what is the longest a grid tie central inverter has lasted?

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rollandelliott
rollandelliott Solar Expert Posts: 834 ✭✭
So I've read over and over again that Central Grid Tie inverters fail after 12 to 15 years.
When they fail what typically goes wrong with them? A blown capacitor?

I'm also curious about there maximum life? What is the longest running residential GT inverter you know of? What made it last that long? I'm guessing an indoor installation helps a lot. Is there anything else that would extend the life of this expensive component?

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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    You could infer some of this from the costs of garantee extension programs. E.g. a 3kW sunny boy costs about 1500 Euros retail. To extend it's garantee from the standard 5 to 10 years costs 180 Euros, to 15 years = 400, to 20 years 575 and to 25 years 1150. There's a big jump between 20 and 20 years, so I'd wager that the manufacturer expects it to fail after 20 years.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    It's simply a fact that electronic components do not last forever. Turning them on and off creates thermocycling; the component heats up, cools down, heats up, et cetera. This makes things mechanically expand and contract which puts physical stress on things. The more cycling and/or greater the change the larger the effect. Run components near to their spec'd limit and they suffer more (current = heat = bad). Even wiring can fail from this action.

    How does this apply to a central inverter? For one thing it turns on every day and off every night. It is run at its peak capacity during the day (hopefully). 365 cycles per year, 3650 in ten years, et cetera. So whereas you may have a radio or TV that outlasts this, that device isn't pushed to its current limit every day. It also probably isn't run for six hours per day (well, in some households ...).

    This is why some of us are suspicious on Enphase's unusually long warranty. They have no "golden components" capable of outlasting others', and their installs are up on the roof where the weather is the worst (especially in terms of temperature change). There are things that can be done to reduce the effect and lengthen life, but such efforts inevitably add to cost (and basically amount to over-sizing components so things are not run near their limit).

    Bill can give a lot more detail on this subject I'm sure.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,469 admin
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    Re: what is the longest a grid tie central inverter has lasted?

    Did not Enphase redesign their newer units to remove the electrolytic capacitors?

    Pretty much what Marc/Cariboocoot said. You have aging from heat (for every 10C/18F increase in temperature, live is cut by 1/2. Run something at 36F or ~106F over 70F ambient, live is cut by 1/2*1/2=1/4 the life). And you have the thermal cycling (for example, jet engines have the number of on/off cycles as a major predictor of the next maintenance cycle).

    Back in the day when 3 1/2 inch 40-100 MByte disc drives were coming out. I would just setup an environmental chamber to cycle from 40F to 112F (or what ever the spec was) and cycle from cold to hot to cold about 4x per day. After about two weeks, 80% of the vendor drives would fail (usually some component would delaminate from the PCB), and 20% would (appear) to work "forever". As the industry improved, I had almost zero failures of hard disks from thermal cycling.

    A lot of people like to say that the computer in their car will last 15 years in the engine compartment. In reality the number of hours that a car operates is not that high. For example, say:
    • 15 years * 15,000 miles per year = 225,000 miles
    • 225,000 miles / 35 MPH typical average speed for a car = 6,428 hours
    • 24 hours per day * 365.25 days per year = 8,766 hours per year

    That is less than a year of operating time for a 24x7 off grid inverter. Or possibly two years of life for a GT inverter or solar charge controller

    In the end, 10 years is a pretty long time for always on electronics and add the daily thermal cycling for high power electronics/switching components, it is difficult (and expensive) to design and manufacture something that will last longer.

    And, it is not that the failures would not be easily repaired or "failure prone"/life limited components cannot be repaired--It is the fact that electronics have been evolving so fast. Miniaturization for anything with a transistor in it means the average production life for a computer/memory component is around 1-2 years. It is simply difficult/expensive/to get spares 10 years later.

    Back in the early 1980's, the top of the line 9" Fujistu Eagle disk drive weighted 150 lbs, cost ~$20,000 in volume, and held ~500 MBytes of data. I was at the office products store yesterday -- a 4 GB USB memory stick for $4.99 or so.

    Moore's Law of doubling of transistor density every 2 year, 25=32x more transistors every 10 years has just made repairing of old electronics, or even providing 20-30 year life components just not worth the time and money.

    Miniaturization has actually really helped to improve reliability. Smaller devices have less physical size which means that thermal cycling has less of an effect. And smaller devices generate less heat.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    This is why some of us are suspicious on Enphase's unusually long warranty. They have no "golden components" capable of outlasting others...
    Actually, they do. The most common failure point in inverters is their electrolytic capacitors, which dry out, corrode though, and/or rupture over time and heat cycles. Most inverters have them, but Enphase micros do not. That's not to say that some other component cannot fail, but that difference is what they are banking on. That said and FWIW, the guys at SMA are skeptical of the long Enphase warranty as well, and I don't think they will be matching it when their micro comes out.
  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    so no ones heard of a grid tie inverter lasting 20 years? maybe they haven't been out long enough?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,469 admin
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    Re: what is the longest a grid tie central inverter has lasted?

    Just saying, save some money. Living off grid has costs.

    If they last 20 years, be very happy.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: what is the longest a grid tie central inverter has lasted?
    so no ones heard of a grid tie inverter lasting 20 years? maybe they haven't been out long enough?

    Those that were built 20 years ago are not the same as those built today. There has been much advancement in inverter design in the past two decades!
    It should be interesting to see what happens in the next 20 years. (Hmm. Might have a bit of trouble with that myself.)
  • rollandelliott
    rollandelliott Solar Expert Posts: 834 ✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    OK thanks for the responses. I'm sure the best data comes from the actual manufacturers, but obviously they are biased and aren't the best people to ask. I'm surprised there aren't any solar installers or 3rd party historical data on this aspect of solar systems.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: what is the longest a grid tie central inverter has lasted?
    OK thanks for the responses. I'm sure the best data comes from the actual manufacturers, but obviously they are biased and aren't the best people to ask. I'm surprised there aren't any solar installers or 3rd party historical data on this aspect of solar systems.

    It's hard to believe, but it is really quite a new industry. :D
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: what is the longest a grid tie central inverter has lasted?
    It's hard to believe, but it is really quite a new industry. :D

    coot is quite right and another aspect that has slowed down the progress of the applications of solar, beyond what nasa needed it for, is the supply and demand aspect. there just aren't as many of us as for pcs, radios, tvs, etc so the pure sine wave inverters are relatively new and slow to progress with most of them at after the turn of the century, but some prior to that too. a few of the pioneers have been on this forum, but i won't tell you that they invented it like al gore did the internet.:p some of those pioneers and others can chime in to comment on the invention aspect, but we can say that nearly all of the inverters prior to 20yrs ago were msw.
  • solarix
    solarix Solar Expert Posts: 713 ✭✭
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    Re: what is the longest a grid tie central inverter has lasted?

    Grid-tied inverters which potentially could be long-lived have only been around now for 6-7 years. I have an old off-grid Heart inverter from 25 years ago that has been repaired (lightning strikes) twice but still works - although I don't use it as it is inefficient and MSW.
    The new enphase finally designed out the e-caps, but I figure the old ones that do will start dropping like flies in a couple more years.
    Modern GT inverters might be pretty rugged, but its the digital circuitry/complexity in them that worries me.