Has anybody ever heard of any 12 volt type solar panels not being able to wire them in series? Not physically of course but technically? I have 4 Coleman 100 watt panels and nowhere on the box or on the enclosed manual does it say to only wire in parallel or not to wire in series! Talked with a Coleman customer support rep, tech I think, and was told they can ONLY be wired in parallel?? I have been all over the Internet and cannot find anywhere, where there is some explicit instructions on any panel that I have seen to only wire them in parallel.Now I am not looking for pros and cons over series vs. Parallel I am aware of all that. Just whether there are panels made that must be wired in parallel only? __________________

I am aware of all that...and that Coleman sells their name to anyone for anything. Therefore finding out anything about a “Coleman” panel manufacturered by the lowest bidder that week will be near impossible. Similar to the Garmin 660.

Panel needs bypass diodes to wire in series. Otherwise shade issues could burn out the panel.Call the tech back and see if it has a bypass diode. Or open the terminal box and see if they exist. Post a picture.

It's not the panels, it's the controller.The issue is the PWM controller for 12v panels can only handle a low Voc like maybe 46 volts. Each panel has a Voc of 22v, so two in series is 44 (at 25C and higher when it is cold out.)If you are using an MPPT controller, it will have a Voc limit more like 100, so your four 22s in series is 88 and could be done.I have three 100s and have used them in parallel and in series. Got same amps to battery either way. I got the Isc value of 6.2 amps per panel in full high sun, so I was getting 18.6 amps with my PWM controller, panels in parallel. With four you could get 25 amps, so be sure to have at least a 30 amp controller (needs margin for times when panels get more than rated amps) whether you have a PWM or MPPT controller.

It’s not the diodes I’m concerned about, most all have diodes to prevent back feeding the panels from the battery! My question was about whether anyone was aware of solar panels that could ONLY be wired in parallel.My knowledge about solar panels is that they could from all manufacturers and types I.e. 36 cell 72 cell be wired series, parallel or series/parallel.This is also not about charge controllers pwm or mppt.

I said the panels can be used in series no problem. I do it with those Coleman 100w jobs Can Tire gets from Sunforce.The advice you got not to put them in series is about the controller, not the panels as such.There are mixing limits to doing either unless the panels "match" closely enough in their volt/amp specs for which way they are put together, but you have four the same, so no worries.

Solar panel wiring | Good Sam Community

13 Replies

time2roll
Nomad
May 04, 2018
prairie camper wrote:
It’s not the diodes I’m concerned about, most all have diodes to prevent back feeding the panels from the battery.
Blocking diode is different from bypass diode. One is in series the other in parallel with the cells. Bypass diode allows power to pass by a shaded section and allowing series panels.
2oldman
Explorer II
May 04, 2018
prairie camper wrote:
Our panels are designed to go in parallel (positive to positive, negative to negative)
The components of the panels are not designed to go in series.
Every solar panel I've ever seen has a 600v rating, meaning a series installation should not exceed that. I just checked their website, but they do not offer that specification, nor do they say they must be connected in parallel.

Given that, I'd choose a different brand.
red31
Explorer
May 04, 2018
What the hell do ya expect from a resaler company that only carries cheap PWM controllers for charging 12v batteries.
prairie_camper
Explorer
May 04, 2018
2oldman wrote:
prairie camper wrote:
talked with a Coleman customer support rep, tech I think, and was told they can ONLY be wired in parallel??
It is amazing what supposedly technical people don't know about electric things, and that includes RV repair persons. You were more likely talking to a salesman.

No kidding, here is an email reply from them.

“From: "Michael Carpenter"
Date: May 3, 2018 at 12:35:02 CDT
To: "'Donald
Cc:
Subject: RE: Solar panels

Hello Donald, thank you for your message.

Our panels are designed to go in parallel (positive to positive, negative to
negative)
The components of the panels are not designed to go in series.

Best regards,
Michael Carpenter
Customer Service Technician
Sunforce Products Inc.
1-888-478-6435 ext. 121”

I asked for a technical reply as to why they can only wired in parallel, that is what I got.
prairie_camper
Explorer
May 04, 2018
BFL13 wrote:
My post last night at 8:03 on my display has that--I have been missing some other people's posts, so I wonder if you missed mine? If so, I will ask Forum Support if they know about these missing posts. They do have server issues once in a while.

Anyway, I have three 100w panels that I have put in series at times and in parallel at other times. On one panel I get 6.2 amps (same value as Isc) in full sun. Don't believe that 5.8a they put on the label, that is the Imp which does not apply with PWM.

I think I received all your posts, thanks.
2oldman
Explorer II
May 04, 2018
prairie camper wrote:
talked with a Coleman customer support rep, tech I think, and was told they can ONLY be wired in parallel??
It is amazing what supposedly technical people don't know about electric things, and that includes RV repair persons. You were more likely talking to a salesman.
BFL13
Explorer II
May 04, 2018
My post last night at 8:03 on my display has that--I have been missing some other people's posts, so I wonder if you missed mine? If so, I will ask Forum Support if they know about these missing posts. They do have server issues once in a while.

Anyway, I have three 100w panels that I have put in series at times and in parallel at other times. On one panel I get 6.2 amps (same value as Isc) in full sun. Don't believe that 5.8a they put on the label, that is the Imp which does not apply with PWM.
prairie_camper
Explorer
May 04, 2018
BFL13 wrote:
I said the panels can be used in series no problem. I do it with those Coleman 100w jobs Can Tire gets from Sunforce.

The advice you got not to put them in series is about the controller, not the panels as such.

There are mixing limits to doing either unless the panels "match" closely enough in their volt/amp specs for which way they are put together, but you have four the same, so no worries.

How many of those do you have in series and how do you like Them?
BFL13
Explorer II
May 04, 2018
I said the panels can be used in series no problem. I do it with those Coleman 100w jobs Can Tire gets from Sunforce.

The advice you got not to put them in series is about the controller, not the panels as such.

There are mixing limits to doing either unless the panels "match" closely enough in their volt/amp specs for which way they are put together, but you have four the same, so no worries.
prairie_camper
Explorer
May 04, 2018
It’s not the diodes I’m concerned about, most all have diodes to prevent back feeding the panels from the battery! My question was about whether anyone was aware of solar panels that could ONLY be wired in parallel.

My knowledge about solar panels is that they could from all manufacturers and types I.e. 36 cell 72 cell be wired series, parallel or series/parallel.

This is also not about charge controllers pwm or mppt.

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Solar panel wiring

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