Building the solar panel charging system... what to get?

[leosaphira]

Have sold a few bits and bobs on eBay so I have some ££ in my paypal account so now would be a great time to get the bits in to do my solar panel install. I would like to ask the experts here on what I need based on my use.

Ideally I would like to be doing this as a "full time" setup.. as who knows what may happen in the future.

I currently have in the bus the following devices that uses the 12v supply

• Eberspacher Night heater (for the winter months)
• 12v mini cooler (for summer months for milk etc),
• 3x 12v cig sockets to charge things up like my laptop (40w) - mobile phone (via USB charge dock) and LED light Bar for night use - 2-3 hours for laptop and same for phone (these are the main ones)

As my bus is a 24v I will need to be installing a Durite 24v to 12v split relay unit from the cranking batteries in case of poor weather etc

I would be looking to put in 2x 100/110amp leisure batteries in (got the boxes already under the bench seats)
Would These be okay?
12V 100AH NUMAX LV26MF Leisure Battery Caravan Motorhome Marine Boat Motor mover | eBay

What sort of solar panel should I be looking to fit into this system based on my useage? - 2x 80w ones?
80W Watts Monocrystalline Solar PV Panel 12v 24v Battery Charge 80 W Caravan MCS | eBay

But I am not sure about the solar controller... can anyone recommend one? (ideally one I can get via eBay)

Many Thanks

 

[hextal]

Is it worth having a sit down with a calculator and totting up your amp-hour usage for an average 24hr period, just to get a more detailed handle on it?

Mine is under construction but I've installed 2x100w panels and am planning 2 to 3 110ah batteries.

Remember that the batteries shouldn't be discharged beyond 50% if you want to avoid long term damage. So you've got 110ah to play with. a 100w panel will give you a max of 5ah ish for a length of time dependant on the time of year.

Mppt type controllers are better as they are more efficient but the cost a fair bit more. Just get one that can handle the panel output with a bit to spare.

 

[maingate]

The Numax batteries you mention are similar to the 110 Ah ones I have had in my van for over 2 years now. I have had no problems with them.

 

[big tom]

Solar Panels

I installed 2x 80w solar panels £80 each ebay, together with 15amp controller £80 these seemed over the top for my needs during spring summer, I am sure others here will give you more info for winter use.Have a read at this before purchasing batteries Sterling Power Products: What is the best battery to use for an auxiliary charging system? I think the mini cooler will have the larger drag on your batteries,The best advice I can give is to have a large enough controler so you can add additional panels if need be without changing the controller.

 

[wildman]

in the winter 80W panels have and output of less than half an amp per hour (more often a quarter of an amp), so you can forget your cooler then. Not sure how much power the eberspatcher will draw. If you are fulltimimg you will need at least 3 batteries and possibly 4. I have 4 x 110 amp/hr batteries and 2 x 80W solars, not enough in the winter for me. I am about to add a third solar and a wind generator for the winter period, it will charge 24hrs a day as long as its windy. Of course if you push off to Spain or Portugal for the winter you will manage.

 

[leosaphira]

in the winter 80W panels have and output of less than half an amp per hour (more often a quarter of an amp), so you can forget your cooler then. Not sure how much power the eberspatcher will draw. If you are fulltimimg you will need at least 3 batteries and possibly 4. I have 4 x 110 amp/hr batteries and 2 x 80W solars, not enough in the winter for me. I am about to add a third solar and a wind generator for the winter period, it will charge 24hrs a day as long as its windy. Of course if you push off to Spain or Portugal for the winter you will manage.

Thanks ... yes in the winter months the cooler won't need to be used as the step will be cold enough for the milk

I believe the heater uses 50w an hour or so (hence I need to get it rigged up with the campers main electric system so its charging on the move for the winter months)

Am looking to start off with 2 batteries and 2 panels to build the system (as not full timing "yet") but leave the space to upgrade as the time comes.

But in all, its mainly to have the led light on, power my netbook (which I can charge at work in the truck there as am a trucker for them) and mobile phone. Don't have any other wizz bang gizmo's as I would like to lead a simpler lifestyle (which may all change when the girlfriend joins me !)

 

[oldpolicehouse]

Hello
I recently fitted 2x80 watt panel about £80 each from Belgium. Came well packed in 2 days. The same seller TRAD4U eu has 100W panels on for £86
I used this controller.
20A 12/24V MPPT solar charge controller 20A MPPT solar regulator for RV Boat | eBay
Seems well made, performs well and the digital display gives you loads of information. It's a bit pricey and it took about 2 weeks to arrive but again it was well packed and I got away without paying any import duty etc.

Hope this is useful.

Blue Skies

 

[GRWXJR]

Using less is better than more storage

The problem we find in work with off-grid installations (which like this are 'limited power' systems - just bigger and we convert the stored DC back into AC) is that when you change one item, you affect something else. I think this is a similar situation?

If you upsize the battery storage, then you need to upsize the charging system to be able to look after it properly (so in this case the charge alternator run off the engine might not be strong enough to cope with the engine starting battery AND 2 or 3 leisure batteries for example. In Off-Grid domestic systems we found that its always a balancing act of Generator output, Charger Output, Battery Storage and power consumption and peaks. Move too far away from the balance with any one aspect and you have to change them all to restore functionality and efficiency).

Not my area I'll admit, but theoretically (As others are saying about solar panels / turbines) - you need enough (maybe 3 or 4 times in the UK what you think you might need to support the system due to turbines efficiency on a typical UK site being about 25% I believe, and our poor sunlight) or an engine-driven generator to be able to replenish you electrical storage in a reasonable period of time without having to run the van engine.

Hence using less has got to be better than a cascade effect of having to uprate one thing as you uprate something else?

As another poster pointed out - you only get to play with perhaps 50% (or 60% tops) of a battery's rated storage as well - so 2 x 110AH units connected to give you 220AH will only yield 110 - 130AH. That's only 1.56kW tops of available stored energy from 2 fully charged, brand-new and healthy 110AH batteries.
When a modern household electric kettle uses 3kW to boil water - it puts things in perspective and clearly demonstrates why you need to use as little electrical energy as possible or you'll run out fast!

BTW - I read recently that an Eberspacher Diesel Heater takes something like 20A to ignite, and about 1A to run. So better to leave it on once started then to switch it on and off, as you'll use a lot less energy out of your battery storage.

I hope my waffle proves to be accurate and not too boring!