ASK THE EXPERTS: Inverter Longevity

Intermediate

Another solar instructor and I have a question about grid-tied inverter lifespan. I have read that an average lifespan is 11 to 14 years, and the warranties seem to reinforce this. My colleague believes that 20 to 25 years is more likely for modern inverters. I would tend to believe the latter due to more solid-state electronics in today’s ungrounded inverters, but I can find no data to support this.

Jeff Foster • St. Louis, Missouri

While the expected lifetime of a grid-tied inverter will vary depending on its design, component quality, and the environment it is operating in, lifetimes beyond 14 years are likely for most of the high-quality inverters now available.

For power electronics devices, the environment in which they are installed has a significant impact on their life. I’ve seen inverters fail in less than a year when poorly installed and exposed to insects and moisture, and I have friends with inverters that I sold them more than 20 years ago that are still working well.

The biggest influence on inverter life is temperature—high temperatures will mostly impact the capacitors, which are usually the lowest-lifetime-rated components used in an inverter. Transformers usually will have a much longer life expectancy depending on their construction and operating temperature, so the life expectancy of transformerless, ungrounded inverters will not necessarily be higher. Since grid-tied inverters are typically designed to operate at very high efficiency levels, the electronic components usually do not operate at the temperature levels that are common in other power electronic applications (such as motor drives or power supplies), where efficiency is not as critical. This allows the components in a grid-tied inverter to be longer-lived.

Typically, grid-tied inverters do not operate 24 hours a day; they usually are “live” only about 12 hours a day, and often operate at high power levels only for a few hours. This helps extend their life expectancy. Grid-tied inverters also do not need to “surge” to start motors, so they have a pretty easy life compared to off-grid inverters, which are used with batteries and operate 24 hours a day, and are frequently subjected to overload conditions.

Some of the newer inverters (such as small microinverters) use special capacitors made for solar applications, which extend the lifetime of the inverter to better match the life expectancy of the solar-electric modules they are connected to. How much longer the life will be extended is uncertain, and we won’t really know until they have been operating for a long time, but several companies are offering warranties of up to 25 years.

Christopher Freitas • SunEPI

Comments (4)

Fred Golden's picture

It is sort of difficult to predict how long a new item will last. Afterall these designs have been around for only a short time, so perhaps the longest lasting grid tied inverter was based on a 1990 design that has been improved vastly, and thus not subject to as many failures per 1,000 inverters produced as the 20 year old models suffered.

So while a 1990 inverter might last to the current day (25 years) one designed and put in service in the past 5 years might last many more than 25 years due to improvements made to components that failed in those early inverters.

Charles Culp_2's picture

Hmm, my off grid Trace 4024 has served me well since 1993 on Roatan Bay Islands, off the coast of Honduras. Average temp is 83 and doesnt seem to bother it. Started with 8-90 watt panels and just added/replaced assorted over the years add-0n with 10-305 panels. Have changed the charge controllers with outbacks but pretty much the same config all this time for a 4600 sq ft 3 story home overlooking the sea. Would not change my Trace inverter, it just keeps working.

Sam Vanderhoof's picture

Our company has been in the inverter repair business for several years now. While it is true that temperature kills inverters, it is also true that the early designed grid tie inverters were not robust enough to handle the demanding power requirements and harsh outdoor conditions. Most all of the early inverters carried a five year warranty and we're seeing most of the failures after 10 years of life.
Sam Vanderhoof, Solar Cowboyz

Alberto Marty's picture

In 2000 I installed a Trace SW2500 inverter for my battery solar energy system. No problems up today.

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