Does rain affect the energy production of crystalline photovoltaic modules?

In this sense, numerous studies have been performed in the past decades to assess the influence on the energy production of crystalline photovoltaic modules of several factors, such as spectral quality of solar irradiance, temperature, wind speed, soiling, snow etc. but so far the effect of rain appears scarcely investigated.

Does rain prevent performance losses on tilted PV modules?

To confirm such results, a specific test carried out on tilted PV modules in urban environment without particular sources of dust (Milan) found that rain operates an effective cleaning of big particles of dust thus preventing significant performance losses.

How does rain interact with the surface of PV modules?

Rain interaction with the surface of PV modules From a physical viewpoint, a water drop deposited on an ideal flat homogeneous surface is a system composed by three boundaries (solid/water, solid/air and water/air), where the water/air interface forms a static contact angle 1 θ (see Fig. 3) with the water/solid interface .

Does rain affect surface cleaning tilted PV modules?

In conclusion, it can be confirmed that rain has a positive impact on the surface cleaning tilted PV modules (i.e., up to 6%), especially in dusty environment and if rainfalls are convective type, thus quite intense.

How much rainfall is needed to clean titled PV modules?

In a specific study on the topic, authors concluded that at least a 20 mm rainfall is needed to clean the surface of titled PV modules in dusty environments, otherwise the system will continue to experience power loss due to the dust and soil disposition.

What happens if rain stops a solar module?

When the rain stops, if we assume to have roughly 1 mm maximum of rain layer accumulated on the glass (see considerations above about the water accumulation), the residual cooling effect, which is mainly evaporative, helps to slow down the raise of the module temperature due to the solar irradiance.