Just as any other electrical appliance, photovoltaic solar panels will inevitably decrease in performance, efficiency, and solar electrical output over time. Your solar panels will be exposed to the elements, carry an electrical charge, and will age accordingly. The solar radiation which produces solar electricity carries heat with it that will cause the components of your photovoltaic solar panel to become altered and less able to capture sunlight effectively. Less commonly, delamination can occur over time where the plastic layers that shield the photovoltaic cells from the elements will lose attachment.

Solar panel manufacturers provide a 25 year warranty that your solar products will be producing solar power at 80% efficiency from there initial tested solar electrical output rating. This is based on the notion that modern crystalline photovoltaic solar panels will lose function at a rate of about 0.7% per year. This is a major reason why thin film solar panel technology is not ready for mass production. Solar powered thin film silicon technologies degrade at a rate of 5% during their first few months in exposed sunlight. After this initial degradation they level off to a rate of 1% a year.

As a solar products consumer it is economically in your best interest to prevent unnecessary damages and degradation of your photovoltaic solar panels to expedite the return on your invested cost of solar panels. If you are using DIY solar panels you should take great care during solar installation to handle the solar panels delicately and do not damage the frame, wiring, or back sheet of your solar panels. If you are planning on solar installation with trained professionals, make sure you are using a well trusted organization with a positive reputation and reviews.

The biggest threat to the viability of your solar panels is heat. Provide a space for your photovoltaic solar panels that will receive good airflow and do not use concentrating optical systems to focus sunlight on them. Solar power in itself generates heat and by providing a well ventilated area for them to operate will decrease the threat of degrading plastic components and electrical connections. Eliminate dust and other particulate that may have accumulated on your solar panels throughout usage. Wash your solar panels with clean, soapy water occasionally; preferably on a hot day to also cool them down. Never use strong bases on your photovoltaic solar panels as it can potentiate degradation and will cause a decrease in solar power output.

When planning a home solar system it is pertinent to take into account solar panel degradation and design your solar system accordingly. Solar panels for sale from large well reviewed manufacturers will degrade at a rate of approximately 0.5% a year to 0.7% a year. Track and record any decreases in solar power output and calculate whether this loss of solar electricity is considered normal or abnormal. In a solar power systems designed with photovoltaic solar panels from lesser known manufacturers, assume that the solar panels will degrade in solar electric output by 1% per year.  

Understanding that your solar panels will degrade will allow you to make better decisions when purchasing solar products that will outlive the solar panels themselves. In a grid tied system, understanding solar panel degradation should lead you to purchase an inverter that can accommodate input voltage from a middle to upper end of solar power range for a given solar power system. If your solar power system is designed to hold 12 panels, it would make sense to purchase an inverter that can handle anywhere between 10-12 panels worth of power.  

Solar panels for home use will degrade eventually and lose efficiency; however by purchasing high quality photovoltaic solar panels and taking care of them with minimal maintenance, you can be assured that if nothing else, the warranty will cover any loss in solar power efficiency over the next 25 years.