The first step for simulating photovoltaic systems is modeling the irradiation.

The irradiation on the PV modules is calculated from the climate data, which usually contain the ambient temperature and the solar irradiation in hourly resolution. This requires a series of partial steps:

  1. Calculation of the sun position
  2. Calculation of extraterrestrial radiation
  3. Calculation of the geometry of module area and angle of irradiation (tracking)
  4. Division of irradiation into direct and diffuse components (Diffuse radiation model)
  5. Calculation of shadowing losses due to distant objects (horizontal shading)
  6. Calculation of irradiation on the inclined plane
  7. Calculation of [ground reflection] (

The irradiance actually available to the PV module is then calculated. This is done in the “PV module” simulation chain.

The radiation generator for time-step-based simulation in PV*SOL.

Input parameters are shown in green, intermediate variables in gray and the models that take over the actual calculation in yellow. Blue stands for simple operations such as addition, subtraction or trigonometric calculations.

Time resolution

The simulation of the irradiation and the PV modules can take place in different temporal resolutions. The smaller the temporal resolution, the more accurate the simulation results. By default, hourly values are used in PV*SOL®. For systems with consumers, battery storage or electric vehicles, however, it is strongly recommended to simulate in minute resolution. Minute values are also indispensable for PV systems with dimensioning factors of > 115%.

See Synthesis of minute values of radiation

Input Parameters

  • Time (time step $t$ of simulation)
  • Climate data:
    • GHI: Global radiation on the horizontal (global horizontal irradiance, GHI)
  • Location of the plant:
    • Longitude, latitude, time zone
  • Plant orientation
    • $ \alpha_M $: Azimuth
    • $ \gamma_M $: Elevation (Inclination of the system, 0°: horizontal, 90°: vertical)
  • Information on shading
    • Horizon line or
    • percentage of shading
  • Albedo (ground reflection)

See also