Can I go 4s with these panels and this controller?

[corn18]

My guess is no. I think I am over paneled with 3S and might be over voltage (or too close for comfort) @ 4S.

 

[42OhmsPA]

12V or 24V battery?
Record cold temperatures?

Regardless of answers to the above questions you can't go wrong with 2s2p but you might lose out on a bit of production if you're using a 12V battery.

 

[justinm001]

97.2v should be the max so it shouldn't even be possible to hit 100v... right?

 

[corn18]

I thought that, too until I just did some reading up on panel output voltage vs. temperature. From the spec number to 0 deg C, the Voc will go up 10%, so I will exceed 100V and fry the Victron 100/50.

2S/2P it is.

 

[wiseacre]

I thought that, too until I did some reading up on panel output voltage vs. temperature. From the spec number to 0 deg C, the Voc will go up 10%, so I will exceed 100V and fry the Victron 100/50.

2S/2P it is.

Three shall be the number thou shalt count, and the number of the counting shall be three

I have the same panels and CC
Going to 4s is not a good idea, pushing the VOC max tends to fry a CC
4s is 97.2 VOC at 25C - a dip in the temp will put you over the VOC limit

I just unboxed a 150/70 so I could reconfigure my array allowing 4s strings

 

[corn18]

I have two 100/50 controllers. 3S hooked to each. If I decide to add 2 more panels, I will just wire them 2S/2P to each controller.

 

[42OhmsPA]

97.2v should be the max so it shouldn't even be possible to hit 100v... right?

Wrong. VOC is determined at a nominal operating temp, temperatures below this temp increase voltage.

 

[corn18]

I don't need more panels, but I have room for them and I'm itchin' for a project. It would be really easy to just add another set of wires down to where the other controllers are and have 3 SCC's. Maybe I should do that and install 2x300W panels instead of 2x200W.

 

[justinm001]

Wrong. VOC is determined at a nominal operating temp, temperatures below this temp increase voltage.

You're right. I keep forgetting its the VOC and not just VMP thats temp.

 

[justinm001]

You have a ton of room. If I were you I'd flip some of those panels sideways and then you can double the panels on one side using the existing mounts. Have 3S on one side and 3s2p on other.

 

[42OhmsPA]

I don't need more panels, but I have room for them and I'm itchin' for a project. It would be really easy to just add another set of wires down to where the other controllers are and have 3 SCC's. Maybe I should do that and install 2x300W panels instead of 2x200W.
View attachment 206859
View attachment 206861

You always need more panels and batteries, it's a law.

@justinm001 makes a great point about turning them sideways.
Why 300W when there's 370-400W+ available?...

 

[corn18]

You always need more panels and batteries, it's a law.

@justinm001 makes a great point about turning them sideways.
Why 300W when there's 370-400W+ available?...

What's a good brand/source for 370W or 400W? There's plenty of room between the panels I have up there.

 

[corn18]

There's a local guy with pallets of these for $135 each. Seems easy peasy to just go get two of them and another Victron 150/50 and I'm good to go, right?.

 

[corn18]

Nope, I only have 42" between the existing rows and need room to walk between them. Easiest would just be to add 2x200. Leaves me room to walk and can go 2S/2P and not buy another controller.

 

[justinm001]

Nope, I only have 42" between the existing rows and need room to walk between them. Easiest would just be to add 2x200. Leaves me room to walk and can go 2S/2P and not buy another controller.

Why do you need room to walk between them? If using rails you can easily unscrew a panel or two to walk around

 

[42OhmsPA]

What's a good brand/source for 370W or 400W? There's plenty of room between the panels I have up there.

Lots of options / opinions. I'm running Q-Cells and NE solar.
Craigslist / marketplace / ebay if you only need a handful; Inxeption or Santan if you want a pallet and resell leftovers.

Edit - there are many other options of panel brands.

There's a local guy with pallets of these for $135 each. Seems easy peasy to just go get two of them and another Victron 150/50 and I'm good to go, right?.
View attachment 206881

I don't see any issues with it. I added a 100/20 and 2S NE solar 370W for extra production, works great.

Not a terrible price if you only need a few.
I paid ~$95 a panel delivered when I ordered my pallet of NE Solar 370W.

You could also check for a local Greentech Renewables and see if they will sell to you.

 

[corn18]

Why do you need room to walk between them? If using rails you can easily unscrew a panel or two to walk around

Don't like that idea, especially since I don't need more panels. I want to retain access to everything without having to remove panels. I can fit 12x200W panels and still walk everywhere on the roof.

 

[justinm001]

Why do you need to walk around the roof? Your ACs are in front/rear so you can easily access them with ladders. I'd think it would be easier to put all panels together in the middle and no room around them then leave front/rear open for ACs.

 

[corn18]

Why do you need to walk around the roof? Your ACs are in front/rear so you can easily access them with ladders. I'd think it would be easier to put all panels together in the middle and no room around them then leave front/rear open for ACs.

I have a built in ladder at the rear. Definitely do not want to take another ladder along or remove panels. Pretty simple requirement for me and I will not change it.

 

[justinm001]

I have a built in ladder at the rear. Definitely do not want to take another ladder along or remove panels. Pretty simple requirement for me and I will not change it.

Ahhh I see. I forgot some have ladders on the rear still. I have one of those collaspable ones I keep in a bay and love it.