Solar panel install - correct wire size

[RedWhiteMonkey]

Good morning,

I’m looking for some help with the planning of my proposed solar panel install on a 2022 T6.1 Beach. I think I’ve read through just about every solar thread on this forum, there is some very useful advice and ideas. The one main question that remains in my head is what gauge wire I should use.

I have looked at Solar Camper Solutions offerings and seen quite a lot of helpful posts from Roger. If I were based in the UK I would probably order from him, but I’m an Englishman living in Germany which makes that more complicated. Whilst Roger delivers to Germany my previous experiences with UK and German customs (thanks Brexit) puts me off importing. I am in discussions with my wife about this and it is still potentially an option.

I want to put one panel on the van roof. We only need it to extend the off grid running of a Dometic CFX 35 compressor fridge. I am pretty sure one panel will meet our requirements but I will build in scope for adding a second panel anyway. I am confident enough to make a cable and do the install. At the moment I am tending towards fabricating my own aluminium frame to attach into the roof rails, although there are several good looking mounting solutions available here in Germany if I decide to pay for them.

I am looking at using a 130W panel (https://greenakku.de/Solarmodule/Fl...ibles-Solarmodul-doppel-ETFE-130Wp::4248.html) connected to a Victron 75/15 MPPT to give the option fit a second panel later. I estimate that the wire run from the panel to the MPPT is no more than 5 metres and from the MPPT to battery is no more than 4 more metres.

Doing all the calculations and looking at sites that calculate wire gauge I think 2.5mm2 diameter wire is safe. I would prefer 4mm2 diameter wire for more safety and more efficiency (although this is probably neglible) but that makes the curly cable roof connector difficult. This curly cable is the only bit I am having difficulty sourcing. I have found 2.5mm2 and 4.0mm2 versions for sale on a Swiss website but the price and delivery costs are outrageous, so I would make one. Sourcing a 2.5mm2 curly cable seems possible for a reasonable price. Sourcing a 4mm2 one is more difficult, I have found them on the likes of Alibaba but I’m a bit cautious with those.

The question therefore is whether 2.5mm2 diameter cable is safe for a 130W solar setup or safe for a potential 260W solar setup? I think it is but would appreciate other people’s thoughts and knowledge on this.

Thanks in advance.

 

[babble]

i can't really help, but i suspect the Alibaba ones are fine (indeed, they are probably made by the same source of many of the other ones you find)

 

[RedWhiteMonkey]

You're probably right on Alibaba, stuff like that pretty much all comes from China.

Having said that, the straight cable I'm looking at is made by Lappkabel. Coincidentally their factory is 5 minutes walk from my house, I'm half tempted to go ask them if they have any off cuts going spare!

 

[pluc99]

I can't imagine that German customs will be any more of a problem than Swiss customs was was for me. It's basically handled by the delivery service who will bill you for it. I'm certainly very happy that I ordered from Roger.

 

[RedWhiteMonkey]

I can't imagine that German customs will be any more of a problem than Swiss customs was was for me. It's basically handled by the delivery service who will bill you for it. I'm certainly very happy that I ordered from Roger.

I certainly don't want to start a Brexit discussion, but since that event the whole sending and received to and from the UK has become problematic. We've had Christmas presents, birthday presents, Easter eggs, etc. for the kids either "lost" by customs or had to pay stupid fees to get them released. At a commercial level, I work in export for a manufacturer here and our UK customers are fed up with customs.

Switzerland might not be EU but trade being Germany and there has been unchanged for many years. The only thing that puts me off them is the very high purchase and shipping costs, nearly 100€ to send a cable from Switzerland to Germany is a joke.

Back to the thread, I actually quite fancy the challenge of making and installing the system. I just want confirmation that my thinking on wire gauge is correct. I think I might run 2.5mm2 from the panel to the MPPT and 4mm2 from the MPPT to battery. As I understand it, the MPPT controls the output and can sometimes send a larger load.

 

[babble]

My mum sent me over two old books and an old map from the UK to Belgium the other day. She put a nominal value of €1 on the contents. I was asked to pay €23 to receive the package. It's basically now impossible/impractical to send thinks over.

 

[dspuk]

Good morning,

I’m looking for some help with the planning of my proposed solar panel install on a 2022 T6.1 Beach. I think I’ve read through just about every solar thread on this forum, there is some very useful advice and ideas. The one main question that remains in my head is what gauge wire I should use.

I have looked at Solar Camper Solutions offerings and seen quite a lot of helpful posts from Roger. If I were based in the UK I would probably order from him, but I’m an Englishman living in Germany which makes that more complicated. Whilst Roger delivers to Germany my previous experiences with UK and German customs (thanks Brexit) puts me off importing. I am in discussions with my wife about this and it is still potentially an option.

I want to put one panel on the van roof. We only need it to extend the off grid running of a Dometic CFX 35 compressor fridge. I am pretty sure one panel will meet our requirements but I will build in scope for adding a second panel anyway. I am confident enough to make a cable and do the install. At the moment I am tending towards fabricating my own aluminium frame to attach into the roof rails, although there are several good looking mounting solutions available here in Germany if I decide to pay for them.

I am looking at using a 130W panel (https://greenakku.de/Solarmodule/Fl...ibles-Solarmodul-doppel-ETFE-130Wp::4248.html) connected to a Victron 75/15 MPPT to give the option fit a second panel later. I estimate that the wire run from the panel to the MPPT is no more than 5 metres and from the MPPT to battery is no more than 4 more metres.

Doing all the calculations and looking at sites that calculate wire gauge I think 2.5mm2 diameter wire is safe. I would prefer 4mm2 diameter wire for more safety and more efficiency (although this is probably neglible) but that makes the curly cable roof connector difficult. This curly cable is the only bit I am having difficulty sourcing. I have found 2.5mm2 and 4.0mm2 versions for sale on a Swiss website but the price and delivery costs are outrageous, so I would make one. Sourcing a 2.5mm2 curly cable seems possible for a reasonable price. Sourcing a 4mm2 one is more difficult, I have found them on the likes of Alibaba but I’m a bit cautious with those.

The question therefore is whether 2.5mm2 diameter cable is safe for a 130W solar setup or safe for a potential 260W solar setup? I think it is but would appreciate other people’s thoughts and knowledge on this.

Thanks in advance.

Save your time and hassle and just get one of Rogers.

 

[RedWhiteMonkey]

Save your time and hassle and just get one of Rogers.

I have no doubts about the quality of Roger's product and quality of Roger's service. I have doubts about the quality and service of UK and German customs, which potentially will cost me more time and hassle over all. I also quite fancy the challenge of doing it all myself, I am pretty practical and figure if I can run CNC machine I can install a solar panel.

 

[Kingfisher]

The question therefore is whether 2.5mm2 diameter cable is safe for a 130W solar setup or safe for a potential 260W solar setup? I think it is but would appreciate other people’s thoughts and knowledge on this.

Current to and from the Victron MPPT 75/15 should never get higher than 15 A, so 2.5 mm2 cable does seem a safe option. Note that there is a warning about the type of cable in the Victron manual (should be flexible, multi-stranded cable).

1. Safety precautions

www.victronenergy.com

 

[dspuk]

I have no doubts about the quality of Roger's product and quality of Roger's service. I have doubts about the quality and service of UK and German customs, which potentially will cost me more time and hassle over all. I also quite fancy the challenge of doing it all myself, I am pretty practical and figure if I can run CNC machine I can install a solar panel.

Cool, although to be fair, I have no issues with properly tracked items. Biggest issue is always tax now which I assume also goes the other way.

The reality of the kit is it is two wires, a controller and a panel.

 

[Steve1]

Good morning,

I’m looking for some help with the planning of my proposed solar panel install on a 2022 T6.1 Beach. I think I’ve read through just about every solar thread on this forum, there is some very useful advice and ideas. The one main question that remains in my head is what gauge wire I should use.

I have looked at Solar Camper Solutions offerings and seen quite a lot of helpful posts from Roger. If I were based in the UK I would probably order from him, but I’m an Englishman living in Germany which makes that more complicated. Whilst Roger delivers to Germany my previous experiences with UK and German customs (thanks Brexit) puts me off importing. I am in discussions with my wife about this and it is still potentially an option.

I want to put one panel on the van roof. We only need it to extend the off grid running of a Dometic CFX 35 compressor fridge. I am pretty sure one panel will meet our requirements but I will build in scope for adding a second panel anyway. I am confident enough to make a cable and do the install. At the moment I am tending towards fabricating my own aluminium frame to attach into the roof rails, although there are several good looking mounting solutions available here in Germany if I decide to pay for them.

I am looking at using a 130W panel (https://greenakku.de/Solarmodule/Fl...ibles-Solarmodul-doppel-ETFE-130Wp::4248.html) connected to a Victron 75/15 MPPT to give the option fit a second panel later. I estimate that the wire run from the panel to the MPPT is no more than 5 metres and from the MPPT to battery is no more than 4 more metres.

Doing all the calculations and looking at sites that calculate wire gauge I think 2.5mm2 diameter wire is safe. I would prefer 4mm2 diameter wire for more safety and more efficiency (although this is probably neglible) but that makes the curly cable roof connector difficult. This curly cable is the only bit I am having difficulty sourcing. I have found 2.5mm2 and 4.0mm2 versions for sale on a Swiss website but the price and delivery costs are outrageous, so I would make one. Sourcing a 2.5mm2 curly cable seems possible for a reasonable price. Sourcing a 4mm2 one is more difficult, I have found them on the likes of Alibaba but I’m a bit cautious with those.

The question therefore is whether 2.5mm2 diameter cable is safe for a 130W solar setup or safe for a potential 260W solar setup? I think it is but would appreciate other people’s thoughts and knowledge on this.

Thanks in advance.

For my work in medical and lab equipement we use this table

We usually try to stick as close to the 10C rise as possible, 35C is deemed acceptable, so between the 2 lines is acceptable, but can make the wires quite hot i.e. in a 30C ambient 65C wires are a bit scary.
I think 2.5mm2 is equivalent to 14AWG so ideally good for 8 A or a little above. I think your 1, 130W panel would be about 10A worst case so should be absoloutely fine. But for 260W you are looking at 20A which is too much for 14AWG (even if the controller is limited to 15A max as mentioned above which I guess depends on the one chosen, it is pushing it to the 35C rise, which I would say is not ideal)
Note this table does have an accompanying multiplier table but I think for you, you have a "+" and "-" wire together so your multiplier is 1.


All that said medical and laboratory instrumentation wiring is perhaps more conservative than other industries so I might well be wrong !

Personally though, I would use the 2.5mm2 for the single panel 10A, but not for the double panel 20A, and I would be nervous still even if you said the controller limit is 15A so I would use thicker wire for that too.

 

[RedWhiteMonkey]

Thanks for all the input so far. I did quite a lot more reading and Youtube video watching last night. I suspect that I won't add a second panel unless I am really unhappy with the performance of just one panel, but research seems to suggest that one panel will more than meet my needs. Having said that the price difference between cabling is not much so I've decided that I'll run 4mm2 from the panel(s) to the MPPT (4mm2 is the largest dia. curly cable I can find) and 6mm2 from the MPPT to the battery. This is probably overkill but it'll give me peace of mind and a minor efficiency advantage.

 

[Roger Donoghue]

I use 2.5mm2 from the panel/s to the MPPT unit.

I use 2mm squ to link the panels, and for the flat cable option.

2mm squ thinwall nominal current is 25amp.

1 x 100w panel will max at 5.5 amps.
2 x 100w panels 11 amps
3 x 100w panels 17.5amps

This is in perfect sun with the roof up.

The cable run is 1 metre or less into the van, with the multi panel link sections being less than 75cm max (and the links are only ever carrying 2 panels max). The voltage drop is negligible and it allows for neat cable installation. The cable doesn't even get warm. Any larger cable would make the curly cord much bigger, the connectors much, much bigger, and the hole through the taigate grommet bigger than I'd be happy with.

Regarding shipping to Germany (and I know you are happy building your own) but it needs saying for others interested - your examples you emailed me were gifts sent to you.

Gifts are problematic all over Europe because customs doesn't believe they are gifts. They think people are pulling a fast one. When I send small items for free to cusomers abroad, like a small cable adapter, or a replacement bracket etc - I put a value of £1 or £2 on the customs form so it gets through. Putting £0, / gift / sample guarantees it gets stuck for 2 months.

Shipping all over Europe is painless and simply requires me to fill in a form stating the shipping value, goods value, and item description and HS tarrif code.

When non - UK customers put their address in on my site, the UK VAT is removed. When the package arrives in Europe, their local VAT is added back on, plus a small handling fee from the carrier. That's it.

I successfully ship all over the EU (And Aus, Jap, NZ) with hardly any issues. One or two of the Eastern Europe countries can be a little bit "prickly" - I have to enclose CE certs shipping to some, but on the whole it is painless and relatively fast.

What has happened is the customs element has slowed things down a bit. My EU deliveries typically take 2 weeks door to door, but sometimes much less, like 4 days to France.

 

[RedWhiteMonkey]

Thanks Roger, very helpful.

 

[Brian Schulz]

I certainly don't want to start a Brexit discussion, but since that event the whole sending and received to and from the UK has become problematic. We've had Christmas presents, birthday presents, Easter eggs, etc. for the kids either "lost" by customs or had to pay stupid fees to get them released. At a commercial level, I work in export for a manufacturer here and our UK customers are fed up with customs.

Switzerland might not be EU but trade being Germany and there has been unchanged for many years. The only thing that puts me off them is the very high purchase and shipping costs, nearly 100€ to send a cable from Switzerland to Germany is a joke.

Back to the thread, I actually quite fancy the challenge of making and installing the system. I just want confirmation that my thinking on wire gauge is correct. I think I might run 2.5mm2 from the panel to the MPPT and 4mm2 from the MPPT to battery. As I understand it, the MPPT controls the output and can sometimes send a larger load.

We live between Uk & Bavaria, and it’s been total chaos, sending stuff back-and-forth since brexit. We Do understand your comments.! Red white monkey! Sorry
can’t help you with the cables as I’m looking into the solar situation myself!.

 

[klokanoid.042]

While I was planning my solar installation, I found these guys for curly cables on ebay: https://www.ebay.com/str/advancedretractablecablesltd

They can do custom lengths, but at the end I decided to go without curly.

As I’m not in UK or EU, every premade solution was too expensive (shipping, customs, local vat add 50% on price), so I did it on my own - 130W panel glued to two aluminium L profiles and cable routed by side of door (without cutting anything). Most complicated thing was interior work - routing cable to and from controller.

Two years and panel still didn’t fall off

Edit: cable that came with panel says 2x2.5mm.

 

[waneos]

Hi,

Good morning,

I’m looking for some help with the planning of my proposed solar panel install on a 2022 T6.1 Beach. I think I’ve read through just about every solar thread on this forum, there is some very useful advice and ideas. The one main question that remains in my head is what gauge wire I should use.

I have looked at Solar Camper Solutions offerings and seen quite a lot of helpful posts from Roger. If I were based in the UK I would probably order from him, but I’m an Englishman living in Germany which makes that more complicated. Whilst Roger delivers to Germany my previous experiences with UK and German customs (thanks Brexit) puts me off importing. I am in discussions with my wife about this and it is still potentially an option.

I want to put one panel on the van roof. We only need it to extend the off grid running of a Dometic CFX 35 compressor fridge. I am pretty sure one panel will meet our requirements but I will build in scope for adding a second panel anyway. I am confident enough to make a cable and do the install. At the moment I am tending towards fabricating my own aluminium frame to attach into the roof rails, although there are several good looking mounting solutions available here in Germany if I decide to pay for them.

I am looking at using a 130W panel (https://greenakku.de/Solarmodule/Fl...ibles-Solarmodul-doppel-ETFE-130Wp::4248.html) connected to a Victron 75/15 MPPT to give the option fit a second panel later. I estimate that the wire run from the panel to the MPPT is no more than 5 metres and from the MPPT to battery is no more than 4 more metres.

Doing all the calculations and looking at sites that calculate wire gauge I think 2.5mm2 diameter wire is safe. I would prefer 4mm2 diameter wire for more safety and more efficiency (although this is probably neglible) but that makes the curly cable roof connector difficult. This curly cable is the only bit I am having difficulty sourcing. I have found 2.5mm2 and 4.0mm2 versions for sale on a Swiss website but the price and delivery costs are outrageous, so I would make one. Sourcing a 2.5mm2 curly cable seems possible for a reasonable price. Sourcing a 4mm2 one is more difficult, I have found them on the likes of Alibaba but I’m a bit cautious with those.

The question therefore is whether 2.5mm2 diameter cable is safe for a 130W solar setup or safe for a potential 260W solar setup? I think it is but would appreciate other people’s thoughts and knowledge on this.

Thanks in advance.

I am looking for the same solar panels. How did it go? did you do yourself the mounting or buy it to someone?

Could you please share your shopping list what you used for the instalation?

 

[RedWhiteMonkey]

I bought, made and installed the solar panel myself. It cost me just over 400€ but prices are possibly not relevant as I purchased everything in Germany and I don’t know what they would cost elsewhere.

I fitted an ECO-Worthy 130W flexible panel that I fixed to an aluminium frame that I made from aluminium profiles I bought from the local hardware shop. The solar panel is connected to a Victron 75/10 (75/15 is a better choice if you want to add more panels later). The controller is stuck to the van in the jack compartment with industrial strength Velcro. I used 2.5mm section solar cable and found a curly cable on ebay to account for the pop up roof. There are various connectors and fuses needed. Routing the cable through the van is a little scary but not actually that difficult.

 

[waneos]

Hi,

Thank you for the answer. Can you share the link for the curly cord?

For the rest of wiring, did you use 2.5mm2 or 4mm2¿

 

[dspuk]

Hi,

Thank you for the answer. Can you share the link for the curly cord?

For the rest of wiring, did you use 2.5mm2 or 4mm2¿

What Size Cable for 12V Solar Panel - Solar Panel Wire Size

What size cable for 12V solar panel? Let's unveil why choosing the correct wire gauge is crucial when installing solar panels.

avasolar.com

TLDR? 2.5.

 

[RedWhiteMonkey]

Yes, 2.5mm2. The curly cable is 4mm2, but only because it's all I could find. I bought it from eBay in Germany, sorry but it's no longer available.

 

[waneos]

If you have several solar panels, the wire size will depend on if the panels are connected series or parallel right?

I am looking for two solar panel greenakku 130W, where the max A = 6.67A. So if I connect two panels in serie, the A = 6,67A right?

 

[dspuk]

If you have several solar panels, the wire size will depend on if the panels are connected series or parallel right?

I am looking for two solar panel greenakku 130W, where the max A = 6.67A. So if I connect two panels in serie, the A = 6,67A right?

Still 2.5

 

[waneos]

Thanks for the answers.

 

[JuanVecino2023]

Resurrecting an old thread.

What diameter cable is needed between the Victron output and the leisure battery? @Roger Donoghue I have a used kit of yours and this is the only piece I don’t have.