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The true cost of solar module soiling

Increasingly, the solar energy industry is reporting an unsatisfactory incidence of losses, both financial and productive, that relate to the detrimental effects of solar module soiling. Here at PES we decided to take a closer look to find out what solar module soiling is, what the effects of it are, and what can be done to prevent or reduce it. We uncovered how Kipp & Zonen are forging ahead with their innovative and cost-effective solution.

What is solar module soiling?

Solar module soiling is caused by airborne pollutants and particles such as sand, soil, salt, bird droppings, pollen, snow, frost, and differing variants of dust particles such as silica, ash, calcium, and limestone settling on the PV module surface. Particles as small as 25 µm that lay on the ground become ‘transported’ by wind, agricultural practices, volcanic activity, transportation, and people and animal movement in the vicinity.

The Middle East and North Africa, (the MENA region) has the most prevalent dust accumulation incidence, but this issue affects PV parks globally leading to increased costs of maintenance, repair, and potential reduction of energy production.

Left unchecked, initially PV soiling can cause between 20-25% reduction in the amount of energy produced, long term accumulation of soiling, especially if combined with humidity, can lead to cementation of particles ultimately causing complete loss of yield as a hard opaque layer is formed that is almost impossible to remove. The severity in accumulation of airborne pollution and contaminates is exacerbated in more arid environments (precipitation usually needs to exceed 20ml to impact on cleaning the module surface) and in PV module configurations that have shallow tilt angles.

Most power is generated within a PV site at solar noon when the sun is at its highest point in the sky; sunrise and sunset see the largest loss of production, these times only represent a small proportion of the total energy produced throughout the remainder of the day, however, having accurate monitoring of the level of particle contamination can inform the scheduling of maintenance to reduce operation and maintenance costs (O&M) and realise the full potential of the most productive times for solar energy conversion.