Direct Radiation

In photovoltaics, direct radiation refers to the portion of solar radiation that reaches the Earth's surface directly from the sun, without deviation. In contrast to diffuse radiation, which results from scattering by clouds, dust, or air molecules, direct radiation retains its original direction.

Importance for Photovoltaics:

  • Higher Efficiency: Direct radiation is generally converted more efficiently into electrical energy by solar panels compared to diffuse radiation. This is because solar cells are optimized for direct sunlight.
  • Yield Impact: The amount of direct radiation at a specific location significantly affects the yield of a photovoltaic system. The higher the proportion of direct radiation in the global radiation, the higher the power output tends to be.
  • Site Selection: When planning a photovoltaic system, knowledge of the average direct solar radiation at the location is a crucial factor. Regions with high direct solar radiation, such as southern countries or sunny high-altitude areas, are especially suitable for the installation of solar systems.

Influencing Factors:

  • Time of Day: Direct radiation is highest when the sun is directly overhead, typically around noon.
  • Season: Direct radiation is more intense during the summer months compared to winter months.
  • Weather: Cloud cover significantly reduces direct radiation, as a portion of the sunlight is scattered.
  • Geographic Location: The geographic latitude and altitude above sea level influence the intensity of direct radiation.

Measurement:

Direct radiation is measured using pyranometers, which are specifically designed for measuring direct solar radiation.

Interaction with Diffuse Radiation:

Although direct radiation is desirable for high yields from a photovoltaic system, solar panels can also utilize diffuse radiation. Modern solar panels are designed to convert both direct and diffuse radiation into electrical energy as efficiently as possible.

Conclusion:

Direct radiation is a crucial factor for the performance of photovoltaic systems. Understanding the properties and influences of direct radiation allows for optimal planning and operation of solar systems.

Additional Keywords: Global radiation, Solar panel, Solar radiation, Photovoltaic yield