May 27, 2016
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A study by the National Renewable Energy Laboratory found that the median solar panel efficiency loss is 0.5%.
This loss is mainly because of ultraviolet radiation which will slowly break down the silicon components in photovoltaic cells. At a 0.5% efficiency loss per year, your solar panels will still work at 90% of the efficiency 20 years after your solar panels are installed.


Other factors can affect the efficiency loss on solar panels. Dirt, pollen, and mineral build-up on the solar panel housing from rain and storms can block sunlight from reaching the photovoltaic cells. It is important to properly maintain and clean your solar panels to ensure they are working at their full potential.

It is also important to check your solar panels after a large storm. Solar panels are built to withstand damage from hail, however cracks and breaks can lead to higher efficiency losses. Cracks can lead to oxygen contamination and water damage that can rust and damage solar panels soldering and wiring.


Your solar panel manual will include output rates typically measured in volts. These advertised output rates are measured under full sunlight conditions, so you will have to test when there is full sunlight on your panels. You will need a multimeter and access to your solar panel converter for this test.

    • Set your multimeter to measure for DC and in Volts. Depending on the size of your system, you should have your multimeter configured to withstand well over the intended output volts. If your system’s output is 30 volts, you will want to set the range that the multimeter can detect to be over 30 volts.
    • Connect the positive multimeter lead (red) to the positive converter terminal, and the negative lead (black) to the negative terminal.
    • The multimeter’s reading will not be fully accurate, but it will be able to give a whole number output value for your solar panels voltage.
    • Use the voltage amount and compare it to the solar panels advertised output rates


A high percentage of solar panel efficiency loss is usually due to a defect or failure. Cracks, faulty soldering, improper wiring, inverter issues, or installing problems can all cause efficiency loss.

Because defects and issues can happen, it is common that solar panels come with a 15-30 year warranty. It’s important to do proper research on the solar panel manufacturer before choosing a product. Some solar companies that have manufactured faulty systems can go out of business and fail to fulfill warranty requests.

At CAM Solar, we will advise you on choosing the right solar panel manufacturer so you can get the best warranty from your investment.


If your solar panels are not working correctly, or are interested in investing in a solar panel system Cam Solar can help. Contact us today to learn more.



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