Extra solar panel connection ,advice please

Submitted: Wednesday, Jan 02, 2019 at 10:26
ThreadID: 137634 Views:3223 Replies:3 FollowUps:9
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I have a caravan with 2x150 w solar panels on the roof feeding to a controller ( 30 amp )mounted inside the van and then to 2 x 140 amp agm batteries to run fridge ,tv ,pump etc.

I would like to add more solar panels but there isnt roof space available.

I also have 2 x 80 w panels fixed to the roof rack of my vehicle ,these have their own controller mounted near the auxillary 2 c wet cell agm batteries in the rear of the vehicle. ( this was installed some years ago to run a fridge freezer hf radio and other accesories when travelling with a swag etc ,no caravan.

Question ...if i simply run correct gauge wire from the cars solar panels connected after their controller (bypassing the wet cell agms )onto the vans batteries wouldnt this increase the solar harvest into the van..?? Effectively giving me 2 x 150 w plus 2 x 80 watts into the vans batteries.

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Reply By: noggins - Wednesday, Jan 02, 2019 at 10:52

Wednesday, Jan 02, 2019 at 10:52
I have similar to your setup except that I have 360W of solar on the van's roof.
I also have an extra portable solar for the times I'm parked in the shade.

I have an Andersen plug on the draw bar that connects to the input from the solar.
So when the portable panel is plugged in it gives me another 140W of solar using the 30A regulator in the van.
The van has 2 x 120 Ah batteries.

The ute has a further 2 x 120Ah batteries and a 160W of solar on the roof of the canopy, I have a set of switches and cables so I can either link that solar to the van's batteries or link the ute batteries to the van ( giving me 480Ah of battery and a total of 560W of solar )

We travelled Aus last year and only had to run the Genni for the A/C in the Northern Summer.
AnswerID: 622960

Follow Up By: Pepper - Wednesday, Jan 02, 2019 at 11:20

Wednesday, Jan 02, 2019 at 11:20
Thankyou for the reply , do your 160 w on the canopy feed through their own regulator to the vans batteries (bypassing the vans regulator ) or do they also feed current through the vans regulator ?

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Reply By: Peter_n_Margaret - Wednesday, Jan 02, 2019 at 12:30

Wednesday, Jan 02, 2019 at 12:30
Yes it will work, but it would be better if the second controller was close to the batteries.
OKA196 motorhome
AnswerID: 622962

Follow Up By: RMD - Wednesday, Jan 02, 2019 at 12:42

Wednesday, Jan 02, 2019 at 12:42
Might work, but if there is any noticeable resistance and voltage drop in the delivery cabling, the regulators might shut off their regulating because of the pulsing nature of the varying voltage as switching happens.
FollowupID: 896034

Reply By: RMD - Wednesday, Jan 02, 2019 at 12:38

Wednesday, Jan 02, 2019 at 12:38
What type of solar controllers do you have on each setup? Are they PWM or MPPT regs?

With some systems the detection of battery voltage will be affected if it detects the pulses or different voltage level from elsewhere.
If you van has an MPPT controller which at least runs as MPPT while doing bulk charging you can use the van solar panels in series, provided the regulator is able to take the double input OC voltage. That means you will get half the current flowing in the panel side of reg but able to begin charging earlier and for longer as sun lowers. The MPPT section converts the higher energy level into just as much input to battery or moreso in some cases. The fact it has the potential, NO pun, to be well above battery voltage for more hours, means there will be significant greater charge being actually deliver to the batteries of the van.

I have recently done the above,with/to a friends caravan who could never get his batteries to be near or fully charged. Now with the double input voltage and MPPT controller of suitable rating, all over night loads are easily met and batteries are on float charge around lunchtime, instead of being low charge near evening.

You could simply plug the vehicle solar delivery taken from "before" the cars regulator, into the vans reg. ie in parallel with the van solar input and if the van reg can handle the additional amps, all van batteries should charge better.
AnswerID: 622963

Follow Up By: Pepper - Wednesday, Jan 02, 2019 at 15:23

Wednesday, Jan 02, 2019 at 15:23
The 160w on the vehicle is a pwm cheap unit and the van has a 30 amp powertech mppt unit.

Cant simply plug the cars output into the vans regulator because the wires from the vans panels run inside the wall and roof cavity of the van .

I can run the wires fron the cars panels to the vans regulator as you suggest but not neatly and out of site , not wanting to cut any interior panneling.
FollowupID: 896039

Follow Up By: RMD - Wednesday, Jan 02, 2019 at 17:18

Wednesday, Jan 02, 2019 at 17:18
Where is the MPPT reg situated? If you can fit a cable from outside, ie boot or near batteries perhaps, that wire with anderson on one end and the other to the MPPT solar reg input, ie, in parallel with the vans solar wire, should be easy enough. Shouldn't have to create panel holes. Maybe enlarging current cable holes a little.
In the van we did 6 days ago, a large dual cable was taken from under van, through the floor, up the inside corner of cupboards and drawn out to the roof hole where it linked the, in series, solar panels. So something similar from anderson at floor level to where the reg is should be achieveable.
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Follow Up By: Pepper - Wednesday, Jan 02, 2019 at 20:10

Wednesday, Jan 02, 2019 at 20:10
The mppt regulator is attached inside a cupboard above a window ,the cupboard sits above the window and attaches to the roof panel ...no gaps..on the drivers side of the van..the batteries are under the lounge seat on the left hand side of the van ...the batteries sit on the floor..there is no way i can see to run the wireing from an external point to the mppt controller without cutting a hole somewhere ..but i will have another look as per your suggestion ..thankyou..
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Follow Up By: peteC - Thursday, Jan 03, 2019 at 00:02

Thursday, Jan 03, 2019 at 00:02
Why not remove the controller from its current location, join the wires from battery and solar so you have a direct cable that comes from the van solar panel to the battery area. Remount the controller somewhere near the battery. Connect new wires to the battery from the controller. You can then run a cable from controller to external Anderson plug for your additional solar panels.
Note I would highly doubt anything would be powered off the current cable to battery from the existing controller but might be worth checking.
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Follow Up By: Pepper - Thursday, Jan 03, 2019 at 12:01

Thursday, Jan 03, 2019 at 12:01
PeteC that is a great idea thankyou will have a look at that.
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Follow Up By: Member - nickb "boab" - Thursday, Jan 03, 2019 at 22:14

Thursday, Jan 03, 2019 at 22:14
I've just been looking at redarc website for 10&20 amp regulators etc & i can't see anywhere they say mppt ?? only pwm ,
is that the case ? thought they would be MPPT ?
any comment .
regards nick
Cheers Nick b

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Follow Up By: Frank P (NSW) - Friday, Jan 04, 2019 at 14:30

Friday, Jan 04, 2019 at 14:30

In Redarc's product manual which covers all their solar regs, it states that all their regs are PWM.


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