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Solar Panel 80 or 100 ?


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I am planning on fitting a solar panel to my van but the only place i can fit one is accross /side to side on the roof . I was hoping to get a 100 w but the ones at a reasonable price are rather long 1196 approx so will come close to edge when brackets are fitted.

If i go for an 80w the unit size is better but was wondering ..does size matter !!!!! ?? (lol)

will there be a lot of difference between an 80 or 100 .

Not planning on pulling too much through it (may get a tv in future ) but just dont want to have to go on site .

So pump. lights . heating control? and laptop /phone charging.

Opinions welcome.

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The Poly-crystalline panels tend to be physically larger. The slightly more expensive Mono-crystalline panels are more efficient so tend to be a smaller physical size.


The power of the Panel should be calculated from the power (Ah's) you intend to draw during the season you wish to use the vehicle. Consider that during the in Winter in Scotland you will be lucky to get 4Ah a day from 100watt panel, only just enough to stop the batteries running flat when 'idle'.

If you use it near the Equator in mid Summer you might get nearer to 100Ah a day?

I would suggest that if you intend to holiday in the Northern part of the UK in Winter, a Solar Panel will be of very little value.


So suggest you work out how much power you require to get through a day and calculate the size of the panel you need. Bear in mind that some Halogen light bulbs use so much power that you can almost run 10 LED lights for a single Halogen. Therefore it is worth replacing these, and looking at how you can save electricity in General before you go down the Solar Panel route? A heater blower/Pump can draw significant amps on a cold night.


Once you have the power draw calculated, have a look at the battery bank, does it have that capacity? For example if you calculate that you need 60Ah a day and the Solar Panel has the ability to provide that, will the battery store it? Ideally the battery should not be discharged more than 30% (still 70% 'full') for the greatest life. But in anycase not more than 50% to prevent premature failure of the average battery.


Therefore a 100Ah battery will ideally 'only store' 30Ah per day, so you need to adjust the battery bank accordingly. Little point having a 200watt Solar Panel with a100Ah battery for example, unless you go Skiing in Scotland in December, in which case 400watts might not be enough?


In other words there is a lot to work out to see if you and your unique usage pattern will benefit. Hence we suggest you start by minimising the power consumption and go from there?

Some of the items you list, like Heating, Portable Appliance battery charging, TV (at a later date) are not insignificant power consumers.


More Solar Hints and Tips here : http://www.aandncaravanservices.co.uk/solar-power.php






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Obviously the bigger the better, but in the overall output in a day, not much difference. Solar panels are normally used to charge the leisure battery from which you "pull" your power, so your capacity is dependant on your usage and the size of your battery bank.
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It sounds like you have a smallish MH.  If you only really have room for an 80 watt panel on the roof then settle for that because it will generate quite a lot of what you will need in summer, maybe all of it, and you will also generate from your alternator when you are driving - and you will be able to connect to a mains charger as necessary to recharge.  I have a 7 metre MH and 130 watts of panel and that has kept my two 80AH leisure batteries charged up fairly reliably in summer.  If 80 watts turns out not to be enough you could always deploy a folding portable solar panel too, when you aren't driving.


I wouldn't worry too much about the type of solar panel or regulator.  Just use one leisure battery (as I now do) but as big as you can fit in.  It will probably work out very well.


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Thanks all for the advice .

I have a mwb Timberland Starlight but due to roof lights & status it has limited the space.

I will maybe even try and have a go at doing it myself when i get one !!

Just managed to remove & fit a new shower tray ,moving the drain hole ,drilling a hole in the floor !!

Still got all my fingers intact !

Quite an achievement for a girly with no experience *-)


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