How Long Does a Solar Power System Last: Solar Panels, Inverter, the Lot?

If you ever visit Northwest Germany, and happen to walk by the “Energielabor” building of the University of Oldenburg, you will witness an important piece of the history of solar power. On the roof of the building stands a solar power system, which was installed nearly a half century ago (1976), and is still operational.

This alone is proof of the astounding longevity of solar power systems - or should we say, ‘near-immortality’? But still, the lifespan of solar systems is one of the frequently asked questions, and we decided to answer it in as much detail as possible. Let’s dig in.

A solar power system, although designated as a single large entity, is made up of several separate components connected to one another. Each component is made from different materials and is subject to different types of wear and tear over its life. 

Therefore, we are going to look at the lifespan of all the key components of a solar system, finally commenting on the lifespan of the system itself. We’ll start with the lead character of any system - solar panels.

How Long Do Solar Panels Last?

To be honest, nobody really knows at what point solar panels completely die, meaning they stop producing any power at all. This is because most solar panels that were ever built, and not destroyed in calamities, are still functional, although with lowered capacity.

The more important question is - how long do solar panels produce their rated power? The short answer to that is around 30 years. 

For the longer version, the best way to understand panel life is to look at solar panel warranties. There are two types of warranty/guarantee any solar module comes with:

1. Performance guarantee:

   Each panel undergoes “degradation” with time. Its ability to generate power decreases with exposure to heat and other elements. Panel makers ‘guarantee’ that their product will generate a certain amount of power even after 25 or 30 years. Generally, this is 80 or 90% of the rated power.
   
   The degradation rate of each panel is around 0.5-0.8% every year. This means that by year 30, a panel with 0.5% degradation generates 100 - (30*0.5) = 85% of its rated power.
   
   Obviously, this does not mean you will have to discard your panels at this stage. 80-90% output after 30 years is not bad, and you can get enough energy to help you save on bills for another 10+ years.
   
   A chart explaining the warranty information of a Trina solar module

2. Workmanship warranty:

   While it’s true that good quality solar panels can last well over 30 years, there are cheap products from lesser known brands that can barely last 5-10 years. A workmanship warranty therefore becomes essential.
   
   Most manufacturers provide a 5-year workmanship warranty with their panels. There are some companies who have highlighted their product quality with a striking 25-year workmanship warranty.
   
   In general, panels with a 5 or 10-year workmanship warranty are quite well-built. If a panel does not stop working in the first few years, it likely won’t in the next 20 or 30 years.

A chart explaining the warranty information of a Trina solar module

In conclusion, solar panels are simple, static devices with no moving or heating parts, and if they are well-built, they will last impressively long.

How Long Do Solar Inverters Last?

Another essential component of any solar system, inverters make up over 20% of the total cost, and it thus becomes necessary to look at its lifespan. Unlike solar panels, inverters last somewhere between 10-15 years. After that, you will have to replace it with a newer one.

Inverters have a more complex assembly of electronic components than that of solar panels, and are also subject to heating. This is the reason for its relatively lower lifespan. Regardless, the system saves enough over its lifetime to justify the replacement cost of the inverter.

Most name-brand inverters, like Fronius or SMA, come with 10-year warranties, and perform efficiently for a few more years beyond that too.

How Long Do Solar Batteries Last?

Batteries are used with solar panels to store excess energy during the day and use it at night, or on overcast days. Although not absolutely essential, many homeowners choose to go with a battery bank for its obvious advantages.

Traditionally, lead-acid batteries were used in solar power systems. These batteries lasted 5 years at best, and required frequent maintenance. With the advent of lithium ion batteries, this number has gone up to 10. Li-ion batteries do not need any maintenance, and often come with 10-year warranties.

Similar to solar panels, a battery won’t stop working in its eleventh year. It will still charge and discharge, albeit with a lower capacity.

A chart showing battery capacity degradation with use (source - Aginnovators)

The life of a battery depends on several factors, such as storage conditions (ambient temperature), intensity of discharge current (higher the intensity, lower the life), and the average depth of discharge for each cycle (the higher the DoD, the lower the life).

Lifespan Of Solar Racking, Wiring, And Miscellaneous Components

Aside from the above three key components, a solar power system comprises of racking/mounting structures, wiring, combiner boxes, fuses, circuit breakers, etc.

The racking is simply metal structures standing and holding the solar panels together, like miniature versions of electrical towers. They are made from or coated with non-corrosive material, and rain, moisture, or other elements don’t affect them. Naturally, the racking often outlasts a solar system, unless destroyed by a natural calamity, which is not very common.

A typical solar panel mounting structure

The wiring and other electrical and electronic equipment is also built to last multiple decades. Unless a fuse blows up or there is physical damage to one of the components (a mouse chewing on wires, for example), the miscellaneous components and wiring also last long enough to not need a replacement.

Summing It Up

One of the best things about solar power systems is that they are exceptionally predictable. There are hardly any surprises throughout the lifespan of a system. This is true about the system’s longevity too - unless an unexpected external factor affects it (storms, vandalism, etc.), solar power systems keep working for a seriously long time.

Except for the inverter and the battery, which need a replacement maybe once throughout the system’s life, everything else just keeps on going, seemingly for eternity. As for the inverter and the batteries, the system saves enough money over the 3+ decades to easily justify the replacement cost of these items.

In conclusion, there’s hardly anything about solar systems you need to worry about, and their lifespan is certainly not one of those things.