NMOT stands for Nominal Module Operating Temperature, and is also referred to as NOCT (Nominal Operating Cell Temperature).
Understanding NMOT
NMOT, or Nominal Module Operating Temperature, is a key specification for solar panels. It indicates the temperature a solar panel's cells will likely reach under specific environmental conditions. This is important for accurately predicting a solar panel's performance in real-world scenarios, as their efficiency decreases as temperature increases.
Key Aspects of NMOT
- Standard Test Conditions (STC) vs. NMOT: STC (Standard Test Conditions) are used to determine a solar panel's power rating under ideal lab conditions, while NMOT represents a more realistic operational environment.
- Environmental Factors: NMOT takes into account factors like solar irradiance (800 W/m²), ambient temperature (20°C), and wind speed (1 m/s).
- Real-World Performance: NMOT provides a more accurate picture of how a solar panel will operate under typical outdoor conditions, rather than the optimal conditions of STC.
- Why it matters: Solar panel efficiency is temperature dependent and decreases as their temperature increases. A higher NMOT will therefore lead to a greater performance loss.
Example
Imagine two solar panels with the same STC power rating. If one has a lower NMOT than the other, it will likely perform better in hotter conditions, because its cells will operate at a lower temperature, retaining more of its original output.
| Feature | STC | NMOT |
|---|---|---|
| Irradiance | 1000 W/m² | 800 W/m² |
| Cell Temperature | 25°C | Varies, typically between 40-50°C |
| Ambient Temperature | N/A (Cell temperature controlled) | 20°C |
| Wind Speed | N/A | 1 m/s |
