Purchased six (6) SanTan 250Watt PV Panels - Best Config Given My Charge Controller?

TedH · Jun 24, 2020

I have an AIMS 60amp Solar Charge Controller (SCC60-100A). I am charging two, 24v LifePO4 batteries (I am assembling the two batteries using eight, CALB 3.2v, 100ah cells). Fresh new cells

Parameters on the AIMS Solar Charge Controller:
PV operating voltage - 15-155Vdc@12V, 15-155Vdc@24V
Max. PV open circuit voltage - 155Vdc
Rated PV input - 24V 1700W

SanTan 250Watt PV Panels (SS270P-72):
Maximum Power - 270W
Open - Circuit Voltage - 44.4V
Voltage at Pmax - 35.5V
Short - Circuit Current - 8.25A
Current at Pmax - 7.60A
Max System Voltage - 600V
Fuse Rating - 15A

I have an older 3000W AIMS Pure Sine Wave Inverter/Solar Charger (I am not using the Solar Charger feature as it is not adjustable for LifePO4). 24Vdc in

What is the optimal serial, parallel config to string the panels to support my 24v charging, battery and inverter?

mopat · Jun 24, 2020

TedH said:
I have an AIMS 60amp Solar Charge Controller (SCC60-100A). I am charging two, 24v LifePO4 batteries (I am assembling the two batteries using eight, CALB 3.2v, 100ah cells). Fresh new cells

Parameters on the AIMS Solar Charge Controller:
PV operating voltage - 15-155Vdc@12V, 15-155Vdc@24V
Max. PV open circuit voltage - 155Vdc
Rated PV input - 24V 1700W

SanTan 250Watt PV Panels (SS270P-72):
Maximum Power - 270W
Open - Circuit Voltage - 44.4V
Voltage at Pmax - 35.5V
Short - Circuit Current - 8.25A
Current at Pmax - 7.60A
Max System Voltage - 600V
Fuse Rating - 15A

I have an older 3000W AIMS Pure Sine Wave Inverter/Solar Charger (I am not using the Solar Charger feature as it is not adjustable for LifePO4). 24Vdc in

What is the optimal serial, parallel config to string the panels to support my 24v charging, battery and inverter?

6 panels, 3 in series, paralleled with 3 more

1700 watts / 270 watts = 6.29 panels; so 6
155Vdc / 44.4V = 3.49; so 3 panels in series (133.2Vdc)
3+3 =6

mandrews44 · Jun 24, 2020

When configuring PV to SCC, you want to divide the max pv by open circuit voltage of the cells to find your MAX # of panels you can put in Series. In this case, you can use 3 Series max. The more panels you have in series, the less transmission loss you will have. The more you have in series, the more your system is sensistive to shadows, so there is a tradeoff. Without knowing your installation, making a real suggestion is impossible.

As long as you have no shadows, I would recommend 3S2P to keep the voltage the highest and current the lowest with the lowest power line loss.

80% Battery Capacity: 3840 watts
Daily Solar Capacity: 1500w * (yearly average solar hours) (8,250 for me (5.5 hours avg).
Required daily sun to fully charge batteries: ~2.5 hours.

TedH · Jun 24, 2020

Thanks. So, I will have two sets: three panels in series. 6 total panels.

The panels are flat on the roof with direct sun until after 2pm when the sun begins to be filtered by tree canopy.

Purchased six (6) SanTan 250Watt PV Panels - Best Config Given My Charge Controller?

TedH

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mopat

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mandrews44

Solar Enthusiast

TedH

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