Solar Panels

[sgreensides1]

Hi

We are new to motor homing, so would appreciate some help.

 

Our motorhome is in storage, so solar panel(s) to ensure that leisure and vehicle batteries are fully charged when we pick it up seems to be the way to go; but what options / suppliers / sizes / etc.

 

I met an electrician who had fitted his own large panels and his system charged all batteries by 10:00am and then ran the fridge till dusk saving some gas. This seems ideal, but the complexity puts off suppliers.

 

a) one panel set to do all (batteries and fridge) or separate small one for the vehicle and larger one for the leisure

 

b) flexible panels to save weight or rigid?

 

c) display panel or not (interesting when you first fit it, but never gets looked at later)

 

d) poly or mono crystal

 

e) do you go over the top in Summer, because the panels will perform less in the Winter?

 

As you can see, so much to learn, but where to start.

 

All help would be appreciated.

 

Thanks

Steve

[garryg163]

Hi I too am new to the game, I did a little research and I thought I might have a go myself. As our MH is 10 yr old it doesn't have any fancy electronics to be concerned with.

 

I bought a 100W Bosch solar panel from Renytek Solar on Ebay (Went direct and got for £139 delivered) a MPPT 10A controller from Bimble Solar (£72 inc delivery and optional screen) a set of brackets and some stainless screws nuts and aircraft locknuts, from a hardware store (About £10) Some sikaflex grab adhesive £11 off the bay. A cable gland and a couple of 30A in line fuses. (about £235 all in)

 

Being Uber cautious the job took about 5 hrs to complete with care being taken to route the cable through lockers and behind seats to the battery bay under a sofa. The controller was mounted about 600mm away from the battery with a 20A fuse in line on the live side, and the head unit put in a visible spot on the wall. I also put in a fused 12v Car Socket on the load side to charge up devices with the extra power the leisure battery doesn't take for charging.

 

I also purchased a 4W A4 sized top up book style panel for £17 off the bay for the vehicle battery. That kept my vehicle battery topped up for about 6 weeks just leaving it in the windscreen.

 

I am currently in the MH having been on tour for 12 days and batteries have been excellent. The touring has topped up the vehicle battery with the Bosch doing the business running the fridge during the day and lights etc at night. We have only stayed on site for x3 nights so far and all is well (With 5 year + old batteries)

 

All in all a worthwhile exercise for £250 ............ IF you are in to DIY. Hope that helps

[colin]

Have been using Solar for quite a few years now.

Conventionally you would only run fridge off solar if it's a compressor fridge, a three way fridge is not very efficient on 12v, it may be the cost of bigger panels to overcome this might cost more than running on gas.

Using less panels and a set up which charges both batteries will be tidier and possibly less expensive.

weight is not much of an issue for us, on our old T25 van we had a semi-flexible panel which bent to shape of roof and tucked in behind roof mouldings making it more aero efficient, our present van has fixed frame which sticks out into the breeze a bit, I keep meaning to look at the front and rear edges to make them better.

To me it's a fit and forget system so am not that interested in a continuous display.

The panel will need to be big enough to work when you use van, so this will mean it will be oversized in summer if you use van in winter.

[sgreensides1]

Thanks, This helps a lot as I am hoping to do this my self as well.

Really appreciated.

Steve

[steve101]

You need to do some workings out to start with. Take a look at what you are likely to be using and how much it uses. Then look at the size of the leisure batteries and how old they are.

 

In this country you are only likely to get a reduced amount of power from the specifications on the panel stats as they are under ideal lab conditions.

 

The check to see what space you have to mount them and see how many you can fit in.

 

They are good there is no doubt as so many people are going this way now. I have one, it is a 100w semi flexible linked in to a 110ah battery. Depending on weather conditions it will keep the battery running the van without a problem.

[sgreensides1]

Thanks

I was thinking of 150 watt as we like our electrical gadgets and am sure that our consumption will grow.

Steve

[StuartO]

There is a potential downside to choosing larger solar panels than are necessary and 150 watts is maybe quite a lot unless you have multiple and large leisure batteries.

 

The potential problem is that some solar panel regulators, perhaps most of them, are less sophisticated than other leisure battery/engine battery maintenance chargers, so they deliver a voltage of 14.0 or even 14.3 volts to a fully charged 12 volt battery bank, rather than dropping back (as the ideal charger does once the battery is fully charged) to 13.6 volts or so. Delivering 14.3 volts to the battery on a sustained basis could cause gassing off and loss of electrolyte with liquid electrolyte batteries. Solar panels won't apply 14.3 volts continuously of course because they only generate during daylight hours, but they might do it for long enough overall to over-charge a liquid-electrolyte battery such as the engine starter battery.

 

(Gel batteries can cope with a longer period of end-of-charge 14.3 volts so they are probably at much less risk of being over-charged by a solar panel.)

 

So choosing how many watts of panel to fit should be done with reference to the battery types and capacities which they will be maintaining in storage as well as the ampere hours of 12 volt services you plan to use each day when the MH is occupied. You can always add extra panels to increase the charging capacity if it turns out to be insufficient but you can't chop bits off if you fit too much in one panel.

[Mahonia]

I fitted an 80 watt solar panel on my static caravan 3 years ago and it has been fantastic for keeping my 85 ah battery charged. This is especially useful in the winter months when the site is closed but the solar panel keeps my battery topped up. When using caravan I don't have many gadgets, I use electricity mainly for lights and for charging mobile phone, iPad etc. However, recently the lights in my caravan have started to shut off after a few hours usage, indicating that the battery is running low. I believe there is an automatic cut off in the controller that prevents the battery discharging below a safe level.

 

I suspect that my battery needs replacing so I'm thinking of upgrading to a larger capacity battery, perhaps 110 ah. Could anyone advise what is the best type of battery to go for, and whether it us possible to use 2 batteries together to store more power?

 

Any help much appreciated, thank you.

I should add that I don't have an inventor and only use 12 V appliances and lights.

 

 

 

 

[747]

It might help if you tell us which make and model of motorhome you have.

 

This could influence the advise you get as European makes are different in some respects to British vans.

[StuartO]

Mahonia - 2014-10-09 10:56 PM

 

I fitted an 80 watt solar panel on my static caravan 3 years ago and it has been fantastic for keeping my 85 ah battery charged. This is especially useful in the winter months when the site is closed but the solar panel keeps my battery topped up. When using caravan I don't have many gadgets, I use electricity mainly for lights and for charging mobile phone, iPad etc. However, recently the lights in my caravan have started to shut off after a few hours usage, indicating that the battery is running low. I believe there is an automatic cut off in the controller that prevents the battery discharging below a safe level.

 

I suspect that my battery needs replacing so I'm thinking of upgrading to a larger capacity battery, perhaps 110 ah. Could anyone advise what is the best type of battery to go for, and whether it us possible to use 2 batteries together to store more power?

 

Any help much appreciated, thank you.

I should add that I don't have an inventor and only use 12 V appliances and lights.

 

It doesn't sound like additional or bigger leisure batteries would help and it also sounds like your panel/regulator combination is OK, so you probably just need a decent replacement battery. Was the leisure battery new 3 years ago and is it a proper leisure battery? If yes you are unlucky if it has failed and maybe it should still be guaranteed?

 

You can test the battery by taking it home, charging it fully on the bench, then leave it for 24 hours and check the voltage. If it is less that 12.6 your battery is failing. Use a 12v lamp to discharge it and recharge a couple of times and maybe use a clever charger to try to recondition it (lie a CTEK) but if it turns out to be knackered, replace with a decent 85 AH leisure battery. The Bosch S5 series are new technology, potemtially better than a gel battery, and have a 5 year waranty, so i would go for one of those.