Solar Inverter Reliability

[mikrometric]

Anyone got views on the best inverters as far as reliability is concerned.

All appear to offer 5 year warranties but only Mastervolt seems to offer up to 20 years (at a price). Others seem to not offer extensions or 10 years max. This doesn't show great confidence in their kit.

This equipment seems to be the weak point of any pv installation. I don't think most clients would be impressed if told that they would probably have to buy one or two new inverters for their 4kWp system at ~£1,500 a pop (plus installation costs) in the next 25 years!

Are transformerless inverters inherently more reliable?

Does underrating improve reliability?

Which brands and types do you guys reckon for 2.5 to 4kWp arrays?

 

[ExArmy]

i can't tell you any detailed info about this, but a to a renewable energy forum i went to last week they were taliking about a new range of PV kit that had one inverter for each panel, and the seperate inverters were about £300 each. so instead of 5 panels and one £1500 inverter you would have 5 panels and 5 inverters, the idea being that if one was to fail it would be much cheaper to replace and the other 4 panels would keep generating power and making you money

 

[SolarCity]

Cheaper to replace? Not once you have erected scaffold and paid out a days wage for two men.....

SMA and Fronius all offer extensions to their warranty. By the way, just because something only has a warranty for 5 years (still a pretty long warranty) does not mean that it is going to fall to bits every five years.

 

[claypole]

Yep, totally agree. SMA extended warranty for SB3000TL or 4000TL (and all inverters up to 4kw nominal power), as has been posted somewhere here, is 300E for each 5 year period after the initial 5, up to an extra 15 years - see
http://download.sma.de/smaprosa/dateien/2580/B-GV-ZEN110415.pdf

I think that's reasonable given the purchase cost and if they were designed to fall apart after 5 years I don't think they could afford to offer warranty at that price. Again as posted somewhere here, a "fall apart" type failure is likely to materialise well inside the free warranty period if not the first year. For a general wear and tear period of failure I'm not qualified to say but I guess it depends very much on the operating environment and how hard it's being worked.
Note however that for the next 5 year extension period, ie total life 20 -25 years, the warranty price suddenly jumps 200% to 900E. Does this perhaps give a clue?

 

[TedM]

When the FiT rates were calculated by DECC they allowed for the cost of a single replacement inverter over the 25 year life of a system. But most owners are not going to factor that into their payback calcs.

 

[claypole]

And correct me if I'm wrong but I don't think MCS or REAL compels accredited installers to factor this cost into the predicted savings included in their quotations!

 

[Morgan keith]

The guy (who was very clued up and an actual installer) who ran the PV course I attended said that if an inverter is going to break down, it will most likely occur within the first 5 years. After that, an estimated 1 in 20 inverters will fail within the next 20 years. I am however unsure as to where he got these numbers from, but I would say he had a reliable source

 

[SRE]

No-one knows how long the inverters will last they're improving all the time. I explain it to our customers as similar to the expectation of replacing a pump on a central heating system during the lifetime of a boiler. In 10 years time the cost of inverters will have dropped substatially as a result of economies of scale and smarter manufacturing processes. It's unlikely that a customer will be paying £1500 in today's terms for inverters. Remember the £1500 pc packages - not so long ago ....and they may not even need to replace it.

 

[edexlab]

Generally the Inverter failure is down to the varistors and electrolytic capacitors used which wear with age like most electronic equipment , I went to SMA earlier on in the year and this subject was discussed at length, they said If installed in the correct conditions
they can definately last upto 20 years plus but they acccepted that some won't, which is why they offer the warranties available Nb if an inverter fails say in any year under extended warranty for example 15 years after installation then you will get a replacement of the same age or younger and you have the option of having the original back if it can be repaired or keeping the replacement

By the way was commisioning a tripower yesterday all appeared to be working except for the display rang them up tried a couple of things they instructed ,but no joy, its a communication processor fault , anyway they 've sent a replacement from Germany which will be here tomorrow . Have to say I'm impressed with the way they dealt with it ,I've had similar problems with other manufacturers over the years and they just wanted to fob you off and try and blame the installer but I liked how Sma did'nt do this and actually had someone
call back who knew exactly what they were talking about within 5 minutes of contacting them .

 

[mikrometric]

Thanks for the replies. Like I said, extensions are available - at a price!

Power One (Aurora) offers the usual 5 year warranty but also states the design life is 25 years.

Any views on my other questions:-

Are transformerless inverters inherently more reliable?

Does underrating improve reliability?

Which brands and types do you guys reckon?

 

[edexlab]

Generally the Inverter failure is down to the varistors and electrolytic capacitors used which wear with age like most electronic equipment , I went to SMA earlier on in the year and this subject was discussed at length, they said If installed in the correct conditions
they can definately last upto 20 years plus but they acccepted that some won't, which is why they offer the warranties available Nb if an inverter fails say in any year under extended warranty for example 15 years after installation then you will get a replacement of the same age or younger and you have the option of having the original back if it can be repaired or keeping the replacement

By the way was commisioning a tripower yesterday all appeared to be working except for the display rang them up tried a couple of things they instructed ,but no joy, its a communication processor fault , anyway they 've sent a replacement from Germany which will be here tomorrow . Have to say I'm impressed with the way they dealt with it ,I've had similar problems with other manufacturers over the years and they just wanted to fob you off and try and blame the installer but I liked how Sma did'nt do this and actually had someone
call back who knew exactly what they were talking about within 5 minutes of contacting them .

Sma delivered the inverter on time and there was no problem changing it ,even came with straps to secure the box only thing i had to do was swap the lids over as it came with lids designed just for transportation, they also arranged for pickup

 

[SRE]

Worth paying that bit extra for I reckon. we don't stray far from SMA and Fronius just in case we need that sort of backup.

 

[pme]

A point to consider re, microinverters (1 per panel) is that they avoid problems with panel shading causing reduction of the output of the whole string

 

[SolarCity]

A point to consider re, microinverters (1 per panel) is that they avoid problems with panel shading causing reduction of the output of the whole string

As far as I can see, this is their only benefit. And the site needs to have serious shading issues before they become viable.

 

[andyemms]

I have been using SMA SunnyBoys for the last 6 months, from what I have been told and what seems to be an industry wide opinion, they are the best!
Have been told the High Frequency inverters should last the distance....

 

[solarsparkie]

we use and sell danfoss , good old fashioned engineering they weigh in at 35kg and arnt small , of course capacitors have mtbf but having said that heat is also the enemy of electrical components so efficiency and cooling will be an issue with any inverter, when the going gets tough every 10 degrees of heat will reduce expected life by 50% . If your young enough probably worth starting a repair business up 2021

 

[series530]

As far as I can see, this is their only benefit. And the site needs to have serious shading issues before they become viable.

I'll be publishing some data in the near future with regard to shading and micro inversion that may be of interest. It may also show that the shading arguments are not as clear cut as many people think.

I cant do it now as I am away on a business trip but, hopefully, at the weekend, I may have something to offer