Measuring the cleanliness of solar photovoltaic systems with Soltell's Sensorless technology

The impact of soiling, including dust and dirt, can accumulate in a matter of weeks to over 20% in terms of solar PV performance reduction across the Mediterranean region, susceptible to dust from Middle Eastern and North African deserts. A similar effect is also observed in the South-Eastern and Southern US states. Furthermore, in urban and industrial environments an even more dramatic impact is made by fast accumulation of dust and soot.

Manual or automatic cleaning is essential to restore solar photovoltaic PV performance to optimal levels, ensuring maximum energy output and efficiency. The choice of cleaning method and the frequency of maintenance depend on a variety of factors, including the size of the solar system, the electricity generation tariff, and local soiling conditions. Additionally, local soiling factors such as dust, pollen, bird droppings, or industrial pollutants play a critical role in determining the cleaning schedule, as regions with higher pollution or arid climates may necessitate more intensive and frequent cleaning to mitigate performance losses.

However, the timing of PV system cleaning and its effectiveness for rooftop solar facilities has so far mostly been a matter of an educated guess. Soiling measurement hardware is expensive and requires frequent calibration to provide accurate results, which makes the vast majority of rooftop PV facilities to give up on this costly solution. Now, novel solutions are reaching the market to resolve the issue. The cleanness measurement capability of Soltell's Sensorless technology is a unique predictive maintenance tool for rooftop PV in terms of cleaning schedule, as well as optimizing other aspects of maintenance. It is powered with an Industrial IoT approach, allowing an ability to measure Soiling Ratio (SR) of individual solar PV plants, with no need for any add-on hardware sensor installation and calibration.

Fig 1. Cleanness Factor (inverse Soiling Ratio) of solar PV systems with different system cleaning schedules in the Eastern Mediterranean: frequent cleaning (blue, green and purple) vs infrequent cleaning (yellow).

Soiling effect measurement of rooftop solar PV systems - ability to detect the precise soiling impact on PV system performance with no extra hardware, utilizing Soltell's Industrial IoT capability. Above in Figure 1, you can see the comparison of automatically cleaned PV system (cleaned daily), periodically cleaned PV systems (once 2-3 weeks) and rarely cleaned PV system (once a season). There is an obvious trend of linear soling accumulation during the dry season with different soiling rates for each location, requiring a quantitative assessment for cleaning schedule optimization.

Interested to learn more on the Sensorless technology, in order to optimize your PV fleet cleaning schedule? Fill-in the demo request form to or contact us get more details.