40 W TOPCon solar panel with 36 cells. Voc 25.45 V · Isc 1.99 A · TcVoc -0.26%/°C.
Select the panel you want to replace
1 panels found · 3510 panels excluded
45 W
TOPCon| Parameter | Original | Replacement | Deviation |
|---|---|---|---|
| Voc | 25.45 V | 25.45 V | 0.0% |
| Vmpp | 21.81 V | 21.81 V | 0.0% |
| Isc | 1.99 A | 2.24 A | 12.6% |
| Impp | 1.84 A | 2.07 A | 12.5% |
| TcVoc | -0.26 %/°C | -0.26 %/°C | ±0.000 %/°C |
| TcPmax | -0.3 %/°C | -0.3 %/°C | ±0.000 %/°C |
String Compatibility Calculator
Verify the replacement panel works with your inverter
Panel Matcher
Find all compatible panels for a specific inverter
Already have panels?
Find an inverter that fits your panel array with the right MPPT range and DC/AC ratio.
How the Algorithm Works
Learn how panels are scored and matched
Voc
25.45 V
Vmpp
21.81 V
Isc
1.99 A
Impp
1.84 A
TcVoc
-0.26 %/°C
TcPmax
-0.3 %/°C
Pmax
40 W
Cells
36
Length
680 mm
Width
430 mm
Thickness
20 mm
Weight
3.32 kg
The TommaTech TT040-36TN10 is a 40 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 |
|---|---|---|---|
| 45 W | 25.45 V | 2.24 A |
The most critical specs to match are: cell count (must be exactly 36), Voc close to 25.45 V (within ±5%), and temperature coefficient TcVoc close to -0.26%/°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 TommaTech TT040-36TN10.