Nominal Power
Nominal Power is a central term in photovoltaics, indicating the maximum electrical power that a solar module or an entire photovoltaic system can deliver under standard test conditions (STC). These conditions include an irradiance of 1,000 W/m², a cell temperature of 25 °C, and a spectral distribution of light that corresponds to the solar spectrum at noon.
Importance of Nominal Power:
- Power Specification: The nominal power is the most important metric for the performance of a solar module or system. It indicates how much electrical energy can be generated under optimal conditions.
- Dimensioning: The nominal power serves as the basis for sizing photovoltaic systems. The number of modules required to meet the desired energy demand is calculated based on the nominal power.
- Comparability: The nominal power allows for an easy comparison of different solar modules and systems. Modules with higher nominal power typically generate more electricity.
Influencing Factors on Actual Performance:
Although the nominal power provides important guidance, the actual power generated depends on various factors:
- Irradiance: Solar irradiance varies depending on location, season, and time of day. Cloud cover or shading reduces performance.
- Temperature: The performance of solar cells decreases at higher temperatures.
- Module Aging: Over time, the performance of solar modules declines due to soiling or material aging.
- Angle of the Modules: The orientation of the modules towards the sun affects the incoming radiation and thus the performance.
Important Note:
The nominal power does not indicate the average performance of a system but rather the maximum possible performance under ideal conditions. The actual annual yields are typically significantly below the nominal power.
Relevant Keywords: solar module, solar system, power, STC (Standard Test Conditions), irradiance