Solar wiring 10x200w panels

[TankFish]

Hello everyone. I'm planning (nothing bought yet except some wire, tools, LiFePO4 cells and ordered BMS from overkill) to install 10x200w panels on my 42' 5th wheel RV. After measuring, that is what I can fit tops. My rig is a 50amp, so I plan to buy two 3000w Victron MultiPlus 24v inverter/chargers to be able to feed the two 120v feeds (split phase) in my rig. To keep this part short, mostly going all Victron for a lot of it.

My main concern is connecting these panels. How do people wire them up? They are sold with 10ga wire and I see people parallel and Series linking these in pictures and it looks like the wire that came on the panels. If each 12v 200w panel is putting out about 5.2 amps, linking 10 would be 52 amps. Now if you parallel one side and parallel the other, then series the sides together to get 24v you would still be at 25 or so amps right? A 10ga wire is rated for 30amps. Wouldn't these start to heat up around noon at the most sun exposure?

I guess what I am getting at, is I am trying to figure out how to safely wire 10 panels together, to get the 24v I want and the wires to be safe and not burn up my trailer.

A little reassurance from you guys would be great. How would you wire them? Would you tear open the doide om the panel and solder on 8ga? If I did do 8ga, my solar prep on my roof will have to be redone as well, as it is 10ga and that doesn't look fun to rewire (who knows how they ran that through the walls). Thanks for any help and insight.

Oh and please correct me if I'm wrong. I have an IT background and this is my first DIY solar project, so my knowledge is basically just researching this stuff, no hands on. I want to do it right, especially with buying about 10 grand worth of stuff soon. I definitely don't want to break anything.

 

[Forbisher]

If each 12v 200w panel is putting out about 5.2 amps, linking 10 would be 52 amps. Now if you parallel one side and parallel the other, then series the sides together to get 24v you would still be at 25 or so amps right? A 10ga wire is rated for 30amps. Wouldn't these start to heat up around noon at the most sun exposure?

I guess what I am getting at, is I am trying to figure out how to safely wire 10 panels together, to get the 24v I want and the wires to be safe and not burn up my trailer.

Look up the specs on those so called "12"V 200w panels.
Voc
Vmp
Imp
Isc
Volts x Amps = watts
12V x 5.2A does not = 200 watts so you are way off on the Vmp and Imp on those 200w panels.

You have it backwards as you first connect panels in Series up to the max volts input of your SCC compensated for temperature then Parallel connect those seried strings.

What is the max volts input of your Victron MPPT SCC?

 

[TankFish]

Look up the specs on those so called "12"V 200w panels.
Voc
Vmp
Imp
Isc
Volts x Amps = watts
12V x 5.2A does not = 200 watts so you are way off on the Vmp and Imp on those 200w panels.

You have it backwards as you first connect panels in Series up to the max volts input of your SCC compensated for temperature then Parallel connect those seried strings.

What is the max volts input of your Victron MPPT SCC?

Thank you for your reply. I'm very sorry, I've been looking at so many different panels, I forgot the ones I choose were "24v" listed.

These are the specs from the supplier.

• Maximum Power(Pmax): 200W
• Maximum Power Voltage(Vmp): 37.6V
• Maximum Power Current(Imp): 5.32A
• Open Circuit Voltage(Voc): 45.4V
• Short Circuit Current(Isc): 5.83A
• Maximum System Voltage(Vmax): 1000V DC
• Weight: 26.5 lbs
• Dimensions: 58.7 x 26.8 x 1.4 in

So, how would you wire these? I can "fit" 5 on each side. I'm am by no means knowledgeable about parallel and series, still learning, we'll trying to learn. As for the SCC, I chose the Victron MPPT 150/70. It claims to handle the 2000w I plan to put up on the roof of my rig. I don't forsee ever reaching peak performance out of my panels, as they will be roof mounted and the rv spots are never "optimum sun position".

 

[Forbisher]

• Maximum Power(Pmax): 200W
• Maximum Power Voltage(Vmp): 37.6V
• Maximum Power Current(Imp): 5.32A
• Open Circuit Voltage(Voc): 45.4V
• Short Circuit Current(Isc): 5.83A
• Maximum System Voltage(Vmax): 1000V DC
• Weight: 26.5 lbs
• Dimensions: 58.7 x 26.8 x 1.4 in

So, how would you wire these? I can "fit" 5 on each side. I'm am by no means knowledgeable about parallel and series, still learning, we'll trying to learn. As for the SCC, I chose the Victron MPPT 150/70. It claims to handle the 2000w I plan to put up on the roof of my rig. I don't forsee ever reaching peak performance out of my panels, as they will be roof mounted and the rv spots are never "optimum sun position".

No problem about the 24V panels but 200 watts is still 200 watts.
45.4Voc x 3 panels is 136.2V x 1.1 for temp compensation is 149.8V which is just under the 150V max input of a Victron 150 / 70
But 10 panels is not divisable by 3 which would be 9 panels with one left over.
That is 3Series3Parallel.

2 panels in series is 90.8Voc so 10 panels as 2Series5Parallel would be 90.8Voc and 26.6A ( 5 x 5.32A) would work for your layout.

2000watts panels at 24V is 83.3A

How many feet of cable from the panels to the SCC?
At 90Vmp and about 27A you will not need large gauge cable.

 

[Bob Steel]

?
Maximum Power Voltage(Vmp): 37.6V
Maximum Power Current(Imp): 5.32A
5 in series gives 188V input at 5.32 amps max . 2 strings of 5 would still give 5.32 amps per string so into a combiner box would send 10.64 amps to the inverter at 188v max or fed separately to 2 inverters would be 5.32 amps to each.

As I understand it the victron units will tolerate overvoltage and 188 volts is not that much over . Taking into account that is the maximum voltage each string would output the real voltages will be way less than that most of the time ,especially in cloud or rain and being MPP would lower the voltage and increase the current.

 

[TankFish]

No problem about the 24V panels but 200 watts is still 200 watts.
45.4Voc x 3 panels is 136.2V x 1.1 for temp compensation is 149.8V which is just under the 150V max input of a Victron 150 / 70
But 10 panels is not divisable by 3 which would be 9 panels with one left over.
That is 3Series3Parallel.

2 panels in series is 90.8Voc so 10 panels as 2Series5Parallel would be 90.8Voc and 26.6A ( 5 x 5.32A) would work for your layout.

2000watts panels at 24V is 83.3A

How many feet of cable from the panels to the SCC?
At 90Vmp and about 27A you will not need large gauge cable.

Thanks again for getting back with me. So run the 5 on each side in a series and then parallel them together at the roof input?

The length of the cable I couldn't say for sure. I did not run it. My rig came with a 50w panel on the roof, that I plan to remove. It has 10ga wire leading into the roof. From roof to basement floor is about 12'. I would like to say they ran it from the roof, to the wall edge (about 2') then down the wall (10') into the basement (passthrough storage) and ran it across to the connection (about 7'). If they ran it exactly to the source and didn't wrap it another way, id like to say about 20' to where I'll be putting the SCC. I will more than likely trim any slack in the lines once I start digging into them, to give me a nice clean connection (clean as in look) to the SCC. I'm hoping they ran it straight down, but without tearing into the walls, I can't say for sure. I only see the entry and exit.

 

[Forbisher]

2S5P
90Vmp
27A
20 feet one way 40 feet round trip
10 AWG at a low 1.2% voltage drop.
You will need fuses for 5 parallel strings.
Max fuse size should be on the panel specs.
You can play with the inputs by clicking on the calculator.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[Forbisher]

Thanks again for getting back with me. So run the 5 on each side in a series and then parallel them together at the roof input?

The length of the cable I couldn't say for sure. I did not run it. My rig came with a 50w panel on the roof, that I plan to remove. It has 10ga wire leading into the roof. From roof to basement floor is about 12'. I would like to say they ran it from the roof, to the wall edge (about 2') then down the wall (10') into the basement (passthrough storage) and ran it across to the connection (about 7'). If they ran it exactly to the source and didn't wrap it another way, id like to say about 20' to where I'll be putting the SCC. I will more than likely trim any slack in the lines once I start digging into them, to give me a nice clean connection (clean as in look) to the SCC. I'm hoping they ran it straight down, but without tearing into the walls, I can't say for sure. I only see the entry and exit.

No.
2 panels in Series x 5 Paralleled
2S
2S
2S
2S
2S
Series adds the voltage so 90V
Parallel adds the amps so 5.32A x 5
I already guessed 20 feet cable which only needs 10AWG cable for the 2S5P array.

 

[TankFish]

?
Maximum Power Voltage(Vmp): 37.6V
Maximum Power Current(Imp): 5.32A
5 in series gives 188V input at 5.32 amps . 2 strings of 5 would still give 5.32 amps per string so into a combiner box would send 10.64 amps to the inverter at 188v max or fed separately to 2 inverters would be 5.32 amps to each.

Thank you for the reply. I won't be feeding the inverters from the solar. I ordered 16x 280ah LiFePO4 cells from Alibaba (from a vendor found on this forum in china) that my SCC will be charging once I get them and built. The Inverters will be linked to a SPS from shore power and the batteries. Even with 2000w, I won't be able to fully power my RV with just solar. We are stationed in the desert, and the kids like the AC in the day and heat at night (converted my propane furnace to electric). I wish I could get away with one inverter, but because I have a 50amp RV, I have to use two for the full "RV off batteries" with two 120v feeds to my box.

 

[Forbisher]

?
Maximum Power Voltage(Vmp): 37.6V
Maximum Power Current(Imp): 5.32A
5 in series gives 188V input at 5.32 amps max . 2 strings of 5 would still give 5.32 amps per string so into a combiner box would send 10.64 amps to the inverter at 188v max or fed separately to 2 inverters would be 5.32 amps to each.

As I understand it the victron units will tolerate overvoltage and 188 volts is not that much over . Taking into account that is the maximum voltage each string would output the real voltages will be way less than that most of the time ,especially in cloud or rain and being MPP would lower the voltage and increase the current.

188V is way too much for a 150V Victron
But you are incorrectly using Vmp instead of Voc so the max voltage would actually be 45V x 5 panels in Series is 225Voc.
Your advice is incorrect!
5 panels in Series will not work.
3 panels in Series would barely work IF the temps stay above 40°f

 

[TankFish]

No.
2 panels in Series x 5 Paralleled
2S
2S
2S
2S
2S
Series adds the voltage so 90V
Parallel adds the amps so 5.32A x 5
I already guessed 20 feet cable which only needs 10AWG cable for the 2S5P array.

Thank you for the reply and sorry for the confusion. I must need a visual aid. You say
2S
2S
2S
2S
2S

So you mean one side all positives to negatives except the last. Same with negatives to positives except the last. Then same on the other side. Then positive to positive from each side and negative to negative from each side into the SCC? Am I catching this?

 

[Forbisher]

Thank you for the reply. I won't be feeding the inverters from the solar. I ordered 16x 280ah LiFePO4 cells from Alibaba (from a vendor found on this forum in china) that my SCC will be charging once I get them and built. The Inverters will be linked to a SPS from shore power and the batteries. Even with 2000w, I won't be able to fully power my RV with just solar. We are stationed in the desert, and the kids like the AC in the day and heat at night (converted my propane furnace to electric). I wish I could get away with one inverter, but because I have a 50amp RV, I have to use two for the full "RV off batteries" with two 120v feeds to my box.

Please Ignore the post from Bob Steel.
He is incorrect about 188V being ok and is using the lower Vmp instead of Voc which is much higher.
5 panels in series will burn up your 150V max input MPPT

 

[TankFish]

2S5P
90Vmp
27A
20 feet one way 40 feet round trip
10 AWG at a low 1.2% voltage drop.
You will need fuses for 5 parallel strings.
Max fuse size should be on the panel specs.
You can play with the inputs by clicking on the calculator.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Thats a great link thank you.

As for the fuses, I'll need one between each panel or each string or just one before the SCC? I never thought about fuses on the roof.

 

[TankFish]

Please Ignore the post from Bob Steel.
He is incorrect about 188V being ok and is using the lower Vmp instead of Voc which is much higher.
5 panels in series will burn up your 150V max input MPPT

So I will need two SCC's and need to run additional lines? So a line for each side of the RV? Or can I still use one line and somehow split the load near the SCC and just use two?

 

[Forbisher]

So I will need two SCC's and need to run additional lines? So a line for each side of the RV? Or can I still use one line and somehow split the load near the SCC and just use two?

You only need 1 SCC Victron 150V / 70A for your 10 200w panels into a 24V battery.
There will only be 2 10AWG cables connecting to your SCC from the 10 panels after they have been connected in 2 Series 5 Parallel.
You need 5 fuses for the 5 paralled strings of 2 panels in series.
I am going to sleep. Lol
Hopefully I got everything correct.

 

[TankFish]

You only need 1 SCC Victron 150V / 70A for your 10 200w panels into a 24V battery.
There will only be 2 10AWG cables connecting to your SCC from the 10 panels after they have been connected in 2 Series 5 Parallel.
You need 5 fuses for the 5 paralled strings of 2 panels in series.
I am going to sleep. Lol
Hopefully I got everything correct.

A lot of information. Thank you so much for staying up and helping me. I will stay up and research solar fusing now, since they will be exposed to elements and find the best safest way.

 

[TankFish]

So, I got this from the internet. I think this is what you mean by 5 series and 2 parallel. This should be fun to wire.

 

[Forbisher]

So, I got this from the internet. I think this is what you mean by 5 series and 2 parallel. This should be fun to wire.

Nope.
It is 2 Series 5 Parallel not 5S2P
But that diagram looks right.
They make 5 parallel connectors so look on Amazon

 

[TankFish]

Nope.
It is 2 Series 5 Parallel not 5S2P

I'm terrible at this, maybe I should have paid for a professional. I will not give up, I will learn this! This but 10 panels? You can reply in the morning if you are trying to sleep. My brain is just trying to wrap my head around this properly.

 

[Forbisher]

Thats a great link thank you.

Just to confuse you even more if you used 12V 200watt panels that I guess are 20Vmp and 10A then you could connect the 10 panels in 5 Series 2 Parallel.
5 panels in series x 24Voc is only 120V total.
2 parallel x 10A is 20A total.
Newpowa make low Voc panels.