Small UV Panel & Wind Charger Installation for caravan,

[SteveNotlob]

Hello all.
I will be siting my caravan on a seasonal pitch from next March.
The caravan is mostly 12v DC (lights, fan, toilet pump, water taps, etc) with a few 240v AC sockets (TV, Heater, Microwave).
I would like to run all my 12v from a solar panel array (around 200 watts total) and a small Rutland wind charger combination.
Firstly, is this easy to do on the 12v side? I have seen several cheap (under £100) combination controllers for wind and solar, are they good? What sort of battery capacity would I require?
Secondly, Is it feasible to at least run the TV (about 3 hours per evening) via an inverter with this combo of solar / wind?
I want to do my (little) bit for the environment (and also save money on using site electrics to run everything including battery charger for 12v!) but it would be pointless if the upfront cost is out of financial reach.
I already have the Rutland wind charger (it's the 910 furlmatic) and I can source 2nd hand solar panels cheap. It is the controller side that worries me!
Thanks for any advice.
Stephen

[RustyNuts]

There is a rough process for this. Work out what your load is (in watts generally) and for how long per day you are going to require that consumption. When you have that figure you can then work out the amount of battery capacity you will require and how much solar power you will require to replenish the battery loss for the following day. This is a simplification as the amount of available sunlight and for how long per day you will need depends on not only the available sunlight, the position of your solar panels, their efficiency and how efficient systems like inverters are as well as the true consumption of the devices that need powering. There is also the type of batteries you invest in, how efficient they are in respect of the level of discharge that they can provide in real terms. Lithium Ion batteries can deal with much deeper levels of discharge than lead acid and some lead acid batteries will deal better with lower level of discharge as in AGM versus the standard deep cycle leisure batteries that many people install in to off grid systems like caravans and camper vans which only really provide 50% of the amp hours they are rated at before you may start to damage the batteries (higher discharge for AGMs which may allow 70% discharge with similar risks to long term damage meaning they come much more highly recommended by me). This is an important consideration as if you decide you will use 80amp hours of battery per day and you therefore decided on a 105ah battery, you will only really get around 50ah out of it before you start to piss the battery off.

Throw in diversity where you may run certain items for longer on some days than others and maybe bringing in a new electrical item to the caravan and it becomes a potential minefield designing a system to fit your needs. Also the available space for things like inverters, solar charge controllers and batteries and you have a lot to think about. On top of that, your suggestion of running an electric heater from a battery based inverter is NOT to be recommended in your situation so you may do better to consider a diesel heater with a separate diesel supply which can be had for £100. A 1000watt heater running off an inverter will use around 4.5amps at 240vac or nearly 80amps at 12.8vdc so even if you had a 200ah AGM battery, it would drain it way too quickly (and dangerously)  in  not much over an hour. Avoid this idea.

On a positive vibe, you can buy a simple electricity usage monitor for under £20 that will show you how much you are using from the hookup (look them up on Amazon/Ebay etc..) to ascertain how much your consumption is over a normal day (presuming that your 12v stuff is already being transformed from the 240ac mains supply) which will give you an idea of what sort of battery system you will require and an idea of what solar panel array and wind power you'll require to recharge your batteries for the following 24hrs, replacing the hookup you seem to want to get away from.

Remember also that DC to AC inverters have a manufacturers efficiency rating that (if to be believed) will require more energy to run than simply using 12vdc appliances such as a 12vdc television or monitor. The larger the inverter running a much lower load than it is capable of supplying at the top of it's game will give a much poorer efficiency rating so avoid trying to buy the 2000/3000watt inverter when you are never going to demand more than a couple of hundred watts from it. People are much better served by an inverter closer to their true regular requirements, oh and make sure that it is a true sign wave inverter which are more expensive (but not really expensive) as many devices do not like a choppy AC wave.

If I was you and on a budget, I would look at AGM batteries that have a lower 'safe' discharge rating than basic deep cycle leisure batteries (from Halfords/GoOutdoors say). Something like the EpEver MPPT solar charge controllers for your solar array. Ideally, if you have the space, consider something like the EpEver UP1000-M3212 or similar that will deal with solar arrays up to just under 400watts for battery charging, built in sine wave inversion and even accept the hook up to not only charge the batteries when the sun isn't working out for you, but will offer a through to the inverter to power you 240ac kit. But, do you have the space for that and a decent capacity battery/batteries? Only you can answer that...

I have a mixture of Victron and EpEver equipment. Both of which have served me very well though the Victron offerings are usually much more expensive. Sometimes for good reason. Decent quality solar panels aren't that expensive any more but the more you can afford for the space you have to stick them is an important consideration. In my view, you can never have to many in the Uk. Especially up north  ???