When installing solar panels you expect the PV system to operate at the maximum efficiency level for many years.
In reality however, after a certain amount of time a drop in efficiency occurs on almost every installation. Bad weather conditions, mechanical failures and electrical issues after all result in the degradation of the efficiency of the PV system.
Therefore it is important to check the status of your installation at regular intervals for the possible loss of efficiency. Only this way you will obtain maximum solar panel efficiency
Efficiency drop of solar panels explained
The drop in solar efficiency can have various causes. It’s really important to pay enough attention to all of these.
- Firstly, mechanical degradation occurs on all solar panels. Over time the glass of solar panels reflects more light and passes through fewer rays of the sun. This causes an efficiency drop of 2 to 3% per year. Mechanical degradation can be countered by cleaning the panels with the right material. However, in order to prevent from scratches, this should only be done occasionally and with the right equipment. Afterwards the solar panels should be equipped with good coating.
On the other hand, problems with electrical degradation occur. This phenomenon can result in efficiency losses up to 17% in a period of only 2 or 3 years. Electrical degradation is most common in PV systems that were installed after 2008, because since then the cable running from the solar panels to the inverter (negative pole) could not be grounded. Because of this, greater tensions with respect to the earth occur, which results in more leakage current to the earth. This loss of efficiency that is caused by leakage currents and the lack of grounding, also called ‘Potential Induced Degradation’, can now be prevented by means of a PIDbox.
- Even hail damage and pests have a negative impact on a PV installation. Hailstones damage the solar cells while pests may gnaw on the wires of the system, both with negative consequences for the installation.
How to monitor solar cell efficiency?
The efficiency of a solar installation can largely be self-monitored, so one stays informed on its yield and its proper functioning. In order to get a good estimate, the performance and the efficiency can be compared with the number of hour of sunshine over the past period.
The sunshine duration can be looked up via the website of the official meteorological authority your country. You can compare the efficiency of your PV system per year with the number of hours of sunshine per year.