405 W PERC solar panel with 120 cells. Voc 41.6 V · Isc 12.4 A · TcVoc -0.25%/°C.
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String Compatibility Calculator
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How the Algorithm Works
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Voc
41.6 V
Vmpp
34.64 V
Isc
12.4 A
Impp
11.7 A
TcVoc
-0.25 %/°C
TcPmax
-0.34 %/°C
Pmax
405 W
Cells
120
Length
1754 mm
Width
1096 mm
Thickness
30 mm
Weight
21 kg
The Risen RSM40-8-405M is a 405 W solar panel. Finding a compatible replacement requires matching the original electrical characteristics — particularly Voc, Vmpp, Isc, and temperature coefficients — to ensure safe operation within the same string.
Use the form above to find panels that match these specifications. Then verify the replacement in the String Compatibility Calculator with your inverter.
| Model | Power | Voc | Isc |
|---|---|---|---|
| 390 W | 40.69 V | 12.21 A | |
| 395 W | 41 V | 12.27 A | |
| 400 W | 41.3 V | 12.34 A |
The most critical specs to match are: cell count (must be exactly 120), Voc close to 41.6 V (within ±5%), and temperature coefficient TcVoc close to -0.25%/°C. If Voc differs significantly, the string voltage at extreme temperatures may shift outside the inverter's MPPT range. The replacement finder above pre-screens all candidates by these criteria.
A higher wattage panel usually has a higher Vmpp or Isc, which can affect string voltage and current. Small increases (up to 10–15%) are typically safe if the other electrical specs align. The replacement finder shows a compatibility score — 'Exact match' means the specs align closely. Always verify the replacement in the String Compatibility Calculator with your inverter before installation.
If the replacement has a significantly different Voc or Vmpp, the string voltage may shift outside the inverter's MPPT range, reducing energy production or causing faults. This effect is amplified at temperature extremes: at low temperatures, voltage rises by the TcVoc coefficient. The replacement finder automatically accounts for this — it scores candidates by how closely the electrical specs match the original Risen RSM40-8-405M.