Purchasing solar panels is often compared to purchasing a car. Some choose to pay for them upfront, while others rather finance them; both are expected to generate a ROI; and you need electricity for a dependable way to power your home, just like you need a vehicle for a dependable way for transportation; However, there are many ways in which the two purchases differ, one of them being expected lifespan.
The average solar panel lifespan for solar panels we recommend is around 25 to 30 years. Most clients make a return on their solar investment by the ninth year, making solar a no-brainer when done by a professional team with high quality materials.
Structurally, solar panels are resilient to harsh elements. We could write all about how strong they are, but it would be better for you to witness it in this great video created by Mission Solar – a San Antonio based solar panel manufacturing company:
Solar panels are clearly strong, but a system installed with poor quality equipment can fall apart quickly. Any exposed wiring, loose racks, or material degradation cause a decline in a panel’s lifespan, but that doesn’t mean you should fix it yourself. Tampering with the equipment could void your warranties. See below for a few examples of solar done wrong that we’ve seen:
exposed wire mixed with flammable leaves; fire hazard
improper setup; poor quality sealant
A savvy homeowner should also be concerned about the degradation of the system when considering solar panel lifespan. You see, just because solar panels are strong enough to last a lifetime, doesn’t mean the panels will maintain the same production for a lifetime. This is where degradation comes into play.
A study done by the National Renewable Energy Laboratory (NREL) wanted to determine the rate of degradation for solar panels. They used data collected worldwide over a 40 year span. The study found the average degradation rate for solar panels installed post-2000’s was 0.7%/yr and the median value was 0.5%/yr. Based on this study, your solar panels should be at 90% power output after 20 years. However, most of the equipment warranties are for 80% output for 25 years. One manufacturer that stands out is Jinko Solar. In addition to the 25-year warranty, they also provide a 12-year warranty for 90% output.
Some factors to consider about the study:
Now that we know the average degradation rate, let’s explore what can increase or decrease the rate. Here are the key factors: temperature, shading, and mounting position.
Many have the misconception that solar panels are more efficient in the heat. While it is true that UV rays from sunlight will cause the panels to generate electricity, extreme heat conditions can cause solar panels to degrade faster. The optimum temperature range for solar panels is 50 to 140 degrees F. However, they can still generate electricity from -40 degrees F to 185 degrees F.
Solar panels placed a few inches off the surface of the roof reduces the amount of heat. Having that gap available for air to circulate not only helps cool down the panels, it also helps keep your roof cool.
The typical culprits that cause shading are:
Solar panels do still work in shaded areas, but they will cause significant degradation. We always recommend to homeowners with overarching trees to have them trimmed before having their solar panels operating. This isn’t just good for your energy production, it also eliminates a safety hazard. Falling tree incidents can destroy your roof and damage your home’s infrastructure.
Tree blocking panels; significant degradation in production
Another factor to consider is cloud coverage. If your property is located in Cold Bay, Alaska where you only get 60 days of sunlight, then yeah… maybe a wind turbine would be better.
Most cities in Texas receive over 220 days of sunshine. We use a state-of-the-art software called Aurora that allows us to generate customized shading analysis and energy production estimates based on satellite imagery of your home. A Solar Edge Pros consultant will take into account your energy usage for the entire year as well as your energy goals during your solar evaluation. Learn more about the solar process here.
The satellites used can also determine how high your roof is relative to the ground and other parts of the roof. This is helpful information when designing a system layout to produce the most amount of electricity and you want to avoid shaded areas, particularly areas where a rooftop casts shadows onto itself:
Roofs aren’t the only thing that can cast a shadow on itself, sometimes your solar panels can too. When designing a system layout, we make sure the panels are spaced the right distance to avoid shading each other, an issue more common with panels on a north-facing roof. Which is a great segue for the next factor in solar panel degradation.
The single most important factor to consider when going solar is where the panels are placed. Your solar panels will not be producing as well as they could if they’re facing the least efficient direction. Solar panels can also produce more energy when appropriately angled on your roof. Most roofs do not have the same pitch. Installers need to make sure the panels are mounted at the appropriate angle from your roof to the sky, which is around 30 degrees for year-round production, to capture the most of the sunlight.
Renewable energy can make a great investment when done properly. Although complicated at times, going solar saves you a lot of money considering a panel’s long lifespan. When you hire a solar professional, you get all of the benefits without undergoing the necessary training and certificates. If you would like to learn more about how solar works, attend our solar installation workshop every Friday, or simply give us a call at (210) 401-9030 to schedule a solar evaluation for your property.
David is an Air Force veteran with a Masters in Diplomacy from Norwich University. He is currently Solar Edge Pros' Director of Marketing.