640 W TOPCon solar panel with 66 cells. Voc 48.3 V · Isc 17.19 A · TcVoc -0.24%/°C.
Select the panel you want to replace
Voc
48.3 V
Vmpp
40.1 V
Isc
17.19 A
Impp
15.96 A
TcVoc
-0.24 %/°C
TcPmax
-0.3 %/°C
Pmax
640 W
Cells
66
Bifaciality
85%
The TCL Zhonghuan HSM-ND66-GR640 is a 640 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 |
|---|---|---|---|
| 610 W | 48.5 V | 15.95 A | |
| 615 W | 48.72 V | 16 A | |
| 620 W | 48.94 V | 16.05 A | |
| 625 W | 49.16 V | 16.1 A | |
| 630 W | 49.38 V | 16.15 A | |
| 635 W | 48.2 V | 17.13 A | |
| 645 W | 48.4 V | 17.25 A | |
| 650 W | 48.5 V | 17.31 A |
The most critical specs to match are: cell count (must be exactly 66), Voc close to 48.3 V (within ±5%), and temperature coefficient TcVoc close to -0.24%/°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 TCL Zhonghuan HSM-ND66-GR640.