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Panel and Wiring Setup for 40' Catamaran

El Guapo

New Member
Joined
Jan 7, 2021
Messages
13
Good afternoon everyone,

We recently (last week) upgraded our 680ah of AGM to 780ah of LifePo4 and are now turning our attention to our panels as they don't seem to be keeping up/charging sufficiently.

The existing panel configuration is:
  • 2 - 165watt panels
  • 4 - 100 watt panels
I'm considering upgrading the panels by replacing the 4 - 100watt panels with 4 - 380 watt LG NeON 2 panels and keeping the 2 - 165watt panels.

I have an existing FlexMax 80 MPPT and it is new, with less than 1 yr of operations. If I didn't purchase an additional MPPT, I assume I would be forced to config as follows but am concerned that the panels will exceed MPPT ratings (I believe I have the option of wiring in parallel and then series but don't know how stepping up voltage at pv array effects 12v operating system):
1638217438646.png
If I elect to purchase an additional FlexMax 80, I could split the panels as follows, but I don't know if the added cost is worth the output received. (to be clear, I'm okay with spending money to get this setup optimized. I'm lacking the technical expertise.)
1638217566508.png

Any recommendations for research or other areas I can educate myself on the best way to configure our system, it would be greatly appreciated.

As a side note, given the limitations of wind and hydro power generation, I've concluded that it would be best to size the pv array so that I can primarily depend on that system for charging and fall back on the Balmar on my stbd engine if we run into multiple overcast days or for running energy hogs such as the water maker, A/C, water heater, etc.

Thank you in advance and I'm happy to provide any additional details needed.

Kindly,

Kevin Fort
 
If you can avoid it, you shouldn't mix different panels on the same controller. Especially if they are very different. I would use 3 controllers. I would put the 2 165W panels on one controller, and 2 380W panels on each of the other 2. I would likely connect the panels in series. The panels are more efficient in series and the controller will step the voltage down to where it belongs to charge the batteries.

It isn't clear from the drawings how you have the MC-614 and duo charge configured. Is the MC-614 charging the LFP, and the duo-charge between the LFP and AGM charging the AGM?
 
Agree. Don't try to mix the panels. Use one SCC for the 2 165W panels. 330W / 12V = 27.5A. Get a small SCC for those two panels. Put them in series to up the voltage. A small SCC that can handle up to 75Voc and outputs 25A would be plenty for those two panels.

For the 4 380W panels, all 4 is too much for your FlexMax 80. Its specs state a max of 1250W but a recommended max of 1000W. 4 x 380W = 1520W. At 12V that's up to 125A. Even at 80% that's 100A. So the FlexMax 80 will waste a lot of potential solar with all 4 panels.

You could try to find an MPPT that can handle 1500W or you could split the 4 380W panels into 2 pairs, each with their own MPPT. Then you have 760W each. At 12V that's 63A. So an MPPT that supports 60A output would be a good choice. You could keep your current FlexMax 80 for one pair and buy another that outputs 60A for the other pair. The Voc on 380W panels is likely in the high 40V range. If you put the panels in series you'll be close to 100V. It wouldn't take much in cooler temps to go over 100V so you would want an MPPT that can handle at least 120V input voltage. There is a FlexMax 60 that would work well here.
 
If you can avoid it, you shouldn't mix different panels on the same controller. Especially if they are very different. I would use 3 controllers. I would put the 2 165W panels on one controller, and 2 380W panels on each of the other 2. I would likely connect the panels in series. The panels are more efficient in series and the controller will step the voltage down to where it belongs to charge the batteries.

It isn't clear from the drawings how you have the MC-614 and duo charge configured. Is the MC-614 charging the LFP, and the duo-charge between the LFP and AGM charging the AGM?
Yes, sorry. The duo-charge essentially monitors the LFP and once fully charged will overflow into the starting AGM on that engine.
 
If you can avoid it, you shouldn't mix different panels on the same controller. Especially if they are very different. I would use 3 controllers. I would put the 2 165W panels on one controller, and 2 380W panels on each of the other 2. I would likely connect the panels in series. The panels are more efficient in series and the controller will step the voltage down to where it belongs to charge the batteries.

It isn't clear from the drawings how you have the MC-614 and duo charge configured. Is the MC-614 charging the LFP, and the duo-charge between the LFP and AGM charging the AGM?
This info is really helpful. My pressing questions have been answered. I appreciate your help!
 
Agree. Don't try to mix the panels. Use one SCC for the 2 165W panels. 330W / 12V = 27.5A. Get a small SCC for those two panels. Put them in series to up the voltage. A small SCC that can handle up to 75Voc and outputs 25A would be plenty for those two panels.

For the 4 380W panels, all 4 is too much for your FlexMax 80. Its specs state a max of 1250W but a recommended max of 1000W. 4 x 380W = 1520W. At 12V that's up to 125A. Even at 80% that's 100A. So the FlexMax 80 will waste a lot of potential solar with all 4 panels.

You could try to find an MPPT that can handle 1500W or you could split the 4 380W panels into 2 pairs, each with their own MPPT. Then you have 760W each. At 12V that's 63A. So an MPPT that supports 60A output would be a good choice. You could keep your current FlexMax 80 for one pair and buy another that outputs 60A for the other pair. The Voc on 380W panels is likely in the high 40V range. If you put the panels in series you'll be close to 100V. It wouldn't take much in cooler temps to go over 100V so you would want an MPPT that can handle at least 120V input voltage. There is a FlexMax 60 that would work well here.
Thank you for taking the time to respond. This is very helpful. I appreciate your effort(s).
 
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