Warwick XL - Gauge of the solar connection?

Good evening,

In our Warwick XL 2018 we have a standard 90W solar panel.
Since we are about to replace our panels I was wondering if I could manage to re-use the current wires if I can keep the Amps down in our new installation
Does anybody know the size of the installed wires? Could they be 1,5 mm2? Or even better 2,5mm2?

Thanks a lot for any input

We are going to replace our 80W (you were right, not 90W) with 2 x 105 semiflexible Sunpower based Solara Power M  S465M34 [You must be registered and logged in to see this link.]

These will be managed by a Victron MPTT SmartSolar 75/15
In general, Victron suggests ensuring that the PV voltage is always 5V or higher than Battery Voltage. One way to do that is to wire the panels in series so PV voltage is doubled.
One side benefit is that Amp are half and therefore requirements for the cable are lower.

These panels use a little external cell protector that makes it easy deciding/wiring serial or parallel before the cable is connected to the solar charge controller
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That is why my hope is that the existing cable can carry the Amp of 2 panels in series (6.8)
The only drawback I know about serial panel wiring is partial shading and I don't even know if this is still actual with modern panels

I will answer my own question since I managed to get in touch with a very kind skilled Sargent Ltd representative and the conclusion could be useful for others.
According to Sargent and based on the pictures I have sent (also attached here), the size of the cable is 1,5mm2 which means that for sure will support the two new panels wired in series (maybe barely supporting them when wired in parallel)


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Dbvwt wrote:Just for info, if your stock solar install is like many others, you will probably find that the Sargent wiring is connected to the cable that came with the solar panel somewhere in the area where the cable enters the van roof.
That seems to be A/S policy rather than a single cable for the whole route.

Thanks for the interesting detail!
Do you know if the junction is accessible from the roof under the white box? (see red arrow in picture)
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gobsmaked, that's an interesting solar installation you've seemingly already got there, does it have a motorised mount to follow the sun? I have seen combined satellite dishes and solar panels. I've not seen any data on the extra performance comparing a horizontal panel with one which is able to follow the sun, matching both elevation and azimuth during the day.

My understanding is that if you have matching solar panels you can choose series or parallel, but with different sizes then it's series that's recommended.

I agree too that if you are adding a second panel then with a series connection made on the roof you should be able to use the existing wiring, the current will be about the same, it's the voltage that will be higher, all OK though, just the shading of one panel which might well be more a theoretical issue than a practical one.

My Sargent solar controller's maximum was 120W, with 2 x 80W I use a directly connected 250 Votronic MTTP type Duo controller.

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gobsmacked wrote:

Dbvwt wrote:Just for info, if your stock solar install is like many others, you will probably find that the Sargent wiring is connected to the cable that came with the solar panel somewhere in the area where the cable enters the van roof.
That seems to be A/S policy rather than a single cable for the whole route.

Thanks for the interesting detail!
Do you know if the junction is accessible from the roof under the white box? (see red arrow in picture)
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no as the picture shows

Relaxez-Vous wrote:gobsmaked, that's an interesting solar installation you've seemingly already got there, does it have a motorised mount to follow the sun? I have seen combined satellite dishes and solar panels. I've not seen any data on the extra performance comparing a horizontal panel with one which is able to follow the sun, matching both elevation and azimuth during the day.
...

Thanks, actually what you see is (was) simply our satellite antenna. Clever idea of a combined satellite/solar to take advantage over the pointing system.
We are stripping down ours and as you can see in this picture, we have removed both the satellite and tv antennas, the second panel will be placed where the TV antenna was. (black gaffer tape covering the hole)
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Relaxez-Vous wrote:
...
I agree too that if you are adding a second panel then with a series connection made on the roof you should be able to use the existing wiring, the current will be about the same, it's the voltage that will be higher, all OK though, just the shading of one panel which might well be more a theoretical issue than a practical one.
...

Yes, worse case we can try to rewire the panels in parallel. The handy thing is these panels have cell protector boxes that make it easy to change the wiring.

Relaxez-Vous wrote:
My Sargent solar controller's maximum was 120W, with 2 x 80W I use a directly connected 250 Votronic MTTP type Duo controller.

Same as our EC500. I read a lot in the forum about the Votronic Duo, but for the solar charger I have opted for a Victron MPTT 75/15, I still need to figure out the next component for charge the vehicle battery. (I might be wrong but it seems so far that EC500 is doing that for me.

If you want you can follow the ongoing modification we are making at our van here: [You must be registered and logged in to see this link.]

glyne lock wrote:[You must be registered and logged in to see this link.]
no as the picture shows

Thanks, I will remove the cover and try to fish the cable the connects to the EC500 up, otherwise, I will simply use cut the solar cable at length.

Dbvwt wrote:If doing a quality upgrade on the solar setup then removing and refitting the gland into the van would be part of my project for the relatively cheap cost of a new fixture and some Sikaflex. At the same time, you could investigate the cable situation and do it to a high standard that you know and can trust.
Not exactly necessary perhaps but the way I’ve always done things!

I agree with you regarding the gland, we will remove it and replace it with this with a hole at the bottom and plenty of sikaflex [You must be registered and logged in to see this link.]
inside that box, I will have the cell protectors wired in series and then connected to the original cable that for now is completely sufficient.

Regarding the cable, we will wait, I will always be able to open the box and go through the "painful" operation of running a 2,5mm2 or bigger cable)

When wiring up the panel on our Trooper, I had originally planned to use 6mm2 cable because the distance is quite long and the route convoluted (so you don't see the cables when the roof is up), but the problem is that 6mm2 is a pretty big and inflexible cable!

So we had to settle for smaller - IIRC we went with 4mm2, and even that can be a bit of a pain in tight corners.

Caraman wrote:The EC700 thread started by Marconi https://www.autosleeper-ownersforum.com/t32226p50-ec700?highlight=EC700 seems to recommend 6 mm (4 mm as a minimum) for all the solar connections.  If going to the expense and trouble of fitting a new controller outside of the ECxxx or fitting an additional panel series or parallel, surely its best to bypass as much of the existing 1.5 mm wiring as possible by cutting it close to where it enters the van roof and connecting it to a new 6 mm wiring all the way to the new controller, which should be as close to the habitation/leisure battery as possible so its 6 mm connecting cable can be as short as possible and perhaps not fused?

I had a look at the thread my Marconi, very interesting! Thanks. The table that describes the size of the wire is for 12V systems. That implies the usage of parallel wiring. Since we will do serial wiring of 2 x 12V Panels, it becomes a 24V system, this creates a much lower amperage. (6,3 for our panels) with a total VoC of 43,38 in normal weather condition. See example here from Victron
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Using this voltage drop calculator I got a fine 1,53%:
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Should I choose to wire the panels in parallel, the 1,5 mm2 wire is absolutely not enough (6,13% voltage drop). Then for sure, I will run the biggest wire I can to make it future-proofed

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