If you ask somebody “How long do solar panels last?”, the general answer is “25 years or longer”. While it is a good number to work with, there is more to the subject of solar panels lifetime. In this short article we are going to discuss how panels behave during their lifespan, how to take care of your installation and make it last for decades.
All solar modules gradually lose their power as time passes. The first year is the roughest because the panel gets exposed to solar radiation for the first time: a panel can lose 2-5% of its rated power output in these 12 months. Then power losses or so-called degradation rate decrease to 0.7%-0.8% on average. After 25 years in service a panel generally retains about 80% of its initial output. There are brands that manage to keep the degradation rate of their panels very low, like Panasonic or REC. Their panels lose only 0.3%-0.4% annually and in the end retain over 90% of their rated production. The degradation rate gets higher for installations in arid and hot climates – deserts, for example. Besides losing power, panels tend to lose their color over time and old panels are easy to distinguish from new ones.
Solar panels rarely fail, especially when they are of a brand with a good reputation and supplied by a reliable company. For example, Panasonic solar panels failure rate is around 1 malfunctioning module in 22,700. Malfunctioning usually shows itself in the fact the panel doesn’t produce energy or produces very little. But if you heard stories of panels exploding under the sun, don’t believe them – they are simply not true. If you haven’t damaged your purchase yourself, it’s often possible to return the panel and get a new one, making use of product warranty.
Good maintenance is what prolongs the lifetime of solar panels and the installation in general. If you take proper care of the modules, they can last for up to 50 years. Of course, it is the best case scenario with the most high-quality modules and obviously they are not going to give you nearly as much power after a couple of decades.
To make your PV modules last longer we recommend to perform a visual inspection from time to time. Most importantly, check connections! Cleaning modules every now and then improves the performance of panels, especially if it’s a ground-mounted installation. A certified electrician can identify possible issues, like hot spots developments or microcracks, and give recommendations on possible actions.
Inverter is much more fragile than PV modules and is more likely to break down than any other part in your solar system. It’s because the inverter has more functions than anything else in the installation. Not only does it convert DC from panels to AC, it interacts with the grid, maximizes the production of an array, keeps count of energy consumption and acts as another safety barrier. Usually, inverters last for 15 years or so, though you can find reliable high-quality models with 25 year product warranty. We recommend:
Batteries can be extremely fragile and the lifetime of your energy storage highly depends on how you treat it. A traditional lead-acid battery can serve you for up to 10-12 years. However, if you overcharge it constantly or use it when it’s not charged, it dies in a couple of months. The same story goes for gel batteries, though their lifetime is a bit longer. Modern lithium-ion batteries are less maintenance-depended and less vulnerable to deep discharge and overcharge. This type of energy storage can last for 20-25 years.
Whenever you use batteries with your photovoltaics, add a solar controller to your system. The charge controller keeps your battery bank safe from deep discharge and overcharge, plus lets you monitor the state of your battery. Buying it is cheaper than purchasing a new battery every few years. A controller by itself can last for 15-20 years.
There are three most popular types of photovoltaics on the market. These are monocrystalline, polycrystalline and thin-film panels. The average lifetime of solar panels of the first two types is similar: over 25 years. Thin-film panels tend to break down sooner, after 10-15 years in exploitation. However, their construction improves with every year and their lifetime gradually gets closer to two other types. Bifacial monocrystalline modules also gain popularity and we could put them as a subtype of monopanels. While the lifetime of mono- and bi-facial modules are similar, bifacial modules often have better degradation rates.