Add to factory solar or replace

[dcl]

Hi All,

I have a GD 22MLE trailer that comes with a 165w panel and small scc.. Very cheap battery installed by dealer. I'm planning to upgrade, adding 3 200w panels connected to a new scc and Li battery.

I was going to pull out the factory panel but now I'm wondering if there's benefit in keeping it and connecting its scc to the same battery as the new system. Seems like extra power for little money. I'd have to drill a new hole in the roof for the new string of panels but wouldn't have to deal with removing the original stuff on the roof, a wash hopefully.

What would you guys do?

 

[dcg9381]

I've got a Wolf Creek (Northwest manufacturing) truck camper. It comes with a 12V 45 watt panel and a 10A controller. I didn't want to get into rewiring the camper, so I looked up the controller specs and was able to add a 200 watt (22V) panel. I did not tie in the additional 45 watt panel (parallel).

Depending on your camper type, your roof material may be very thin. You also have to deal with the rubber membrane. My roof was not ply or osb, just like very thin material. You either have to find the studs or install a type of connector that expands. 3M also makes a tape that reviews very well in terms of holding panels to the roof if you don't want to do penetrations.

 

[MisterSandals]

165w panel and small scc.. Very cheap battery installed by dealer. I'm planning to upgrade, adding 3 200w panels connected to a new scc and Li battery.

If you have room for 4 panels and the specs match close enough to make a 2S2P or other desirable array, then i'd strongly consider combining. But with enough room and trying to do it right the first time, i'd likely just add 4 identical panels, even if it meant removing the existing 165W panel.

So it mostly depends on info that only you know at this point.

 

[dcl]

Depending on your camper type, your roof material may be very thin. You also have to deal with the rubber membrane. My roof was not ply or osb, just like very thin material. You either have to find the studs or install a type of connector

I've got a Wolf Creek (Northwest manufacturing) truck camper. It comes with a 12V 45 watt panel and a 10A controller. I didn't want to get into rewiring the camper, so I looked up the controller specs and was able to add a 200 watt (22V) panel. I did not tie in the additional 45 watt panel (parallel).

Depending on your camper type, your roof material may be very thin. You also have to deal with the rubber membrane. My roof was not ply or osb, just like very thin material. You either have to find the studs or install a type of connector that expands. 3M also makes a tape that reviews very well in terms of holding panels to the roof if you don't want to do penetrations.

Haven't decided on the brackets yet but they'll be screwed and/or anchor bolted in. It's thick enough to walk on, though it does flex, so expecting the panels to stay. It's a TPO roof so not planning on taping.

Sounds like you're running 2 separate solar systems then. Though about that but figured I'd be better off with one battery bank covering everything.

 

[dcl]

If you have room for 4 panels and the specs match close enough to make a 2S2P or other desirable array, then i'd strongly consider combining. But with enough room and trying to do it right the first time, i'd likely just add 4 identical panels, even if it meant removing the existing 165W panel.

So it mostly depends on info that only you know at this point.

My comptroller has put a cap on the cost of this project and I'm already over so won't be able to buy a 4th matching panel. Not sure how to tell if the 2 different types of panels are close enough to mix in 2S2P. Can you tell from the specs

// The factoy panel specs are

Maximum power (Pmax) 165W
Max Power Voltage (Vmp) 18.72V
Max Power Current (Imp) 8.82A
Open Circuit Voltage (Voc) 23.12V
Short Circuit Current 9.49A
Cell Efficiency 20%
Maximum System Voltage 600V DC
Power tolerance ± 3%
Series Fuse Rating 15A

// The new ones are

If I can't combine in 2S2P or with parallel charge controllers then I'll pull the factory panel.

 

[MisterSandals]

My comptroller has put a cap on the cost of this project

What SCC do you have? Need the specs of this to see if your panels can be configured in a good way. Heck, i'm not sure how your 3 200W panels need to be configured. Its not impossible to add the 4th.

 

[dcl]

Sure. The factory scc is the furrion FSCC30PW-BL. No idea who makes it. It's a 50/25, lithium capable.

Battery System Voltage 12V/24V
Max. PV Power (Pmax) 300W
Max. PV open circuit
Voltage (VOC) 70V
MPPT efficiency ≥99%
ECO mode draw current <1mA
Min. Battery Voltage for Charging 3V
Max. MPPT Charging Current 25A
Charging Mode (three charging stage)
Bulk voltage charging,
Absorption charging and Float
charging
https://www.manualslib.com/manual/2018087/Furrion-Furrionnet-Zero-Fscc30pw-Bl.html

If the scc is a nogo, I'd look at the victron 75/15 for this 1 panel. Again, only if it makes sense to incorporate it.

If adding a 4th matching panel, I assume in 2S2P (800w) I'd have to move to a bigger solar charger I think which is a significant up charge plus the cost of the panel.

 

[MisterSandals]

These SCCs are too small.

The 3x 200W panels need: 600W / 14V charging = 43A SCC

It's a 50/25, lithium capable.

Not sure what this means? 50V input voltage, charges at 25A? But the specs say max input voltage is 70Voc so who knows?

For a solution, i would consider combining your existing 100W panel and a 200W panel in series for your existing 25A SCC.
300W / 14V charging = 21.4A

Then get another SCC, like a Victron 100/30 for your other 2x 200W panels in series.
400W / 14V charging = 28.6A

 

[dcl]

Thanks mister Sandals. To clarify, the existing panel is 165w so combined with one of the 200W panels looks like it'll be a little high or right on the edge (365W / 14V = 26A) fpr the original CC as it tops out at 25A. Are the specs on the 2 different panels close enough to combine in 1 string?

I was planning on the Vic 100/50 mppt for the just the 3 new panels series wired which I though would work (73V and 43). I assume I'd have to go to a bigger CC if adding a 4th panel in series or in 2S2P config (48.6V - 57A).

I think I'll be replacing the stock CC either way, no point risking a weak link in the system.

 

[MisterSandals]

165w so combined with one of the 200W panels looks like it'll be a little high or right on the edge (365W / 14V = 26A) fpr the original CC as it tops out at 25A.

Thats fine, the 25A number is the max that the SCC will pull from the panels. This is commonly called "over paneling" and is a good strategy to increase production in low light conditions.

Are the specs on the 2 different panels close enough to combine in 1 string?

Plenty close. If combining in series, the volts add and the amps are clipped to the lower of the 2 panels.

(18.72Vmp + 20.4Vmp) x 8.82A = 345W ... on paper anyway. Thats not too shabby for 2 random panels.

 

[MisterSandals]

(18.72Vmp + 20.4Vmp) x 8.82A = 345W ... on paper anyway. Thats not too shabby for 2 random panels.

Lets go a step further making this 2S2P with your existing 165W and 3 new 200W

First array is 39.12V with 8.82A
Second array would be 40.8V at 9.8A

Combine these in parallel with a simple MC4 Y cable, create an 2S2P array of 39.12V at 18.62A = 728.4W (again, this is really pretty good)

So 728W / 14V charging = 52A
A Victron 100/50 would be an excellent solution (make sure you get the smart version with bluetooth, its amazing)

 

[12VoltInstalls]

planning to upgrade, adding 3 200w panels connected to a new scc and Li battery

Never buy a quantity of panels that is a prime number. That limits config and on a camper you need less limiting factors: there’s enough already.

Sell the oddball panel and buy a 4th

 

[dcl]

Never buy a quantity of panels that is a prime number. That limits config and on a camper you need less limiting factors: there’s enough already.

Sell the oddball panel and buy a 4th

Now you tell me Seems like good advice.

 

[dcl]

Lets go a step further making this 2S2P with your existing 165W and 3 new 200W

First array is 39.12V with 8.82A
Second array would be 40.8V at 9.8A

Combine these in parallel with a simple MC4 Y cable, create an 2S2P array of 39.12V at 18.62A = 728.4W (again, this is really pretty good)

So 728W / 14V charging = 52A
A Victron 100/50 would be an excellent solution (make sure you get the smart version with bluetooth, its amazing)

Looks like you're using the Vmp / Imp values in the calculations which makes it more 100/50 friendly than using the Voc / Isc like I was doing. I thought using the Voc / Isc was the right way to account for worst case scenario on a faulty panel. Assuming I have that wrong it's not the first time. Can you elaborate a bit so I better understand.

 

[MisterSandals]

The Vmp and Imp values are the working values. If you're looking at output, use these values.
The Voc is the no load voltage and is used (along with temp compensation) for staying within the SCC max input voltage. In the morning, when its cold and sun hits your panels (MPPT not fired up yet so no load) the voltage can spike. If it exceeds your SCCs max input voltage, it will likely let the magic smoke out.
The Isc is used for calculating wiring and fusing requirements as its the worst case scenario (dead short).

 

[dcg9381]

Haven't decided on the brackets yet but they'll be screwed and/or anchor bolted in. It's thick enough to walk on, though it does flex, so expecting the panels to stay. It's a TPO roof so not planning on taping.

Sounds like you're running 2 separate solar systems then. Though about that but figured I'd be better off with one battery bank covering everything.

Most of the larger RV roofs (if they have a latter) are OSB. It's thick enough to be used for hold down.
I have a Wolf Creek (same Manufacturer as Artic Fox) truck camper. You can walk on it, but it's maybe 1/8th thick, the rest is sandwich foam and frame.

I'd recommend Eternbond over any hole / at the footer you put in a rubber roof. The TPO does not like being drilled into with a standard bit.

I use "well nuts" to hold thing onto either roof type.

 

[RoadTurtle]

Been there, done that!!!

REPLACE!!!!

I went through the upgrade and it worked ok, but didn't even come close to meeting my expectations. I took a huge step back and realistically set my expectations and planned out the system. This literally took months of researching and asking what seemed like an endless and infinite number questions.

I was fighting a lot of space issues, both on the roof and in compartments for the equipment on my smaller and very tall fifth wheel.
.
The real game changer was the Multiplus II 2x. I'm escatic with how well my system operates given all the constraints I had to deal with.

 

[dcl]

Most of the larger RV roofs (if they have a latter) are OSB. It's thick enough to be used for hold down.
I have a Wolf Creek (same Manufacturer as Artic Fox) truck camper. You can walk on it, but it's maybe 1/8th thick, the rest is sandwich foam and frame.

I'd recommend Eternbond over any hole / at the footer you put in a rubber roof. The TPO does not like being drilled into with a standard bit.

I use "well nuts" to hold thing onto either roof type.

View attachment 141597

I do have a ladder and believe it to be OSB roof. Can't believe I never heard of well nuts, I'll check them out. My roof will be redone by RV Armor after panel installation so no need for eterna bond tape this time around.

 

[PlanetExcellent]

Our trailer came with 1 80 watt panel and a small PWM controller. I decided to leave it in place, and add 2 210 watt panels with their own controller. It works fine; you can have multiple charge controllers connected to your DC bus bar.