Solar Panel

[Paul Gosbee]

Hi All

I am considering getting a solar panel (s) for my Autortrail Dakota SE 2003 vintage. I have just replaced the leisure batteries (100ah lead acid) and have a new vehicle battery. I just want to know what size solar panel would be needed to keep them charged when not on a site with EHU and not driving. We have a small tv which we use occasionally, CH which runs off gas with a 12v fan etc but nothing with a high drain. all halogen 12v lights have been swapped for LEDs. I fitted a new EC328 and matching control panel last January and there is a socket for solar panel input on the power supply unit. As we don't use the roof rack on the moho, I thought it would be the ideal place to have it fitted on to as it would allow for air flow underneath. I suppose there are brackets available to suit? Any advice on suitable wattage welcome plus good, reliable makes, good installers here in Herts etc if I choose not to go the DIY route. Would the charging system be suitable if I replace the batteries for lithium in due course??

Thank you

 

[Guigsy]

What time of year do you want to use it? How many days do you intend to be off-grid and not drive?

 

[Raul]

Go for big 60 cell panels. The more the better. With your existing batteries you can fit as much as 480w easily.

 

[Tombola]

Without getting too deep about the sun in the UK and your power needs, Id ignore a 100 w and go for 200 min or above, esp if you are going to add lithium at a later date.
Long story short, if you had a good sun day, 100w could produce average about 50 ah. Given your 100ah lead battery only has a usable capcity of half that then in theory 200 would more than make up for a "not so sunny uk day" but with a little future proofing built in.
Winter....10% of that if your lucky

Also remember a good MPPT solar charge controller.

 

[Raul]

Without getting too deep about the sun in the UK and your power needs, Id ignore a 100 w and go for 200 min or above, esp if you are going to add lithium at a later date.
Long story short, if you had a good sun day, 100w could produce average about 50 ah. Given your 100ah lead battery only has a usable capcity of half that then in theory 200 would more than make up for a "not so sunny uk day" but with a little future proofing built in.
Winter....10% of that if your lucky

Also remember a good MPPT solar charge controller.

Worth noting that kind performance will only last 1-2 months in midd Sumer when the day is the longest. A 100w will average 20ah if you include the spring and autumn months. Winter is dead allot less in UK.

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[Paul Gosbee]

Thank you all for your advice. It has been very helpful indeed.

 

[Richard n Ann]

Thank you all for your advice. It has been very helpful indeed.

Your usage sounds like ours, we've got a small pure sine wave inverter, 230v 24" TV (that Ann has on half the night while she's asleep ) , 230v fan, 12v ceiling fan, LED lighting, water pump & 2 smartphones.

I fitted a 150w panel and a Votronic Duo 250 mppt controller (which incidentally has lifepo4 setting and also looks after the starter battery)
In summer it's plenty big enough with the 80ah gel battery fully charged by lunchtime, even on cloudy days it finishes charging by mid afternoon, the battery is usually in the region of 12.4v in the morning if the ceiling fan (½ amp) is on all night.

If you plan on winter camping I'd double that capacity though or consider a tilting panel, ours can tilt and the amps can go from 2 to 7 in October

 

[Jev88]

The most you can afford and fit and have payload for. There isn't really a number to aim for? The more the better.

 

[tonka]

Note. The EC328 does have a built in solar regulator BUT it is limited. I think it is 100w but check as I'm a bit out of touch since selling our Autotrail 2 years ago. If you did want to use it then look on the Sargent website ref the connection lead.
My recommendation is an extra battery as that instantly doubles your capacity. Fit as big a panel(s) as your roof or budget will take. A good MPPT dual regulator to feed both the leisure and engine battery.

 

[St3v3]

As said, fit as much as you can. Your heating fan will use more than you think, depending on how lo g you run it for of course.

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[mitzimad]

Were not heavy power users we survived with 180a of battery and the same in panels all the usual plus occasional TV weve gone 6 days off grid in Spanish winter weve now got 110 of lithium but haven't tried that in winter

 

[Paul Gosbee]

All useful info much appreciated. yes the EC328 in built regulator can take up to 120w so an addition controller looks like the way forward.