Bespoke off-grid power

acecard

Member
Joined
Sep 8, 2019
Hi all,

Really giving some serious thought to my electrical setup now before I start constructing any of the truck structure. Our aim is to be as sustainable as possible, but we do want to include a back-up LPG generator that will provide charge to the batteries on days where the renewables aren't quite performing! I have approached a few companies that deal in design of these types of systems, but the prices are so high that I think I might be better off sourcing and putting everything myself. Any help on the following much appreciated!

How might I go about putting together a system with the following elements?:
  1. Solar and wind charger input
  2. Back-up LPG generator that acts as a third input to charge the batteries when turned on (not sure if this is best, or whether the generator should simply power an inverter directly - maybe the option to switch over to have both options??!!)
  3. A set of 12V circuits to run lights, 12V plugs (inc. USB plugs), water pump, water tank level sensors and water heater
  4. An inverter that runs a set of 240V plugs
  5. The ability to connect to a mains hook up and choose to run my 240V plugs from this, or the inverter with a switch-over
  6. A trickle charge from the renewables to the truck battery in case of a long stand in one spot
  7. A charge generated from the alternator to charge the batteries when the engine is running.
I've scouted the net and can't seem to find anything that quite fits the bill.........perhaps what I want can't be done?! Also, there is such a huge variation in price with some of these products; is there much to be lost be going for cheaper non-branded components? e.g. on Amazon I can get a basic 1.4kW solar and wind kit for £1400. But then you look on specific sites that design these off-grid systems and your paying nearly that JUST for the wind charger!

Thanks
AC
 

BigStevie

Active Member
Joined
May 17, 2017
Location
Highlands
Hmm.... first, work out how much energy you need. This of course depends on what energy using devices you have. LED lighting consumes next to nothing, on the other hand if you’re having a tv, they’re energy hungry.
So, work out how much power you need, then design your system to suite.

There are plenty of split chargers/inverters/solar controllers etc etc. You can spend a little or a lot, it’s really up to your budget.
My present build uses a cheap 200w solar kit, a pair of cheap-ish batteries, a good quality Durite split charger (which allows the solar panels to charge the vehicle battery), cheap Chinese lights/sockets/fuse box. And all seems to be working well.
I have a stand alone mains hook up, just to a consumer unit and then a few sockets, this is as we’re intending to use the van wild.

I would add, that unless you have the right tools, have your battery cables made up by a professional. Also, basic stuff, make sure all circuits are fused and everything’s properly earthed (I tend to use earth cables returned to a central point, helps if you have faults).

There’s plenty of info on the site if you have a dig back, or just ask!

Good luck!

Stevie
 

shawn&emma

Member
Joined
Jun 28, 2018
Location
Portugal
We had a wind turbine on our van and to be honest unless you are somewhere exposed, as we were then on the west coast of Scotland the power you get from the turbine is not worth it. The only benefit was that during the night the turbine did add a little to the batteries but where I had it fitted I had noise/vibration coming down through to the van so you couldn't sleep properly.

Ours was on a 3 meter folding pole on the roof.

I really wanted it to work but extra solar is probably the way to go in reality.

Shawn
 

acecard

Member
Joined
Sep 8, 2019
It would help if you told us what equipment you plan to run off your power supply.
Also is the truck 12 v or 24 v?
David
Over the last few days I have simplified our system a lot. The biggest things here include deciding not to have a dryer (didn't realise the MASSIVE draw of this thing!) and also not having the unit coupled to the truck electrics, (ideally I want the box completely stand-alone so that it can be easily moved onto another truck chassis if needed), and also not bothering with a EHU (if I spec out the right solar system and couple that with a generator instead then there is not real point in one of these). So, the system will be 12V only, and in terms of 240V, I will now only be concerned with a washing machine, fridge, Nurtibullet and laptop charger! I was considering a gas fridge, but the larger ones seem very expensive in comparison, so I think it is best to stick with 240V and an A+ rated fridge with an annual energy consumption of 116KWh.
 

acecard

Member
Joined
Sep 8, 2019
Hmm.... first, work out how much energy you need. This of course depends on what energy using devices you have. LED lighting consumes next to nothing, on the other hand if you’re having a tv, they’re energy hungry.
So, work out how much power you need, then design your system to suite.

There are plenty of split chargers/inverters/solar controllers etc etc. You can spend a little or a lot, it’s really up to your budget.
My present build uses a cheap 200w solar kit, a pair of cheap-ish batteries, a good quality Durite split charger (which allows the solar panels to charge the vehicle battery), cheap Chinese lights/sockets/fuse box. And all seems to be working well.
I have a stand alone mains hook up, just to a consumer unit and then a few sockets, this is as we’re intending to use the van wild.

I would add, that unless you have the right tools, have your battery cables made up by a professional. Also, basic stuff, make sure all circuits are fused and everything’s properly earthed (I tend to use earth cables returned to a central point, helps if you have faults).

There’s plenty of info on the site if you have a dig back, or just ask!

Good luck!

Stevie
Thanks for the pointers Stevie,

No TV to worry about for us! We only ever watch streaming stuff anyway so can easily do that from a tablet/laptop.

Glad to hear you recommending cheaper stuff.......I was worried that I was going to get a whole bunch of replies saying that the cheaper stuff was junk! I guess to some extend you get what you pay for, but I believe to a greater extent that the only thing you get extra is a brand and most of the stuff roles off the same conveyor belt anyway, doesn't it?!

Could you perhaps post me a link to the 12V lights and switches you used?

Thanks!
 

acecard

Member
Joined
Sep 8, 2019
We had a wind turbine on our van and to be honest unless you are somewhere exposed, as we were then on the west coast of Scotland the power you get from the turbine is not worth it. The only benefit was that during the night the turbine did add a little to the batteries but where I had it fitted I had noise/vibration coming down through to the van so you couldn't sleep properly.

Ours was on a 3 meter folding pole on the roof.

I really wanted it to work but extra solar is probably the way to go in reality.

Shawn
Thanks for the heads up! I like the idea as I thought that most likely, if the solar is under-performing due to weather then the wind turbine should at least be churning out! Will ditch that idea now and just perhaps run and overspec'ed solar system to compensate for the cloudier days.

One thing that I just found out about that concerns me a little is the issue of shade and how it affects panels. I hear wiring in parallel helps this, but this reduces the output voltage of the panels compared to running in series. So in light of this (pun intended!) I think I will have to overspec quite a lot.
 

david.c.hall

Active Member
Joined
May 16, 2016
Location
Irnham, South Lincolnshire
So, I guess, your biggest power user is the washing machine
With an A+++ machine you will use about 150 Ah of battery and 50 litres of water !
I would think that the most practical way is to run the washer direct off the Generator.
You will also have to factor in the water storage for both fresh and grey water for it.
Personally I have always gone for a trip to the launderette!
David
 

acecard

Member
Joined
Sep 8, 2019
Yeah, the laundrette was certainly a thought, but we wanted the option to be able to wash on-board. We were planning to utilise things like the 15min quick wash cycle more often than not, hoping to use less energy this way. But yes, you are right the running it off the gennie might be a better solution, but if we have both options, then I guess we can see if we can manage with the solar alone.
 

BigStevie

Active Member
Joined
May 17, 2017
Location
Highlands
Washing machines eat energy by heating water and prolonged spinning, on top of that there’s the weight that’s constantly costing you fuel and performance.
I’d be tempted to do some sums, looks like a heck of a lot of weight and energy to perform what is a very basic task really.
As David mentioned above, then there’s the water aspect of using a washing machine. I’d be having a real good think about this one before committing.

Lights and switches. Just trawl fleabay for used caravan lighting. New LED strip lights are all over the net for a couple of quid each. A scrap caravan can provide a lot of good parts. On a previous build I used an old caravan for its lightweight ply, bathroom, cooker, gas system, electrical bits, gas bottle clamps etc etc etc. Turned out to be an invaluable source or odds and sods.

Stevie
 

acecard

Member
Joined
Sep 8, 2019
Ok so I've just come to realise that you can get a combined inverter/charger unit. However I can't seem to find one with a high enough wattage for the system I'm trying to spec out for a decent price. Can anyone recommend one? Or is it cheaper to get a separate inverter and separate charger unit?

Thanks
 

BigStevie

Active Member
Joined
May 17, 2017
Location
Highlands
It’s been a few years since I was involved with helping a mate set up a system. Personally, I’d be going for separate units, makes problems and upgrading easier and gives you the ability to get what you need.

Stevie
 

acecard

Member
Joined
Sep 8, 2019
It’s been a few years since I was involved with helping a mate set up a system. Personally, I’d be going for separate units, makes problems and upgrading easier and gives you the ability to get what you need.

Stevie
Thanks Stevie! Can you set up these separate configurations to run in the same fashion as the combined units i.e. that when on EHU (or gennie in my case), it auto detects and then runs all plugs from that source as opposed to the 12V inverter?
 

acecard

Member
Joined
Sep 8, 2019
Thanks, will do the rest of the digging now that I know what I am roughly looking for and see what comes up!!!
 
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