Solar system maintenance and cleaning.
Does the dirt visibly collect on the frame edges of your solar modules or do your modules no longer “shine”? Do you have yield losses or no increasing yields in recent years? Then solar system maintenance and cleaning of your photovoltaic system is probably due.
Here below one can see the difference between a solar panel that has been cleaned, and one that has not yet been cleaned:
Solar system energy production and monitoring
It is normal for solar system to lose energy production as they age at a rate of about 1% per year. But if the energy production of your solar system is significant lower than expected, it might be time to clean the panels. It is therefore also necessary to regularly monitor the energy production of your solar system. All good solar systems comes with a user-friendly online monitoring portal for your system.
Here is an example of an energy monitoring system showing monthly energy production, compared by year. In this example the total monthly energy production is compared side by side for each year. There was various factors affecting this system.
Why solar panel cleaning is required
Over time, you will find that your photovoltaic modules are covered with a fine film of environmental dirt. The amount of dirt depends on the roof pitch and the type of modules used. Although most dirt is cleaned automatically by rain, this fine film is not removed. This makes it necessary to manually clean the panels, as this film of dirt can cause a yield loss of up to 15% per year. Another problem arises at the frame edges, where the dirt collects. Normal tap water, and a broom can be used for the cleaning of your solar modules. To see what the energy yield of your solar system should be, you can use this calculator.
What factors affect solar panel soiling?
Panels get especially dirty in winter months where there is not a lot of rain to clean the panels, and there is more dust in the air than in the summer. Solar panels installed at a low incline, of say ten degrees or less, also get much dirtier than panels installed at a larger incline.
Loss of revenue
Currently in January 2021, in South Africa, Pretoria, electricity costs R 2.80 per kilowatt hour! At the current exchange rate that is 16 Euro cents, or 19 USD cents. Say your 10 kWp (kilo Watt peak) solar system can produce 1 200 kWh (kilo watt hours) of energy per month in the summer. That is the average amount of energy produced by a 10 kWp system in Pretoria. Then a 15% reduction of energy would be: 180 kWh. Multiply that by the cost of electricity, that means each month you would be losing out on a saving of: R 504.00! (34 USD / 28 Euro) So definitely worth it to spend money and or time to get the panels cleaned.
Residential solar system cleaning
Most residential solar system are easily reachable and easily cleaned by the home owner. However, one might need to get a specialist in to clean panels that are difficult to reach. One needs to determine if it is worth the cost based on the size of system, electricity tariffs, and potential loss of revenue. As a guideline, if you compare the production per month of the last month to the production of previous years, and there is more than 20% difference, then it is probably time to clean your panels.
Commercial solar system cleaning
For large commercial solar systems, soiling can have a big impact on revenue loss. For these systems it is most definitely worth getting a professional cleaning company in to clean the panels.