Models

Sky diffuse irradiance

There are two sky diffuse irradiance models that you can choose from:

• Perez (default)
• Hay-Davies

While the Hay-Davies model takes into account two components (isotropic and circumsolar), the Perez model divides the sky into sectors to adjust the values of diffuse irradiance based on experimental data and taking into account the horizon band effect.

The Perez model is more commonly used and is considered to be generally more accurate. It is also important to note that it tends to calculate slightly more irradiance than the Hay-Davies model (en torno al 1 ó 2 %).

If you want to know more, you can check how to calculate the sky diffuse irradiance in photovoltaics.