2nd Solar Panel

Shaun944t

Full Member

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7
Hi all,
I have a bessecarr E495 with the leisure battery in the centre of the floor . I have added a 100w solar panel and connected to the existing battery via a controller.
I have since added a second 110ah battery under the seat and run a positive and negative cable to the original battery.
Q: is this the correct way?
I would like to add a second 100w panel, what would be the best/correct way to do this?
Grateful for any advice,
Shaun944t
 

Hungryhomer

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29

Shaun944t

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7
Many thanks for the info hungryhomer I can see that I need to connect the batteries differently and may need a bigger amp controller as opposed to a second one!
 

trevskoda

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1,659
Many thanks for the info hungryhomer I can see that I need to connect the batteries differently and may need a bigger amp controller as opposed to a second one!
Being honest the first way will work ok,mine are done that way,but the second is the correct and best but almost nothing in it esp if batts are more than a few mths old.
 

Hungryhomer

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29
Many thanks for the info hungryhomer I can see that I need to connect the batteries differently and may need a bigger amp controller as opposed to a second one!
Yeah we can add all the panels and batteries we like but if the cables and equipment moving that current cant take it, its pointless. And can be dangerous in some aspects.
Good luck, pose any questions here or on wildcamping.co.uk and you'll get good responses.
 

Markd

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763
Arguably it would be better to get a controller with higher voltage capacity so you can series link the panels and reduce voltage losses from roof and that way boost charge current.
 

nabsim

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2,334
Arguably it would be better to get a controller with higher voltage capacity so you can series link the panels and reduce voltage losses from roof and that way boost charge current.
At the cost of losing a lot more if shading. I think if you have a lot of panels a combo of series and parallel is okay but just having two I stuck with parallel. Same as everything else though, swings and roundabouts with everything 👍
 

wildebus

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It is true that a Series Configuration means less voltage drop and so a more efficient system but ..... TBH, the difference in performance for the size of arrays on the roof of a motorhome is so slight you would be hard pushed to tell and a couple of extra minutes of cloud cover in a day is more likely to have a greater impact.
The main reason to go for Series over Parallel is if the cabling that is installed would not cope with the greater current.
 

wildebus

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2,677
Being honest the first way will work ok,mine are done that way,but the second is the correct and best but almost nothing in it esp if batts are more than a few mths old.
more than you think, Trev. I did a drain test on the two difference configurations (using the same two batteries), seeing how long a Waeco CRX-50 would run for before the Battery Bank dropped to 12.0V (so around 50% SOC typically). When the two batteries were cabled up in the optimised way, I got an extra 1/2 day of the Fridge running.
I didn't expect the difference to be that much, but there you go ....
 

Markd

Full Member

Messages
763
@wildebus said - The main reason to go for Series over Parallel is if the cabling that is installed would not cope with the greater current.

That's what I meant - going series on the roof obviates the need to rewire down to the controller thereby allowing a simple piggyback connection.
The current down will remain the same rather than doubling and whatever voltage drop there was will remain the same rather than double.
This gives the controller a better chance to do the business.
Having said that shading becomes more critical.
Phil's video of a single hand sized shadow dropping the array's output by 25% was a bit off-putting.
 
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Mark135

Full Member

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42
If connecting in series, make sure that the max power current is the same for both panels (or very similar) in your panels or else the one with the lowest current will limit your total power. If connecting in parallel, make sure the peak power voltage is the same for similar reasons. If you use identical panels there is no issue whichever way you connect them.
I am adding an extra 160w panel and a bigger controller. The existing panel is a 100w Truma that came as OEM but I am not paying their silly prices for another one. The new 160w panel has an 18.1V peak power voltage and the Truma is 18.5V. I will connect them in parallel so the peak voltage will be limited to 18.1V. I will loose a tiny amount of power from the Truma but it will be negligable
 

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