What you should know

Solar modules: Output, rated power & efficiency

Solar modules: Output & rated power - current values

The average output and nominal output of solar modules can vary depending on the model, manufacturer and technology. Current ground-mounted solar modules generally have a rated output of around 500 watts peak (Wp) to 750 Wp or more per module. On average, solar modules in sunny regions can generate between 1,000 and 1,100 kilowatt hours (kWh) per year per installed kilowatt peak (kWp). 

Solar modules - average output

The average output of a solar module refers to the actual energy production over a certain period of time. In other words, it is the amount of energy that a solar module produces over the course of a day, month or year. This output can vary and is significantly influenced by factors such as solar radiation, shading, orientation and the inclination of the modules. The average output is important in order to have realistic expectations of the energy production of a solar system and to assess its cost-effectiveness.

Solar modules - nominal power

The nominal output of a solar module is measured in watt peak (Wp) and represents the maximum output that a module can generate under standardised test conditions (normally 1000 watts per square metre of solar radiation and 25 degrees Celsius cell temperature). It serves as a reference value for comparing different solar modules. The rated output is an important key figure when purchasing solar modules, as it provides information on how much energy a module can generate under ideal conditions.

Efficiency of solar modules

The efficiency of a solar module is a measure of how efficiently it converts sunlight into electrical energy. It is expressed as a percentage and is typically between 15 % and 20 %. A higher efficiency means that a module can generate more energy from the sunlight it captures. Efficiency is a decisive factor for the performance of a solar system, as modules with a higher efficiency can generate more energy per unit area. Efficiency optimisation is an important goal in solar technology in order to maximise the energy yield and reduce the cost per kilowatt hour generated.

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Solar modules: Factors influencing the actual output

In addition to defects, the following factors, among others, influence the actual output of a solar module:

  • Sunlight intensity: The output of a solar module is directly dependent on the intensity of the incident sunlight. On sunny days with high irradiation, a module generates more energy than on cloudy days.
  • Alignment and inclination: The orientation and inclination of the solar modules play a decisive role. Modules should be aligned in the direction of the sun to maximise solar radiation. The tilt angle should be set according to the latitude of the location in order to optimise solar radiation throughout the year.
  • Shading: Shadows on solar modules lead to power losses. Even slight shading of parts of a module can significantly affect the overall performance. It is therefore important that the modules are positioned away from sources of shade such as buildings, trees or other obstacles.
  • Temperature: Temperature influences the performance of solar modules. High temperatures can reduce efficiency, while low temperatures can slightly improve performance. However, modern solar modules are often equipped with temperature coefficients that compensate for these effects.
  • Quality of the solar modules: The quality of the materials used and the manufacturing processes play a major role. High-quality modules often have better efficiencies and a longer service life.
  • Cleaning and maintenance: Dirty or dusty modules generate less energy. Regular cleaning and maintenance are therefore important to maintain performance.
  • Ageing and degradation: Solar modules are subject to a certain amount of degradation over time, which can lead to a gradual drop in performance. This process is normal, but should be monitored.
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