Panel Efficiency Loss and Recovery
The portion of the fall in photovoltaic output caused by soiling that can be recovered by cleaning. The loss varies with site conditions and accumulates over time; the efficiency gain declared for AXI's ROBEG ELS-03 solar panel cleaning robot is in the range %15 to %30.
Not all of the fall in panel output is recoverable. Part of the loss is permanent: the annual ageing of the cells, yellowing of the encapsulation material and micro cracks do not come back with cleaning. The recoverable portion is the loss caused by the layer of soiling on the surface.
The way to make this distinction is to measure. Output values taken before and after cleaning under similar irradiance and temperature conditions are compared. The difference between them gives the true share of the soiling. A single measurement is not enough; differences in irradiance and temperature can make the result misleading.
The %15–30 range declared for the ROBEG ELS-03 points to the gain obtained by cleaning at sites with a high soiling load. This is not a fixed figure guaranteed at every site but a range depending on the degree of soiling: on a string kept clean the gain naturally stays below the lower bound. The robot works with an 800 mm industrial brush without damaging the panel surface and repeats the operation with minimum water consumption.
The context in which this term is used: Solar plant panel soiling and robotic cleaning