# Optimal panel arrangement

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Solar Expert Posts: 35
What would be the optimal arrangement of my solar panels into the controller?

I will be in an average ambient of 90F at a latitude of 10degrees (west africa). The temps can get as high as 110-115.

I have (4) 123W panels going into a BZ MPPT500 controller outputting into a 12V 1260Ah gel battery bank.

BZ MPPT500 controller
• VOCmax=100
• Pmax = 500 (they say it can go up to 1KW)
• Imax charge = 45

Each panel is a sharp ND-123UJF
• VMP 17.2
• IMP 7.15
• VOC 21.8
• ISC 7.99

3 options I see to connect the 4 panels are (no derating):

4 panels in series. Controller input would be:
• V=87.2
• I=8
• P=492
Low current, smaller wires. Running at the top end of my controller spec for power and voltage (although they says it's derated at least 50%). I'll run above the charging voltage most here.

4 panels in parallel. Controller input would be:
• V=21.8V
• I=32
• P=492
Alot of I so need large wire size into controller or I'll have a big voltage drop. In our temps and bad days, we will operate more often below charging point so the software will have to boost more often (is this a bad thing?)

2 strings of 2, each string in parallel with each other Controller input would be:
• V=43.6
• I=16
• P=492
Middle of the road but still higher current so larger wire than series connected. Should stay above charging voltage more often than parallel config.

Is my math right? Please comment on the logic for each system.

What would be the optimal arrangement for these panels into the controller? What factors are most important??

There are sooooooooo many variables to consider.

Kim

• Solar Expert Posts: 1,989 ✭✭✭
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Re: Optimal panel arrangement

Kim, the BZ charge controller is worthless ...

For your climate, I would suggest all 4 panels in one series string to a quality Mppt charge controller.

The MorningStar TriStar Mppt 45 amp would be ideal as its lower cost, or the Xantrex XW-Mppt, Outback FM series or the TriStar Mppt 60 amp would all work well for your 4 panels.

The only configuration for the BZ, your be 4 panels in parallel, as the BZ is miserable at down converting, at least in this configuration you would get some of the harvest from the panels
• Solar Expert Posts: 35
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Re: Optimal panel arrangement

I can believe that it may be worthless. Is there some info out there that I can show to the group that it does not down covert well and a better controller is needed?

I am investigating this solar system that is not working well at all. It was designed maybe 8 years ago and has been modified by another guy who I don't feel is very good with solar. Hence, ALL MY QUESTIONS!!

I want to get the system in good working order but I am tryng to understand all the different components and how well they work. A group is going back out to Guinea to work on the system and my goal is to have a complete understanding of the system and how to make it work at it's optimum.

Any help would be greatly appreciated.

Kim
• Solar Expert Posts: 386 ✭✭✭
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Re: Optimal panel arrangement
I have (4) 123W panels going into a BZ MPPT500 controller outputting into a 12V 1260Ah gel battery bank.

A big concern for me is that is a very small array for a 1260 amp battery system. You should probably be supplying somewhere between 63 and 120 amps of solar at 12 volts just to properly support this battery bank. It seems that you would need about 6 more panels, split the battery bank and wire it for 24 volts, then an 80 amp MPPT charger could handle the charging current. I don't know if your requirements are for 12 volts or you use an AC inverter?
• Solar Expert Posts: 9,583 ✭✭✭✭✭
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Re: Optimal panel arrangement
momofgcm wrote: »
I can believe that it may be worthless. Is there some info out there ....

Yes, go to google and paste "BZ" site:wind-sun.com
this will bring up all articles at this forum about BZ
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Solar Expert Posts: 35
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Re: Optimal panel arrangement

I just found out tonight that the setup only has FOUR batteries. That makes a big difference. I have to go back tonight and recalculate everything.

The system will have a 12V fridge then ac loads like lights and such. This is basically a reverse engineered system! Sad.

Off to look at BZ. He just bought the controller so I don't know how much luck I'll have changing it. But, I'm definitely going to look into it.

Kim
• Registered Users Posts: 8
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Re: Optimal panel arrangement

Kim, how did this story ultimately unfold? Have you made any decisions?