PV system producing much less peak output

[Dallascowboy]

I have a 3 panel PV system with panels rated at 250W and 36V each connected to a MPPT charge controller and 2000W inverter. The solar array is panels connected in parallel. The maximum output I have been able to measure so far is 350W. I have noticed that when it is under a connected load (such as a small portable air conditioner), the voltage drops to like 14V (at about 24 Amps). Not sure what is going on and how I can get as close as possible to 750W at 36V.

I do not expect 100% efficiency by any means, but currently I am at less than 50% efficiency. The data shared here is under full sun exposure. Any help or suggestions to troubleshoot will be much appreciated.

 

[Mattb4]

You mention panels, SCC, and inverter. You do not mention battery. Since panels only deliver wattage based on loads it is hard to know if you are getting less than you should expect to get. From all I have personally seen and read you can expect about 75% of rated watts output during full load condition at peak sun hour.

 

[Dallascowboy]

You mention panels, SCC, and inverter. You do not mention battery. Since panels only deliver wattage based on loads it is hard to know if you are getting less than you should expect to get. From all I have personally seen and read you can expect about 75% of rated watts output during full load condition at peak sun hour.

Thank you for responding. I have a 12v 150AH battery. My understanding is the battery is not a concern for peak power output under full sun. At 75% output I should expect 560W, instead the max I get is only 350W.

 

[Bud Martin]

I have a 3 panel PV system with panels rated at 250W and 36V each connected to a MPPT charge controller and 2000W inverter. The solar array is panels connected in parallel. The maximum output I have been able to measure so far is 350W. I have noticed that when it is under a connected load (such as a small portable air conditioner), the voltage drops to like 14V (at about 24 Amps). Not sure what is going on and how I can get as close as possible to 750W at 36V.

I do not expect 100% efficiency by any means, but currently I am at less than 50% efficiency. The data shared here is under full sun exposure. Any help or suggestions to troubleshoot will be much appreciated.

1) What is your system Voltage?
2) "the voltage drops to like 14V (at about 24 Amps)." is that panel Voltage measured at the PV input of the SCC?
3) Make and model of the SCC?
4) "250W and 36V" Is 36V Voc or Vmp? Spec of the panel?

 

[Dallascowboy]

1) What is your system Voltage?
2) "the voltage drops to like 14V (at about 24 Amps)." is that panel Voltage measured at the PV input of the SCC?
3) Make and model of the SCC?
4) "250W and 36V" Is 36V Voc or Vmp? Spec of the panel?

System voltage under no load is around 31V (panels are in parallel). This is measured at the SCC. Brand for SCC is PowMr. I checked incoming PV readings with a clamp meter as well and it matches the SCC reading.

 

[Dallascowboy]

1) What is your system Voltage?
2) "the voltage drops to like 14V (at about 24 Amps)." is that panel Voltage measured at the PV input of the SCC?
3) Make and model of the SCC?
4) "250W and 36V" Is 36V Voc or Vmp? Spec of the panel?

System voltage as measured on the SCC (PowMr brand 60Amp MPPT) is around 31V. I compared the amp readings on a clamp meter and it is consistent. The voltage is Vmp.

 

[Bud Martin]

The system Voltage means what the battery Voltage you are running, I.E. 12V, 24V, 36V, 48V.

 

[Mattb4]

Thank you for responding. I have a 12v 150AH battery. My understanding is the battery is not a concern for peak power output under full sun. At 75% output I should expect 560W, instead the max I get is only 350W.

It is possible that your SCC controller is not making full use of available power. The only reason the battery is a concern is Charge controllers will reduce charge current as the battery approaches full charge.

When I test my panel output I use a space heater as my load. it provides sufficient draw that after a few minutes running I know that the SCC has sensed the battery has reached the state it will take all the SCC can give it.

Other possibilities are line loss, if you have a long run from the panels, wire size being too small, and even poor connections between the panels and SCC.