heater. But with 600w what size element will I need and can I get away with a normal solar controller when I wire it the the battery bank of 6. Sorry for the long post. I would really appreciate any help, amps, watts, volts really cook my head ( the reason for the 6 batteries is I'm thinking of running a 500w oil heater through the night. The panels I'm thinking of plugging direct to the DC water heater (when I need it) and then replugging them to the controller panel when I want to charge the 6 batteries ) thanks again 😁 and I know I sound like a complete idiot who is trying to burn my caravan down.
All sounds very complicated to me! Going off grid in a caravan in winter isnt that common - I suspect most of us would just use the EHU on site.
And welcome to UKCS, herny123.
i have just made my small caravan off grid capable..
300 watts of flexible panels on the roof..
one 20 amp mppt charge controller..
one 1000 watt inverter..
two 100 ah lithium batteries
one DC to DC 20 amp battery charger..
it has three charging methods.. shore power hook up.. solar power about 15 amps if its sunny.. plus a controlled 20 amps from the tow vehicle alternator if required..
total cost about 1600 quid.. the two lithium batteries being the main cost..
ps.. this off grid thing isnt just about real off grid.. not being totally dependent on a mains power hook does open up many opportunities that would otherwise not be there..
As another ex-boat owner, shore power is a term I often use too.
One thing that I always remember from my river-boating days is "never use battery-electricity for anything with a heating element". The power consumption from batteries is way too much. Gas is much easier and much more economical in a caravan, or diesel heating in a boat. Batteries are very heavy and very inefficient for providing heating for more than a few minutes at a time. 500 watts continuous load overnight would need a massive bank of batteries, probably far more than any caravan could reasonably be expected to carry.
Six lead acid batteries on their own would probably be far too heavy for anything other than the biggest of caravans. They on their own would probably exceed the loading limit of the average sized caravan, and they probably wouldn't be enough to run a 500 watt heater all night anyway.
my pair of lithium batteries would provide a 500 watt load for near five hours but then they would all need charging back up again ready for the next nights session.. this would need a 1000 watts of solar panels even in the summer time..
maybe the op has a static caravan.. battery weight would not be so much of a problem then.. but weight is a major problem with a touring van..
motor homes have the edge here.. they can carry more weight..
basically the op is way over optimistic as regards what can be done with solar power.. in the winter its pretty useless..
Quote: Originally posted by Fiona W on 18/1/2021
All sounds very complicated to me! Going off grid in a caravan in winter isnt that common - I suspect most of us would just use the EHU on site.
And welcome to UKCS, herny123.
That presumes that this person uses sites and doesn't wild camp, as many do.
(My daughter included)
The set up they've got sounds quite typical of what you find on many narrow boats.
Quote: Originally posted by trog100 on 18/1/2021
maybe the op has a static caravan.. battery weight would not be so much of a problem then.. but weight is a major problem with a touring van..
motor homes have the edge here.. they can carry more weight..
basically the op is way over optimistic as regards what can be done with solar power.. in the winter its pretty useless..
my plans are for summer usage not winter..
trog
Very much doubt it would be a static, as I would imagine that most if not all statics would have mains electricity. I have hired them before and all the ones I have known have had mains.
i was thinking more of an old tourer that no longer goes anywhere..
as you say a static would have mains.. having said that houses can have solar panels on the roof and its also possible to mount them on ground based frames.. the idea being green or to save money on the leccy bill..
Quote: Originally posted by trog100 on 19/1/2021
i was thinking more of an old tourer that no longer goes anywhere..
as you say a static would have mains.. having said that houses can have solar panels on the roof and its also possible to mount them on ground based frames.. the idea being green or to save money on the leccy bill..
Thanks for all your reply's and help. To be honest I pitch my caravan (a hobby 690) it's a seasonal pitch and I know everything I'm trying sounds excessive, but I have taken it on as a bit of a challenge. Gas is a lot simpler answer but with the bit of research I've done I'm curious to see if this is possible. As I said I could spend thousands on lithium batteries and brand new panels but I'm trying to see if this is possible on a budget. With my 4 leisure batteries, panels, wiring and controllers I've probably spent about 800. I've changed all my bulbs I run a 32in TV a laptop a 12v portable fridge (as well as my gas fridge ) and even charge some power tools through a inverter. But the challenges I have is heat. For example the water and a small amount of heating in the end bedroom as I don't like leaving gas running all night. Seeing used 300w panels for 50 on eBay with a couple of cracks in them and the used batteries that all hold a even charge and are the same make I thought it might be worth a go. But I see very different views on it with videos I've seen, some people just wire everything together and hope for the best and seem to get by. Then others spend hundreds of pounds on large solar controllers , battery monitors and various gauge cable and seem to get the same results. I'm trying to get a happy medium, I don't want to spend thousands but if the used batteries I've got failed after 6 months and the used panels gave up the ghost it wouldn't be the end of the world.
so assuming your secondhand panels and batteries are all in good condition.. you would have 600 watts of solar and 600 ah of lead acid battery.
would this run a 500 watt (41 amp) heater.. ??
you cant run lead acid batteries fully flat without destroying them fairly quickly so at most you would have 400 ah of usable power.. this would power your 500 watt heater for 4 hours..
would your 600 watt panels charge up these batteries.. 400 ah would need replacing every day.. on a sunny day your might get 30 amps going into your batteries.. your would need 13 hours of bright sunlight per day to put back that 400 ah into your batteries..
i dont think my figures are far out..
trog
ps.. i havnt missed your idea of running the panels directly into the heater.. the idea might have some merit it also might work.. you would have to try it and see.. it would for sure help your batteries..