Fuses between solar panels? Panel>fuse>panel?

[Harmony5000]

If you got 4 panels with the kit, and a pair of Y connectors, that you have in the picture, then they were suppose to be two panels in series, and then parallel the 2 strings of two panels each (2S2P)
Trying to add only one more panel, won't work, and your charge controller is only 520W, so you can't add two more panels.

There were four panels in the kit and enough Y connectors to put them all in parallel. 4 y connectors. Mmm renogy said I could use a 5th panel? I’m only trying to do 5 100watt panels with ratings pictures in an earlier post.

 

[TEV]

This is a 2S2P

 

[TEV]

There were four panels in the kit and enough Y connectors to put them all in parallel. 4 y connectors. Mmm renogy said I could use a 5th panel? I’m only trying to do 5 100watt panels with ratings pictures in an earlier post.

5.85Ax5=29.25A , 10AWG is rated 30A, so you should be ok.

 

[rmaddy]

No. 2 panels in parallel is 2P. 2 panels in series is 2S. If you take 4 panels and put them in 2S2P then you have 2 pairs of panels in series and those two strings are put in parallel.

So think about the xSyP as a rectangle where the sides are the S and P.

The problem with 5 panels is you can only make a rectangle where one side has to be 1. So it's either 1S5P (written simply as 5P) or it's 5S1P (written simply as 5S).

So 1p - Optimum operating current 5.38 amps x 2 panels x 1.25 = 13.45 amps

1P is simply 5.38A. It doesn't matter if it's 2S1P, 3S1P, 4S1P, etc. And you only use the 1.25 factor when determining the fuse size, not the wire size.

 

[rmaddy]

10AWG is rated 30A, so you should be ok.

But it depends on the voltage and the wire length. For 12V you would only want to use 10AWG for 30A up to about 15 feet round trip. Otherwise the voltage drop starts to become an issue. With these panels you are talking about 22V so the 10AWG is good for about twice the length.

 

[rmaddy]

There were four panels in the kit and enough Y connectors to put them all in parallel. 4 y connectors. Mmm renogy said I could use a 5th panel? I’m only trying to do 5 100watt panels with ratings pictures in an earlier post.

You can use 5 panels with that charge controller but only if you wire the panels as 5P as we discussed earlier. 5S is the only other way to wire 5 panels but that charge controller can't handle the voltage of those 5 panels all in series.

 

[TEV]

This is a 3P, LOL I found a picture that have precisely your panels voltage and amps. The 4 sets of Y connectors are enough to connect all 5 in paralel, but you may need some 12AWG extensions from the panels to the Y connectors.

 

[Harmony5000]

So it looks like you have options...if you were only using 4 panels.
MPPT Voltage DC Maximum
75
Charging Current (Amps)
40
MPPT Voltage DC Minimum
14

Ok this wink makes sense to me now. Question, would you rather have 5 panels in parallel or 2s2p?

 

[Harmony5000]

You can use 5 panels with that charge controller but only if you wire the panels as 5P as we discussed earlier. 5S is the only other way to wire 5 panels but that charge controller can't handle the voltage of those 5 panels all in series.

This is a 3P, LOL I found a picture that have precisely your panels voltage and amps. The 4 sets of Y connectors are enough to connect all 5 in paralel, but you may need some 12AWG extensions from the panels to the Y connectors.

Ok so I do already have Y connectors and extensions does that work for 5 parallel or do I need the combiner box?

Would it be better to charge 200ah with 2s2p and return the 5th panel?

I actually do have room for a 6th panel but what I’m getting from this is my controller wouldn’t handle that.

Uhm an thanks for saving me I would have tried to wire them crazy (>^.^really appreciate it

 

[rmaddy]

A 200Ah 12V battery is 2560Wh. If you get 5 hours of solar in a good day then you need 512W to fully recharge the battery from 0% to 100%. Since you probably won't use more than 80% of the battery in a day you need about 410W. But since you rarely get 100% out of panels and many days you won't get 5 good hours of sun (in the winter you'll be lucky to get 2 hours of sun any only 40% out of the panels), using all 5 panels is a much better choice. 6 panels is even better.

Even though the controller is rated for 40A and 500W of panels, using 600W is actually OK. If your battery is near full (13.6V) then 40A allows for 540W. With 600W of panels you'll rarely get over 540W. The controller will max out at 40A charging at your battery's current voltage. Any panel wattage potential over that isn't used.

The key is to avoid ever going over the max PV input voltage which is based on the Voc of the panel arrangement, adjusted for the current temperature. So you could easily do 3S2P with 6 panels. No fuses, no combiner box, and no risk of too much voltage. You just need one pair of Y connectors, 6 panels, and 10AWG wire to go from the Y connectors to the charge controller.

FYI - 3S2P is done by taking 3 panels and putting them in series. Take the other 3 and put them in series. Now connect those two strings with the Y connectors.

 

[CamoGreg]

I would add an additional panel and do 3S2P.
Your SCC is capable of using this configuration. And no combiner fusing required.

Odd number of panels while sometimes possible, doesn't have much flexibility and not very practical.

 

[TEV]

Ok so I do already have Y connectors and extensions does that work for 5 parallel or do I need the combiner box?

You don't need a combiner box, you have everything you need, I would just do the five in parallel, and later, if you decide to over-panel your charge controller, you can add anther panel, and rewire ( you will need a tool to be able to unplug the connectors: https://www.amazon.com/BougeRV-Connectors-Assembly-Spanners-Wrench/dp/B089YRQBYX )

 

[Ozark Tinkering]

Ok this wink makes sense to me now. Question, would you rather have 5 panels in parallel or 2s2p?

2s2p

 

[TEV]

2s2p

Why? 5P is giving 25% more power, and make the system less affected by the shading. The OP has the proper connectors and the wires to do the 5P, so why go with only 4 panels?

 

[CamoGreg]

Why? 5P is giving 25% more power, and make the system less affected by the shading. The OP has the proper connectors and the wires to do the 5P, so why go with only 4 panels?

I don't see where he has everything he needs to do 5P.
I thought he only had 2 pair of MC4 branch connectors?

How will he combine 10 wires into 2 wires for input to the SCC?
And without fusing that many panels in parallel, isn't there a rare chance of fire should one panel short?


5 panels in parallel x Isc
5 x 5.86A = 29.3A

Combined Isc must be lower than Max Series Fuse rating: 15A

 

[TEV]

I don't see where he has everything he needs to do 5P.
I thought he only had 2 pair of MC4 branch connectors?

How will he combine 10 wires into 2 wires for input the the SCC?
And without fusing that many panels in parallel, isn't there a rare chance of fire should one panel short?


5 panels in parallel x Isc
5 x 5.86A = 29.3A

Combined Isc must be lower than Max Series Fuse rating: 15A

He bougt a kit with everything that he needs. Basically, the OP concern was that he saw that the wires on the panels are 12AWG, and was worried that when he connects the panels in parallel 12AWG wire will not be enough for the total current, not being aware that's not how it works, and that only the 10 AWG (that was sent with the kit) between the Y connectors and charge controller will see the total current.

 

[Harmony5000]

And without fusing that many panels in parallel, isn't there a rare chance of fire should one panel short?

5 panels in parallel x Isc
5 x 5.86A = 29.3A

Combined Isc must be lower than Max Series Fuse rating: 15A

He bougt a kit with everything that he needs. Basically, the OP concern was that he saw that the wires on the panels are 12AWG, and was worried that when he connects the panels in parallel 12AWG wire will not be enough for the total current, not being aware that's not how it works, and that only the 10 AWG (that was sent with the kit) between the Y connectors and charge controller will see the total current.

So you could easily do 3S2P with 6 panels. No fuses, no combiner box, and no risk of too much voltage. You just need one pair of Y connectors, 6 panels, and 10AWG wire to go from the Y connectors to the charge controller.

Hi all, ya so the video that @CamoGreg has posted is pretty much what the article I read was saying.

Short Circuit Current on each panel is 5.86a
Max Series Fuse Rating is 15a

Even though renogy said it’s ok to do 5 panels *I think* the guy making that determination only based that off of the mppt controller being rated at 520watts.

If this video and the article are correct it seems to me even if I only did 3 panels in parallel that would put me out of code -

5.86 short circuit current x 3 panels = 17.58

Which is above 15a max series fuse rating.

I do have all the connectors/extensions to set them up in 2p2s, 5p, and I could buy another panel (which I want to) and do 3s2p.

I’m not sure how to calculate 3s2p.. 3s amps stay the same so 5.86a (short circuit) then 2 of those in parallel = 11.72a?

So.... if I did 5p I would need fuses? 29.3a

If I did 3s2p I could just connect them as is??? 11.72a

Is the 3s2p calculation right?

Also is 3s2p and 2p3s the same thing? Anytime I say that I mean 3 panels in series and another 3 panels in series then both of those connected in parallel.

 

[rmaddy]

If I did 3s2p I could just connect them as is?

Look at the end of post #30 where I explain how to connect them in 3S2P.

I could buy another panel (which I want to) and do 2p3s.

You do not want to put them in 2P3S. Put them in 3S2P.

If this video and the article are correct it seems to me even if I only did 3 panels in parallel that would put me out of code -

5.86 short circuit current x 3 panels = 17.58

Which is above 15a max series fuse rating.

See:

Maximum Series Fuse Rating

Folks, I need some help understanding "maximum series fuse rating", and how this rating applies to my solar setup. I attached an excerpt from the spec sheet for my panels below. I will be putting three of these panels in series 3S1P (for now...may expand to 3S2P) going into an EPever Tracer...

diysolarforum.com

I’m not sure how to calculate 2p3s.. 3s amps stay the same so 5.86a (short circuit) then 2 of those in parallel = 11.72a?

Correct. 3S is 3 times the voltage but the same amps. 2P is 2 times the amps but the same voltage. So combined, 3S2P is 3 times the voltage and 2 times the amps of one panel.

 

[Harmony5000]

Look at the end of post #30 where I explain how to connect them in 3S2P.


You do not want to put them in 2P3S. Put them in 3S2P.

Correct. 3S is 3 times the voltage but the same amps. 2P is 2 times the amps but the same voltage. So combined, 3S2P is 3 times the voltage and 2 times the amps of one panel.

Ok ya- I get it for sure now! Gonna edit post above so there isn’t confusion

 

[Ozark Tinkering]

Ok ya- I get it for sure now! Gonna edit post above so there isn’t confusion

...if only it were that easy.