'domestic' solar panel on moho ? any advice please

[MisterB]

ive just bought a second hand (but fully tested) domestic solar panel (235w mono for £60) to fit to our new (to us) motorhome which we collect next week. i am hoping to 'find' a bargain MPPT controller at the Peterborough show.

always happy to consider advice/suggestions on the best way forward - the roof is empty at the moment. we don't spend a lot of time off grid at one location, we tend to drive for at least two or three or hours each day, so will also be looking for a B2B and a vanbitz battery master.

as stated, any advice or suggestions are welcome - even if its not to use the domestic panel !!

 

[Stealaway]

What's the voltage of the domestic panel. Could be too high for some solar controller

 

[cmcardle75]

ive just bought a second hand (but fully tested) domestic solar panel (235w mono for £60) to fit to our new (to us) motorhome which we collect next week. i am hoping to 'find' a bargain MPPT controller at the Peterborough show.

always happy to consider advice/suggestions on the best way forward - the roof is empty at the moment. we don't spend a lot of time off grid at one location, we tend to drive for at least two or three or hours each day, so will also be looking for a B2B and a vanbitz battery master.

as stated, any advice or suggestions are welcome - even if its not to use the domestic panel !!

It'll be fine on MPPT, but don't try with a PWM, unless open circuit voltage is around 20V. To be sure, post the actual specs. For the MPPT to work, the nominal voltage needs to be significantly above 12V, but less than the published max voltage of the MPPT controller. I'd be very surprised if it wasn't.

Given you drive a lot, the B2B will give you far more charging in general and I'd concentrate your budget in that direction. Buy chargers that are Lithium compatible, so you can upgrade your battery at your leisure in the future.

 

[MisterB]

It'll be fine on MPPT, but don't try with a PWM, unless open circuit voltage is around 20V. To be sure, post the actual specs. For the MPPT to work, the nominal voltage needs to be significantly above 12V, but less than the published max voltage of the MPPT controller. I'd be very surprised if it wasn't.

Given you drive a lot, the B2B will give you far more charging in general and I'd concentrate your budget in that direction. Buy chargers that are Lithium compatible, so you can upgrade your battery at your leisure in the future.

when i collected yesterday evening, around 6.30 it was showing over 19 volts if that helps ? i will photo and add the label that is on the panel tomorrow

i will prob be adding a second leisure battery aswell at some point !

 

[cmcardle75]

when i collected yesterday evening, around 6.30 it was showing over 19 volts if that helps ? i will photo and add the label that is on the panel tomorrow

i will prob be adding a second leisure battery aswell at some point !

Yes, sounds emminently compatible with any MPPT charger commonly available. Would probably work with PWM as well (at the cost of 15-30% reduction in real world output). Again, make sure it is Lithium compatible. If you don't buy one now, you probably will in a year or two.

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[MisterB]

Yes, sounds emminently compatible with any MPPT charger commonly available. Would probably work with PWM as well (at the cost of 15-30% reduction in real world output). Again, make sure it is Lithium compatible. If you don't buy one now, you probably will in a year or two.

i am looking at a 20A MPPT - or is that overkill? i am unlikely to be adding any more solar, as i will be fitting B2B and BM, so dont really need to add in any additional capacity

just did a google and it says 20 amp is ok for 240watts on a 12v system, so it looks like 20A is ideal - or will it be working flat out (and so a 30A would be better?)

 

[TerryL]

In theory, yes a 20amp MPPT should be fine, given that your solar panel is rated as 235W max output (20a x 12v = 240w)

But personally, for the small difference in cost I'd go for the 30a to give a little "wiggle room".

 

[MisterB]

In theory, yes a 20amp MPPT should be fine, given that your solar panel is rated as 235W max output (20a x 12v = 240w)

But personally, for the small difference in cost I'd go for the 30a to give a little "wiggle room".

does it need wriggle room?

as i dont intend increasing the solar panel, is there any point - bearing in mind a 30A would still only give me 360W of solar?

 

[Raul]

A 20a victron controller will be a match made in heaven. The panel is a 30vmp and 37voc open circuit. The victron mppt will handle that and and more; the 20a controller can take up to 290w panel, and 100v open circuit.

 

[cmcardle75]

does it need wriggle room?

as i dont intend increasing the solar panel, is there any point - bearing in mind a 30A would still only give me 360W of solar?

Victron MPPT just throws away any electricity above the rating. It is not damaged by it.

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