- PV module: 550W, Voc = 49.5V, Vmp = 41.2V
- Inverter input voltage range: 200V – 1000V:

- - PV module: 550W, Voc = 49.5V, Vmp = 41.2V
- Inverter input voltage range: 200V – 1000V
- Temperature at site:
- Min temp (coldest): -5°C
- Max temp (hottest): 45°C
- Temperature coefficient of Voc: -0.28%/°C

 Step-by-step:

1️⃣ Correct Voc for minimum temp:

Voc corrected=Voc+[Temp Coeff×(STC temp−min temp)×Voc]
STC = 25°C
Voc corrected = 49.5 + [−0.0028×(25−(−5))×49.5] = 49.5+(0.0028×30×49.5) = 49.5+4.158 ≈ 53.66V

2️⃣ Max number of modules in string:
Max inverter input voltage Corrected Voc=1000V / 53.66V ≈ 18 modules max per string

3️⃣ Vmp at 45°C (for lower voltage limit):
Temperature coefficient = -0.28%/°C
ΔT=45−25=20°CVmp corrected = 41.2−(0.0028×20×41.2) ≈ 41.2−2.31 ≈ 38.9V

Min total Vmp} = 38.9V × 18 ≈ 700V > 200V (OK)

✅ Conclusion: You can use 18 modules per