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4 rooftop solar panel connections installed around around AC

wuli959

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Jan 27, 2022
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I am adding 4 solar panels to the top of my truck camper which has limited roof space.
I have two narrow long solar panels to run up either side of the central mounted AC unit and two other panels to mount to the front and rear of the AC.
All panels are from the same manufacturer and have the same fundamental output specs.
The narrow/long panels will tilt slightly to the outboard edges.
The front panel will tilt slight forward to the front of the unit.
The rear panel will for the most part be level.
Their could be minor shading on the panels from the AC unit dependent on the angle of sunlight.

What would be the best way to connect these panels so that they would end in a singular MPPT controller?

thank-you
 
I am adding 4 solar panels to the top of my truck camper which has limited roof space.
I have two narrow long solar panels to run up either side of the central mounted AC unit and two other panels to mount to the front and rear of the AC.
All panels are from the same manufacturer and have the same fundamental output specs.
The narrow/long panels will tilt slightly to the outboard edges.
The front panel will tilt slight forward to the front of the unit.
The rear panel will for the most part be level.
Their could be minor shading on the panels from the AC unit dependent on the angle of sunlight.

What would be the best way to connect these panels so that they would end in a singular MPPT controller?

thank-you
Connect in parallel. You will need to have a panel voltage about 5V higher than your system voltage.

I saw this problem on my truck camper and built a tilt mechanism so the panels on each side of the roof ac could be non shaded and if I was to take a trip in winter to the southern US.

I'm currently in the process of installing a mini split and will remove the roof ac. This will allow 2 more 100w panels to be installed on the tilt mechanism. No more shading issues either.

I've seen some people install an elevated roof rack to prevent shading. This also allowed some storage under the rack. It does raise the height of the unit however, most rigs are tall enough already.
 
Here is a thread that shows how shading effects my panels.


You do want to go in parallel as much as possible. Depending on voltage loss all 4 in parallel, but if you can‘t get the mentioned 6 volts because of a lower VOC, the. 2S2P.

The AC shading you mentioned effected my build. Since I made that thread, I went with a 24 volt system and the flexible panels needed 2 in series to make charging voltage. I also added more and ended up with 2S3P. I chose what panels to put in series so they’d be shaded less throughout the day and park east west.

At times, I lose a bit of energy for shading, but it’s as good as it’ll get. IMO, with a 35’ fifth wheel and two 15k BTU ACs, a mini split is not practical.
 
Thanks for the insights.
So a bit more info. I have a simple system. 12 volt with a 206 amp LI Ion battery. Charging at 14.6 v
Utilizing a RENOLOGY 50 DC/MPPT controller
The specs for each of the panels are below but max power voltage 20.5 Vmp & max power current 4.6 amps
I was considering pairing two in series and then connecting the two pairs in parallel. But couldn’t figure out which sets to pair.
Connecting them all in parallel simplifies that decision But not sure if the panels have enough power to effectively charge hooked up that way.5EF962C8-7940-4CEE-90FA-A89F8516724F.jpeg
 
I don't see an optimal configuration other than parallel. You can't predict how the camper is going to be parked relative to the sun and with panels on all four sides, you're boxed into the parallel configuration.

I don't think you can put those panels in series at all. You completely screwed yourself with that Renogy DC-DC/MPPT device. The Max PV Input Voltage is 25 volts and your panels are right under that limit. In cold weather they'll likely go over that limit.
 
Thanks for the insights.
So a bit more info. I have a simple system. 12 volt with a 206 amp LI Ion battery. Charging at 14.6 v
Utilizing a RENOLOGY 50 DC/MPPT controller
The specs for each of the panels are below but max power voltage 20.5 Vmp & max power current 4.6 amps
I was considering pairing two in series and then connecting the two pairs in parallel. But couldn’t figure out which sets to pair.
Connecting them all in parallel simplifies that decision But not sure if the panels have enough power to effectively charge hooked up that way.View attachment 93173
with the panels at 20 volts and 4P, i don’t see you having problems.

I had a portable ground array four panels in parallel at 18 volts that charged a 12 volt battery pack. That was with a 40’ run of 6 awg wire after the combiner to the SCC. I think the voltage will be enough with your panels being 2 volts more.

Use a dc voltage loss calculator to see if it takes you too low.

I used to think there was a 30 amp limitation on mc4 connectors, but the ones @Paul_R listed are good to 50 amps. To get 50 amps with 4 solar panels combined, it would have to be a pretty big wattage panel.

Just make sure the wire out of the branch connectors to the SCC is rated for the max amperage your panels will deliver.
 
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