A good gradient for for Solar Panel require very little cleaning service throughout it life time. However, some types of installation really require a frequent cleaning to ensure the cells are not covered by “thick mud” of which it prevent sufficient sunlight from reaching the cell or Photo Voltic. Poor penetration of sunlight means poor generating of electricity.
In this particular case, look likes the gradient for the whole panels is only 2-3 degree.
In the case as images below, there are 384 pieces of 260W Solar panel on two roof tops that badly need some cleaning. A layman may think that as the panels are all on the roof top, they should be clean and do not require any cleaning, but the fact is, all those dirt and mud are the result of dirt particles in the higher environment and fallen on to the panel with the rain water or by the wind.
Upon look at all those panels, they were super dirty….considered as having thick mud on its surface. About 60 – 70% of the total panels were covered by thick and solid dirt. However, after those panels being cleaned, we do not know whether there was improvement in power generation or no improvement as the corporation seem not knowing so much on monitoring the performance.
Besides the dirt as in those images above, below here is another issue. These yellowish dirt was the result of some chemicals produced by the large few set of air-conditioner unit exhausts. The “fumes” from the air-con exhausts blow directly near to these panels and made a very solid traces stick to the panels as below. You can’t scratches them to remove them or else the panel will get scratches or the cells will get broken, or even the tempered glasses will be broken. Even we failed to scratch them off from the aluminium frame itself with metal piece !. They have become very solid as solid as something that you have cemented !. So, to avoid much trouble, we just left those affected panels as they were but just wash off the dirt.
We use a soft broom / very soft broom and applied very light dish washer solution to clean the stubborn thick mud / dirt. The dirt won’t be removed if we were just using water. Its a very tedious task as every cell need to be clean and on top of that, there were very little spaces to walk through or even no space to pass through.
Below here are some of the cleaned panels. You can’t see them properly as the photos were taken during the night with only one spot light. The job was carried out at night to avoid any shut down to the system.