That’s the reason why understanding what determines the longevity of solar panels is crucial. When browsing the web and manuals, you will rapidly find out that the expected lifetime people agree on is at least around 25/30 years. A number of elements give consistence to this expectation. First of all, most of the solar panels manufacturers offer a 25 years performance guarantee, when it is not a 25 years product guarantee as well. When most of the supporting schemes were relying on Feed-In Tariffs, the contracts were established for a 20 years period. Last but not least, some old installations are still performing reasonably well after 30 years.
Thus, in theory, one can expect solar panels to work properly for two to three decades. BUT, it should never ever be considered as a given. If someone believes that going solar is only about throwing whatever solar panels on a roof and that reliable solar electricity supply will be ensured for two decades without efforts, then he may be exposed at best to a significant disillusion and worst to financial troubles.
So if you want your solar panels to have the longest lifespan, you should better know and take into consideration the 6 following elements.
1. Quality of components
This is of course the core of a long term approach. Like any industrial good, the lifespan of solar panels is deeply related to the quality of their components. Would you imagine using your car for several thousand of kilometers and being protected against accidents without a minimum of quality. This is exactly the same in the solar industry. Most of the solar panels are built with the following components, all being exposed to potential failures:
– Glass – it can break under mechanical load, front side coating can degrade over time, …
– Aluminium frame – ill-designed frame can allow freezing during winter, breakage under heavy load like snow…
– Solar cells – they can be subject to microcracks, hot spot…
– Encapsulant – it can become yellow because of UV…
– Tedlar – it can delaminate…
The best manufacturers developed over time stringent selection methods that go beyond what is usually required by international certification like IEC 61215. They usually use methods to simulate stress during the expected lifetime of the solar panel combining the influence of temperature variation, humidity, mechanical stress, UV… So all components are not born equal and the first challenge to ensure a long lifespan is to select the right Bill of Materials. With the huge number of potential suppliers, it is not enough to rely only on the supplier’s certification and then find a good price. Without established in-house testing and selection processes, the risks are significantly increased.
2. Quality of assemblage
Together with the components selection, the quality and know-how in assemblage is of utmost importance. Indeed, you have to know that all materials do not necessarily work well together. Which means that this is not just about selecting the best components. You need to select the best components working well together. This is an other story. Ultimately the combination of the two will determine how long your solar panels will last.
The conquest of quality in our industry is a long story. The truth is that it is still an ongoing story. The solar industry is still a young and burgeoning domain. We have not yet reached a level where high quality standards are spread evenly so that you could choose your supplier with your eyes shut. For several years now, PV manufacturers are growing aggressively while at the same time seeking to rapidly reduce costs to preserve margins considering the huge competition between players. Naturally, in this kind of environment, not all products are the same because inevitably, along the value chain and its different actors, some will make trade-offs at the expense of quality and solar panels lifespan.
3. Quality of installation
If you buy the best solar panels but you get them poorly installed, then you put at stake your asset expected lifetime. As far as solar panels are concerned, there are several elements to consider :
– Store and transport modules so as to avoid microcracks
– Check any visible defect before installation
– Make sure handling provokes no damage: scratch on the backsheet for example
– Ensure proper electrical connections
– Respect slope and clamping to ensure optimum self cleaning and mechanical resistance
– Avoid shadowing not to put useless stress on protective diodes in the module
– Perform cabling with safety in mind
4. The degradation rate
Once your modules are properly installed, their performance will degrade over time. This is normal and known. This is mainly caused by thermal stress and mechanical influences that will impact the components of the solar panels. On modern technologies, the degradation rate should be less than 1% per year. Most of the manufacturers display this value within their guarantees. Of course, when everything runs well, it can be that the level of degradation stays really low.
5. External conditions
Among the things that are not under control are the climate conditions under which the solar modules will operate. Whether the modules are installed in an extremely hot region or in humid climates, their behavior will be impacted.
An old myth is that solar panels do not need maintenance. This is definitely not the right mindset. When you think about the fact that you will own an asset for electricity production and that you rely on it for the next twenty years, taking care of it should actually be one of your top priorities.
The first thing to do is to combine your solar panels with a monitoring system. Without data, it is much more difficult to know if your installation is working properly and identify issues when there are.
Then, we recommend to always keep an eye on your solar panels to see if there are shadowing (stuck leave…) or dust and to schedule regular maintenance to check junction box, visible connections and cable and check grounding in particular.