Derating 24v Solar Panels?
I'm considering running two 250w/24v poly panels; tracked/pointed during spring/fall, and flat during the summer; thru the Tracer 3215BN 30a mppt controller. I can also get 200w/24v mono panels, local...
Forum Discussion
Regarding Heat derating:
››› Electrical Characteristics at STC (Standard Test Conditions: Irradiance 1000w/m², Module Temperature 25°C, Air Mass 1.5):
• Module Type: LDK250W Poly
• Maximum Power at STC(Pmax): 250Wp
• Maximum Power Voltage(Vmp): 30.30V
• Maximum Power Current(Imp): 8.27A
• Open-circuit Voltage (Voc): 37.7V
• Short-circuit Current (Isc): 8.39A
• Power Tolerance (%): 0-3
• Maximum System Voltage: IEC EN:1000V/ UL: 600V
• Module Efficiency (%): 15.50
• Temperature coefficients of Pmax: -0.45%/?
• Temperature coefficients of Voc: -0.32%/?
• Temperature coefficients of Isc: +0.06%/?
• Operating Temperature(?): -40?~+85?
• Nominal operating cell temperature (NOCT): 45±2?
Is it correct to say the above co-efficients are to be used at above 45C panel temp, not 25C? If so, that may not allow for very much heat DE-ration.
And how hot do panels get in the summer, anyway?
››› Electrical Characteristics at STC (Standard Test Conditions: Irradiance 1000w/m², Module Temperature 25°C, Air Mass 1.5):
• Module Type: LDK250W Poly
• Maximum Power at STC(Pmax): 250Wp
• Maximum Power Voltage(Vmp): 30.30V
• Maximum Power Current(Imp): 8.27A
• Open-circuit Voltage (Voc): 37.7V
• Short-circuit Current (Isc): 8.39A
• Power Tolerance (%): 0-3
• Maximum System Voltage: IEC EN:1000V/ UL: 600V
• Module Efficiency (%): 15.50
• Temperature coefficients of Pmax: -0.45%/?
• Temperature coefficients of Voc: -0.32%/?
• Temperature coefficients of Isc: +0.06%/?
• Operating Temperature(?): -40?~+85?
• Nominal operating cell temperature (NOCT): 45±2?
Is it correct to say the above co-efficients are to be used at above 45C panel temp, not 25C? If so, that may not allow for very much heat DE-ration.
And how hot do panels get in the summer, anyway?
