Researchers in Switzerland have been keeping an eye on a bunch of old solar inverters and power optimizers to see how they are faring; with some interesting results.
Solar panels tend to steal the limelight, but the real workhorse of a PV system is the solar inverter. This device takes all the DC output of the panels and converts it to AC for use in the home and export to the grid. It carries out this task day-in, day-out under all sorts of challenging environmental conditions.
As it’s the component under the most strain, the inverter is also the one most likely to fail first. Buying cheaper good quality solar panels is fine, but cutting corners on inverter quality can lead to disappointment down the track.
While 25 year product warranties for solar panels are becoming increasingly common at the cheaper end of the spectrum, standard inverter warranties tend to be far less generous even among the top-end brands. For example, a top quality inverter brand is Fronius; but Fronius inverters only come with a 10 year product warranty (5 years full + 5 years parts only).
So, how long do inverters last generally?
The Answer: It’s Complicated
Boffins at Switzerland’s Bern University of Applied Sciences have been seeking an answer to this question.
Their research incorporates 1,195 PV systems consisting of 2,121 inverters and 8,542 optimizers installed in Switzerland. An optimizer is a type of Module Level Power Electronics (MLPE), aka Panel Level Optimisation (PLO), device added to one or multiple solar panels in a system to maximise panel output. These devices are used in addition to a string inverter. Not all systems in this study have optimizers.
Most of the inverters part of this research were from the following brands:
- Fronius
- Huawei
- Kostal
- SMA
- SolarEdge
- Sputnik
With Fronius, SMA, SolarEdge and Huawei inverters among the most common, it was going to be a case of a rising tide lifting all boats. As for Kostal and Sputnik inverters, this is the first I’ve heard of them.
In a nutshell, what the researchers have determined so far is 65% of the inverters will not have a yield-relevant fault by their 15th year of operation. Furthermore, some inverters may have been replaced while they were still functioning properly; e.g., when a system was upgraded. In this study, such a scenario counted as an inverter failure.
Among their conclusions, the researchers noted time-to-failure (TTF) was dependent on various factors aside from general manufacturer quality1. For example, outdoor installations had a shorter TTF than those installed indoors2.
Power Optimizers And Time-To-Failure
Another interesting finding was in systems where power optimizers were used, the first fault generally occurs earlier than in PV systems without power optimizers – so some failures were likely not inverter-related per se. While optimizer warranties tend to be significantly longer than inverters, in the case of a failure it needs to be replaced and that’s a hassle. The study mentions overall reliability of a PV system increases significantly with a reduction in the number of power electronic components.
The oldest inverters in the study are from the early 1990s, but most were commissioned between 2008 and 2013. 2008 is ancient history when it comes to solar power3, and inverter/optimizer technology has evolved since then4.
The study certainly has its limitations, but it indicates if you choose a good quality inverter, it should last well beyond the product warranty period.
A copy of the study – “Life Expectancy of PV Inverters and Optimizers in Residential PV Systems” – can be requested here. We had to ask, so you do too; lest we are berated by Swiss researchers .
Related: Help! My Vintage Solar Inverter Has Finally Failed.
Footnotes
- The researchers note: “The differences between the TTF varies thus remarkably between different manufacturers.” ↩
- One of the best actions you can take to maximise an inverter’s life is to install it out of direct sunlight. In fact, it’s often a warranty requirement ↩
- Trivia: By 2008 in Australia, only 22,187 solar systems had been connected to the grid. By the end of last year, the figure had skyrocketed to more than 3.3 million. ↩
- For example, back in 2008 transformer-based inverters were very widely used. That has since changed to transformerless devices ruling the roost. ↩
About Michael Bloch
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Hi,
Our SMA Sunnyboy is coming up to 13 years. It’s generated almost 29,000kWh (~23600kWh exported) in 52500 hrs. Hopefully it will last until PFiT ends next year. Certainly paid for itself, panels, batteries, etc, etc, etc (Yul Brynner fan).
b0b
That’s awesome to hear Bob, IV been selling SMA for nearly 15 years in varying capacities (fortunate to be the sales director for SMA now) and hearing feedback like this cements why I love working for a world leader like SMA.. keep on collecting those sun rays…
Hi Ben. I live in Massachusetts and installed twenty 150 watt solar panels on my roof in 2004. I am currently on my third SunnyBoy inverter. The first one died after two months. The second one lasted less than 5 years. The third one is still functioning, but it is starting to have issues. When it finally fails (and I expect that it will soon) there is no way I will replace it with another SunnyBoy. While I understand that inverters are not designed to last more than 10 years, the quality of the SunnyBoy inverters, in my experience, has been less than satisfactory.
Your lucky we went through 3 sunny boy 3.8 kw inverters our new one was replaced under warranty with reconditioned units the third reconditioned one is still going strong after approximately 7 yrs fingers crossed
R
In 2009 I investigated solar panels and decided they were the way to go. As a result of my spreadsheets, four households also decided to go solar. We all installed SMA Sunnyboy inverters.
The ROI for me was 4 years and they are all still working (I removed mine to install a bigger system).
John
My first solar PV system installed in 2011 is a 1.5kW system. A Eversol TL1500 inverter, still going strong (was supposedly a crap brand). The LCD screen is fading a bit, and the button is degrading (the plastic bit breaking down possibly due to UV exposure and revealing the microswitch), but otherwise still functional.
It has inverted nearly 16,000kWh over 11.5 years. An average of 3.8kWh/day.
They say Sydney would generate about 3.9kWh/kW average over the year. So, should be about 5.85kWh average per day for 1.5kW.
Mine’s at 65% production because it’s West facing, I lose 15% straightaway. The remaining 20% would be related to inclement weather and temperature variation of panels (very hot summers here).
No idea what brand the panels are but they’re still shiny, a couple of minor dents from 1 hail storm (size of peas).
When it dies, I’ll replace it with a 6.6kW panels / 5kw inverter system.
I still have two other solar systems that are working in addition (one system added in 2013 and the last one added in 2018). Three different branded systems all working together nicely with the Tesla PW2 battery all on a single phase. No issues. I’m amazed that they behave with each other.
The worst part was the second system’s Inverter which was supposed to be a good brand (ABB – Aurora One) died within its warranty period (during its 3rd year, just carked it without warning, fortunately it was late Autumn, so solar production was not affected as much if it had gone down in the spring/summer months, if one was to lose their inverter, best for it to happen in winter). Took 2 months for free replacement. The replacement unit is still going good after 6 years. Just goes to show that good/premium brands is not necessarily a reliable indicator.
Hi Michael,
the Sputnik inverter that you say you’ve never heard about before was actually the third largest selling inverter company in Europe before 2015.
The company was called Sputnik engineering AG and was a very high quality Swiss inverter manufacturer based in Biel, which sold their product under the brand name of SolarMax.
They unfortunately built a very large factory in Biel which sent them broke, they were snapped up by a German company and dragged across the border into Germany, they’ve never really recovered since the new owners took over.
I had a 4.905kw Sunpower system installed on 4th December 2014 (which was classified as a large system at the time), with a SolarMax P5000, 5kw inverter, a week after my system was installed to my horror, Sputnik went bust.
Today that system just clocked over 46,000kwh of output and has done so flawlessly since it was first installed.
Going forward, I’ve already enquired about expanding my PV system dramatically with once again Sunpower panels and Enphase micro inverters, and if or when the SolarMax inverter dies on my old system, I’ll replace it with Enphase micro inverters as I feel that the added cost is well worth the added benefits and the old and the new systems will be joined seamlessly by the Enphase controller box and with lots of data flowing everyday about the system’s performance.
I have two Trace inverters that have run faultless for 25 years. They became Xantrex then Snieder.
Ian
I got a 4024 SW Plus Xantrex running now for 22 years flawless. By that time everyone say that I was crazy… Until Hurracain Maria hit the island. My house became a museum, since everyone wants to knowb how the “crazy” got power. Very happy with its performance over the years
Does anybody have experience with Magnasine inverters?
On another subject, I have read that an inverter does not degrade when it is stored, or offline. Degradation occurs only when it is producing power. That is when the heat starts to work on the electronic components.
There don’t seem to be any CEC approved inverters made by Magnasine. As far as I know, they are a US manufacturer and I haven’t heard of them being used in Australia.
It’s broadly true that inverter degradation mostly occurs when they’re in use. But it’s still possible for products to deteriorate while in a box. But for most components, it won’t happen anywhere near as fast as it’s heat and current which is mostly responsible for degradation.
That’s right, the Magnasine plant is in Everett, Washington State, USA. I live in Ohio. This is a fine Web site for the world.
I believe the Magnasine is the top of the line. At least the cost is at the top. The innards have an extra coating for marine service. They offer pure sine wave units. I have one but have never used it. Glad to have your comment about it.
No doubt it will deteriorate with age even if I don’t use it. But given my age, it will probably still be good after my final deterioration.
If it’s still in warranty I suggest taking it out of the box and testing it. This is because a considerable number of warranty claims are for devices that don’t work or have problems from the very start. If it works immediately, that’s a good sign. But if you want to be more confident you can run it for at least a few days.
Good advice.
I am tossing up between a Sungrow inverters coupled with Tigo Optimisers or Enphase inverter. We have shading issues.
The solar company recommends Sungrow inverters as it is a DC inverter. We would like to get batteries later on. He said it is more efficient due to being DC.
Yet this site says to go for Enphase. What say you?
Hi June
While Enphase produces reliable microinverters, I don’t necessarily recommend them over other inverter options. What is best will depend on people’s situations, preferences, and budgets. Enphase is likely to be your best option if you want long-lasting microinverters. Their warranty is 10 years in Australia but is 25 years in North America, which is a good sign. A Sungrow inverter is considerably cheaper and also has a 10 year warranty. Tigo optimisers can reduce the effects of shade but some people decide the benefits of optimisers aren’t worth the cost for their situation.
Whether you get Enphase microinverters, a Sungrow, or any other inverter, you will be able to install an AC coupled home battery in the future. The most well known example of one of these is the Tesla Powerwall 2. If you are not planning to get a battery for a few years I suggest not worrying too much about being ready for a battery in the future because the range of home batteries available could change considerably over that time. I do recommend installing a large solar system now so your will have plenty of solar energy to charge any battery you may get in the future.
I don’t know much about your situation, so I can’t give any specific advice, but if there’s anything you want to ask, please feel free.