Fitting another solar panel.

Submitted: Saturday, Feb 15, 2014 at 15:56
ThreadID: 106251 Views:2089 Replies:5 FollowUps:4
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Hi all. I have a van with a 130watt panel fitted to roof of van running to a 100A battery in van. Can I fit a Anderson plug to battery and hook up a portable 80watt panel and use both panels at the same time. Both panels will be running through their own regulators. Thanking you advance.
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Reply By: Shaker - Saturday, Feb 15, 2014 at 16:13

Saturday, Feb 15, 2014 at 16:13
People here told me yes, industry experts told me no.
I went with the expert advice & run both through a single regulator.

AnswerID: 526518

Reply By: Dennis Ellery - Saturday, Feb 15, 2014 at 17:02

Saturday, Feb 15, 2014 at 17:02
In some cases running two charging devices such as solar panel controllers in parallel will give you less than optimum results – particularly as the battery approaches full charge. They can get confused when sensing the other charger’s voltage as if it were the battery’s and give a false impression of its state of charge. In some cases the effect may be minor and you may gain a decent improvement in the charge rate when the battery is heavily discharged or the panel output is low.
AnswerID: 526519

Reply By: Member - evaredy - Saturday, Feb 15, 2014 at 18:52

Saturday, Feb 15, 2014 at 18:52
I have been told by both Redarc and Ctek, you have to disconnect the other panels regulator.
I f you have a DC-DC charger fitted you won't need the panel regulator anyway.

I have a camper trailer that has 2x 65w tilting panels mounted on the roof, I also have a Redarc BMS Battery Management System in the CT along with a 120ah battery.
Then I have a 120ah in the tub of my Dmax, this is controlled by another Redarc BCDC1240 charger.

I also wanted to be able to hook up my 120W folding panels to either the CT's system or the ute.

Because I am no good with electrica'ls, I had a sparky put and Anderson Plug on the rear of the ute that I could just plug into to help charge the ute battery. I did the same with the CT, just had an Anderson fitted under the CT at the front and wired into the system.

They also fitted Anderson plugs on the 120W panel, so when I want to run it through the trailer or ute I just unplug the regulator and when I need to run the panels on their own I just plug the regulator back in.
AnswerID: 526523

Follow Up By: Member - John and Val - Sunday, Feb 16, 2014 at 08:12

Sunday, Feb 16, 2014 at 08:12
"I have been told by both Redarc and Ctek, you have to disconnect the other panels regulator.
I f you have a DC-DC charger fitted you won't need the panel regulator anyway."

If you have one of the dc-dc chargers that includes a solar controller such as some from Redarc and Ctek, then you would preferably connect all panels directly to its solar input and bypass any other controllers. The dc-dc charger is only concerned with what's coming from the alternator though - with most dc-dc chargers (those lacking the solar function) you DO need a solar regulator.

As Dennis has explained, it's better to use a single solar regulator rather than one for each panel.

Your Redarc BCDC1240 and Redarc BMS do include MPPT solar regulators so hopefully your sparky has connected your extra anderson plugs to their solar inputs. If that's the case, you should bypass the on-panel controller. If however he's simply connected the plugs directly to the batteries you will need to retain the on-panel controller.

Down below, dieseltojo says he's been informed that additional panels should be of similar size to the original, otherwise " the lower level panel will reduce the effectiveness of the larger panel to that of the smaller one". He has been misinformed - this is not so. Perhaps the salesman was confused by the effects Dennis referred to, or maybe he was just confused or prone to inventing new facts as salesmen tend to do!

Cheers

John

J and V
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Follow Up By: Member - evaredy - Sunday, Feb 16, 2014 at 12:50

Sunday, Feb 16, 2014 at 12:50
You are correct I should have pointed out the fact that I was talking about dc-dc chargers that have a solar controller built in.

The sparky has wired the Anderson plugs into the BMS Battery Management System in the CT and also the BCDC1240.
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FollowupID: 808783

Follow Up By: Member - John and Val - Sunday, Feb 16, 2014 at 13:17

Sunday, Feb 16, 2014 at 13:17
Yes Evaredy. I wasn't looking to disagree with you, or even start the usual blistering war that seems to accompany any electrical discussion here!

Cheers

John
J and V
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FollowupID: 808787

Reply By: johno - Saturday, Feb 15, 2014 at 19:59

Saturday, Feb 15, 2014 at 19:59
Thanks for replies.Not knowing much about electrics I was thinking it would be much like when charging through the car alternator when driving as solar would be charging at the same time wouldn't it.
AnswerID: 526528

Follow Up By: dieseltojo - Saturday, Feb 15, 2014 at 23:30

Saturday, Feb 15, 2014 at 23:30
I believe that if you install an additional panel it should be in the same power range as the original within 15%.

Otherwise the lower level panel will reduce the effectiveness of the larger panel to that of the smaller one.

This was advice from a panel dealer.
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Reply By: The Bantam - Sunday, Feb 16, 2014 at 12:37

Sunday, Feb 16, 2014 at 12:37
just to sumarise

a single regulator is looking for a direct relationship with a single battery or properly arranged group of batteries.

running two regulators into one battery...yeh it may work....but how those two regulators inter react is a lotery.....it may work well ( good luck with that) or it may be a large backward step...best avoided.

There are possible issues with running two dissimilar pannels into a single regulator.
With a bit of luck, the anti back feed diodes will sort out some of the issues and both pannels will make SOME contribution... will that be equal or maximim...hmm good question..... bit of a lottery there too.

The best option is two identical pannels.....that would be nice.

Remember the regulator needs to be big enough to handle both pannels.

If you have the instruments and a few smarts...or access to someone who does......you should be able to test how well your two pannels will work into a single suitable regulator.

Otherwise think about disposing of what you have and fitting two new pannels and a good regulator.

cheers
AnswerID: 526569

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