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How do I connect 5 solar panels?

Santa

Santa

.
Joined
Nov 10, 2019
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I am going to be doing a slightly modified version of Will's blueprint. https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html

I have (4) 100 watt polycrystalline panels, and (1) 100 watt monocrystalline suitcase panel. The specs on both types are very close to being the same. I want to have the option of moving the suitcase panel in and out of a vehicle for sun, so stealth can be achieved when necessary. Since the MC4 Y branch (1 to 4 parallel connector) is only for 4 panels, how would I connect the 5th one? Thank you for your help.
 
Santa said:
Since the MC4 Y branch (1 to 4 parallel connector) is only for 4 panels, how would I connect the 5th one?
Click to expand...
You can add a MC4 Y branch (1 to 2 parallel connector) to your 1 to 4 connector when you want to add your 5th panel. You could actually add this 1 to 2 connector anywhere between the panel(s) and your SCC.
 
MisterSandals said:
You can add a MC4 Y branch (1 to 2 parallel connector) to your 1 to 4 connector when you want to add your 5th panel. You could actually add this 1 to 2 connector anywhere between the panel(s) and your SCC.
Click to expand...
Thank you! Some things are obvious to some people, lol. ;-p That's why brainstorming on the forum is so great!
 
MisterSandals said:
You can add a MC4 Y branch (1 to 2 parallel connector) to your 1 to 4 connector when you want to add your 5th panel. You could actually add this 1 to 2 connector anywhere between the panel(s) and your SCC.
Click to expand...
BTW, wouldn't there be a drop in voltage to have 2 branch connectors?
 
Santa said:
BTW, wouldn't there be a drop in voltage to have 2 branch connectors?
Click to expand...
Ideally, the fewer connections the better. But if they are good connectors, not a big problem with connecting them(the connectors) in series. A tiny voltage drop across a connection is not a problem unless there is so much current that there is then enough heat across that connection that the heating is a problem.
 
Santa said:
Thanks Will! I searched for 5...but didn't see any. I just didn't ask the right search question! Is there going to be power loss from the extra connection that's not being used? (I can't add any more panels bc of the charge controller limits.)
Click to expand...
Just keep water out of the unused connections. No loss from an unused connection.
 
I would consider the location of where you would put the 1 to 6 connector and see if that is a convenient location to hook up your carry out panel. Since its all parallel, you can add your 5th (carry out) panel connection anywhere. I would see if there is a convenient place to add (the earlier discussed) 1 to 2 connector that does not require you to get up on the roof.

Otherwise the 1 to 6 is a great idea. Plug up the unused ports to keep them clean.
 
Dust caps for the unused one. I have 4 panels in parallel and I doubled up on branch connectors to make that happen-no issues.

Screenshot_20191222-114331_Amazon Shopping.jpg
 
FYI, Combining panels in parrallel that way can be dangerous when the panel count goes over 3 or so. The reason is if any panel develops a problem, it can be back-fed the combined current from all the other parrallel panels, which can have more total current than the wire and panel can handle, posing a fire risk. That's why combiner boxes always individually fuse or circuit breaker each string.
 
PHoganDive said:
FYI, Combining panels in parrallel that way can be dangerous when the panel count goes over 3 or so. The reason is if any panel develops a problem, it can be back-fed the combined current from all the other parrallel panels, which can have more total current than the wire and panel can handle, posing a fire risk. That's why combiner boxes always individually fuse or circuit breaker each string.
Click to expand...

Wouldn't the panels' blocking diodes protect against this?
 
PHoganDive said:
FYI, Combining panels in parrallel that way can be dangerous when the panel count goes over 3 or so. The reason is if any panel develops a problem, it can be back-fed the combined current from all the other parrallel panels, which can have more total current than the wire and panel can handle, posing a fire risk. That's why combiner boxes always individually fuse or circuit breaker each string.
Click to expand...
Will said 4 panels would work. I was just thinking of throwing the suitcase in, since I already had it and it would be slightly under the controller's capability. If I am wrong, please let me know.
 
New Mexico Will said:
Wouldn't the panels' blocking diodes protect against this?
Click to expand...
As long as they're working properly, but I don't like betting on electronic devices proper operation for fire prevention, a fuse or circuit breaker is much safer. If you've ever had a personal encounter with a fire, you'd take every precaution as well.
 
PHoganDive said:
The reason is if any panel develops a problem, it can be back-fed the combined current from all the other parrallel panels
Click to expand...
I will trust PHoganDive with regards to the back-fed issue.

But the current (amps) should be addressed and we have not done that for Santa. With 5 panels in parallel, which means the amps are added for all panels, it will require paying attention to the wire sizes!
What are the panel amps and how long will the longest point be from any panel and the SCC? And what wire gauge is Santa using?

Attached is the guide i use - i think one of these should be a sticky on this site somewhere.
 

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MisterSandals said:
I will trust PHoganDive with regards to the back-fed issue.

But the current (amps) should be addressed and we have not done that for Santa. With 5 panels in parallel, which means the amps are added for all panels, it will require paying attention to the wire sizes!
What are the panel amps and how long will the longest point be from any panel and the SCC? And what wire gauge is Santa using?

Attached is the guide i use - i think one of these should be a sticky on this site somewhere.
Click to expand...
I was planning on using 10 Ga wire for the panels.
Specs for the (4) panels are:
100W
18.2 Vmp volts 18.2V x 5.5amps=100.1 watts (x 4 = 400.4 volts)
5.50Amps- Imp
Short circuit Isc 5.7A
Open circuit voltage Voc 21.4
Max system voltage 600 VDC
Fire rating class c

And for the suitcase:
100W
18 Vmp
2.78x2= 5.56 (amp) Imp=100.08watts
short circuit current Isc 3.24 A (6.48A total suitcase)
OPEN CIRCUIT Voc 21.83 v
Max system VDC 1000
 
and I am putting them in a van, down by the river, LOL.
 
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