Need help fixing solar on trailer

[andrecampeau]

Hi

I have solar on my travel trailer that the trailer dealer tech installed for me but I don't think it's done properly.
I have 2-150 watt panels, 2-100 watt panels and a pmw controller. The panels were wired in parallel. From what I've read, if I have panels of different wattage, they should be wired in series, otherwise, my 150 watt panels will only give out 100 watts. Which also means I will need an mppt controller.
Is this correct?
What size mppt controller would I need?
Would a 45 amp do?

I was thinking of eventually changing to lithium ion batteries. Do I need a special mppt controller for that?

Thanks
Andre

[Mike90250]

we will need the Vmp and Imp specs off the stickers on the back of the panels.
If the Vmp is within a volt or so of each panel, you can wire all in parallel (with proper combiner fuses) and charge with PWM controller
To wire panels in SERIES -A-B-C-D- they all need to have the amps be very close, or the lowest amp panel, will throttle the outputs of the other panels, Imp value

Vmp = Voltage Max Power
Imp = Amps Max Power (yes, capitol i is the symbol for Amps)

[andrecampeau]

The panel are mounted with Dicor so it would be a big thing to remove.
The 100 watt panels (Renogy), I bought them on Amazon and they have the specs on the web site, Vmp: 18.9V, Imp: 5.29A.
The 150 watt panels (Coleman), I bought online at Costco and I can't find the proper specs. From what I found on the web, Vmp: 18V, Imp: 8.77A

Maybe I should remove the two 150 watt panels, sale them, and replace them with 2 or 3 Renogy 100 watt panels.

Thanks

[littleharbor]

Your Parallel configuration is correct for a PWM setup. Assuming you are running a 12 volt setup if you change over to a MPPT controller you can series wire the 100 watt panels and series wire the 150 watt panels then combine the two strings. The slight mismatch in voltage shouldn't be a problem. When series wiring panels you want to insure there isn't any shading issues ( AC shroud, crank up vent lids, etc.), which will seriously affect the output of the affected string.

[Sunking]

You really made big mistakes. You are using very expensive low voltage battery panels with a cheap PWM controller. You have no choice but to wire your panels all in parallel and throw 35% of you power away. Who ever put this together has no idea what they were doing.

You cannot use a MPPT controller with your panels. You should have used higher voltage grid tied panels. It would have only take 300 watts to equal your 500 watts. OK since you have a PWM controller with all your panels wired in parallel you only need a 25 amp controller. So out of 500 watts you only get 320 watts.

If I were you, I would throw away the 2-100 watt panels and buy a 25 amp MPPT controller. Wire the two 150 wat panels in series and you get the exact same 25 amps your 500 watt system generates.

Nah that is a lie, I would just buy a single 300 watt panel with a 25 amp MPPT controller. I would not waste my money on battery panels. You could have done this for 1/3 to 1/2 of what you paid.

[andrecampeau]

Would I be able to use one charge controller for the two 150 watt panels and another charge controller for the two 100 watt panels?

[littleharbor]

Do whatever you see fit but I think throwing away your ,already purchased panels and controller is a lame approach, Sorry Sunking but this guy is trying to get the best out of his current setup. If he were starting from scratch yeah but what he has can work fine and even better with adding only an MPPT controller.

[Mike90250]

Sunking, this needs to fit on a camper roof, and the panels are an afterthought after the other rooftop gear was installed.

And it may be that the small panels won't have much effect on recharging because of flat mounting and bad sun angle

[Sunking]

Do whatever you see fit but I think throwing away your ,already purchased panels and controller is a lame approach, Sorry Sunking but this guy is trying to get the best out of his current setup.

NP I get it. My bad.

OP all your battery panels are roughly the same Vmp but different Imp. What that means is you only have one wiring option available to you, all panels in parallel. As for charge controller any thing larger the a 30 amp PWM controller is a waste of money unless you intend to grow the system.

You need to understand going this route will make your listed power of 500 watts and turns it into 330 watts. That is the nature of the beast using PWM controllers with battery panels. If your panels wer at least matched up like say 4-100 watt panels you could wire them 2 x 2 and use a 40 amp MPPT charge controller. When you use a PWM controller you automatically loose a minimum 33% of your power.

What pisses me off more than anything is the person who installed this does not understand what he or she is doing, nor do they understand the technology. If they had understood they would know to use at least MPPT controllers with Battery Panels if there are space restraints. It takes a 300 watt PWM system to equal a 200 watt MPPT system. So in the end what has happened your Installer spent to much money and passed it on to you. That is not good biz practice.

That is what happens when goberment tries to pick winners and throws money at it. Every idiot comes out of the woodwork trying to get the free money while it last.

[andrecampeau]

I appreciate any help you guys are giving. I will let the technician know that his work was wrong but at the mean time, I just want to get the most I can from my system.
So would it help to change my PWM controller to an MPPT controller? Would I get a bit more power?
And like I mentioned, what if I treat my two sets of panels as two separate systems with two PWM controllers each going to the trailer's charge controller which in turn goes to the two 6V batteries which are in series to give 12V.
Thanks again.

[Guest]

I appreciate any help you guys are giving. I will let the technician know that his work was wrong but at the mean time, I just want to get the most I can from my system.
So would it help to change my PWM controller to an MPPT controller? Would I get a bit more power?
And like I mentioned, what if I treat my two sets of panels as two separate systems with two PWM controllers each going to the trailer's charge controller which in turn goes to the two 6V batteries which are in series to give 12V.
Thanks again.

Yes MPPT is better. Delivers more power than PWM. PWM are cheaper than MPPT. for sure.