Enphase Micro inverters vs. central SMA Xantrex etc

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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #32
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    The Powerboxes absolutely do not bottleneck the string. They independently max out the production of each panel with high-speed MPPT and transform the power to a voltage and current beneficial to the inverter which is smaller and less expensive because it is only doing the AC conversion - not the DC-DC front stage. It is more involved to install, but worth it being a more robust, efficient system. I do not want the risk of having to replace emphase units one by one as they fail years from now. They save some time installing now but could be a nightmare down the road.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #33
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    I am guessing the solar panels were scrapped. The installer was not very careful in taking them down and the backing was punctured on a few... In any case, from reading a report elsewhere, there was a risk of overheating/arcing failures eventually so nobody should reuse on another installation.

    The GT inverter itself was returned to the vendor (voluntary change out by the vendor due to possible early life failure due to manufacturing issues). It was a 5+ year old inverter and does not meet current code (no neutral voltage sense, old DC/AC disconnect which could fail if switched on/off under full load). Do they reuse some components for warranty repairs? Don't know.

    So far, the system is working probably 10% better than it did before... I have seen a bit over 3,300 watt peak at times (never more than 2,999 watt peak before) and multiple >20 kWH days from the system--Before, I would see perhaps 1-2 >20 kWH days per year. Neither inverter has indicated on the LCD that it was power limiting (don't know if they indicate condition or not).

    The new inverter is 3.3 kW rated vs the older one which was 3.0 kW rated...

    Still very happy and crossing my fingers.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    #34
    Re: Enphase Micro inverters vs. central SMA Xantrex etc
    BB. wrote: »
    I am guessing the solar panels were scrapped. The installer was not very careful in taking them down and the backing was punctured on a few... In any case, from reading a report elsewhere, there was a risk of overheating/arcing failures eventually so nobody should reuse on another installation.

    The GT inverter itself was returned to the vendor (voluntary change out by the vendor due to possible early life failure due to manufacturing issues). It was a 5+ year old inverter and does not meet current code (no neutral voltage sense, old DC/AC disconnect which could fail if switched on/off under full load). Do they reuse some components for warranty repairs? Don't know.

    So far, the system is working probably 10% better than it did before... I have seen a bit over 3,300 watt peak at times (never more than 2,999 watt peak before) and multiple >20 kWH days from the system--Before, I would see perhaps 1-2 >20 kWH days per year. Neither inverter has indicated on the LCD that it was power limiting (don't know if they indicate condition or not).

    The new inverter is 3.3 kW rated vs the older one which was 3.0 kW rated...

    Still very happy and crossing my fingers.

    -Bill

    So basically your original system was recalled due to manufacturing defects?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #35
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    Yep... The panels failed (either 2-3 calls for single panels, or >20% of the panels failed Isc testing and BP would return). Mine failed the >20% bad panels. Took 3+ months to get a new set--but new set I did get.

    The Xantrex inverter had a capacitor recall--but they would have just subsituted out the capacitor/filter board (bad batch of capacitors--lots of that going around--not just Xantrex).

    I never heard the reason my GT unit, already just out of the 5 year warranty was replaced--Mine was working fine. I believe that Schneider is working hard to upgrade the product line--But I have no further information than (from what I had heard earlier) that a manufacturing issue was causing early life failure (when I purchased my inverter it came with a 5 year warranty with an option to pay for another 5 years--a year or two later, it was upped to 10 year). I assume that this inverter will have a 1 year warranty. The new GT inverter also has a huge 3 pole switch (two AC and one DC) to replace the little disk switch it had before (they had to enlarge the base of the inverter to hold all the new parts).

    Other news--Got 22+kWH on my system today--Highest ever in the last 5 years with the "old system" was 20 kWH once or twice per year.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    #36
    Re: Enphase Micro inverters vs. central SMA Xantrex etc
    BB. wrote: »
    Yep... The panels failed (either 2-3 calls for single panels, or >20% of the panels failed Isc testing and BP would return). Mine failed the >20% bad panels. Took 3+ months to get a new set--but new set I did get.

    The Xantrex inverter had a capacitor recall--but they would have just subsituted out the capacitor/filter board (bad batch of capacitors--lots of that going around--not just Xantrex).

    I never heard the reason my GT unit, already just out of the 5 year warranty was replaced--Mine was working fine. I believe that Schneider is working hard to upgrade the product line--But I have no further information than (from what I had heard earlier) that a manufacturing issue was causing early life failure (when I purchased my inverter it came with a 5 year warranty with an option to pay for another 5 years--a year or two later, it was upped to 10 year). I assume that this inverter will have a 1 year warranty. The new GT inverter also has a huge 3 pole switch (two AC and one DC) to replace the little disk switch it had before (they had to enlarge the base of the inverter to hold all the new parts).

    Other news--Got 22+kWH on my system today--Highest ever in the last 5 years with the "old system" was 20 kWH once or twice per year.

    -Bill

    It's great to hear that the manufacturers are backing their products when there are failures.
    How did you test for defective panels?
    I have 26 BP SX 3200 with no problems at this time. Just would like to know what failure symptoms are if they should ever occur.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #37
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    I noticed that on a bright day, my power output was about 1/2 of what it should be... (seemed to drop from normal or a bit below to 1/2 in a day or two). We had months of pretty poor weather and this was one of the first weeks of good weather in a while.

    For my panels, BP-4175 (or 4175A), I believe the installer just measured the short circuit current with a meter on a bright day. They were replaced with BP-4175B versions (new production out of China).

    You could see the failure from the front of the panel... There is a ~3/4" x 3" metal strip right above the junction box under the glass visible under the glass on the face of the panel.

    On mine, some panels had a light brown (coffee stain on paper) haze on/round that strip (I don't know if from heat or from moisture/rust). On panels with more issues (higher resistance/closer to total failure?), the heat from the failing electrical connections appeared to be enough to start delaminating the panel. You could see streaks of "air bubbles" under the glass starting at the J-box strip and radiating outward by 1/2-1" or so...

    Just a guess as to what caused the discoloration/delamination--I did not take the panel apart or get any information from BP.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    #38
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    Thanks for the info Bill.
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  • System2
    System2 Posts: 6,290 admin
    #39
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    There are several problems with micro inverters. First they are typically far more expensive than a central inverter and offer a lower efficiency ratings for poorer power production and a smaller rebate in many states than many central inverters and especially SolarEdge inverters. Second, in a catastrophic nearby lightning strike, because micro inverters are installed in a distributed format, the ac output of each micro inverter is connected directly to the grid. A surge of sufficient voltage could easily take our every micro inverter in every branch circuit and void your warranty which would mean removing all of the solar panel to get to the micro inverters, a very expensive proposition. Third their limited maximum power rating means that you will lose a considerable amount of power production from each solar panel. For example a 240 watt solar panel with a 190 max inverter. No matter how many white papers these micro inverter manufacturers put out, It doesn't make sense. Fourth they typically handle their data communications over the electrically noisy AC lines which provides the potential for communications errors. SolarEdge for instance comminicates over the relatively quiet DC lines and offers all of the benefits of a micro inverter including shade mitigation and individual panel monitoring and it offers a much higher efficiency and higher wattage capacity per panel so you are not wasting power at a lower price per watt.
    thehardway wrote: »
    I wouldlike to hear some opinions.

    I am seeing a lot of statements that single inverter systems have a rather short life cylce (10-15yrs.)

    Enphase is claiming a life expectancy of over 25yrs and a MTBF of 331 years. Sunnyboy and Xantrex say "built for more than 20 yrs under the right conditions" and there are reports http://ecmweb.com/ops_maintenance/photovoltaic-module-maintenance/

    that say 5-10yrs. is the usual time before replacement

    At approx 10-20% of the systems initial cost it seems the invertor should last at least as long as the panels. If it fails it becomes more than 40% of system cost which severely hampers the payback and ROI numbers.

    I am inclined to go with the Enphase micro invertors as they will also allow me to expand modularly in the future as panel and invertor prices drop. I don;t see a huge difference in the cost.

    Why would I want to go with a single central inverter and why are all of the installers quoting systems with the SMA vs. the Enphase.

    I see a lot of you listing Enphase invertors in your systems. What is your experience? Any regrets?
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  • Frxddy
    Frxddy Solar Expert Posts: 113 ✭✭✭✭
    #40
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    Inverterpro.....I guess you missed the new Enphase units..... rated 215 watt, as with the 190 series they will put out some more. 25 year warranty, a real warranty, not some prorated thing that pays you $11 near the end of it's life. And, the efficiency is within tenths of a point of the popular size central inverters. Lightning strikes? You must know more about lightning then I do & I can tell you exactly what lightning will do every time it strikes: It will do exactly what it wants. It's just as likely to take out a central inverter as it is a micro inverter. I would venture a guess it would be near impossible to take out all micro inverters at once....and if it did, it probably just took out the house so call the insurance company.
    Amazing how different people see things from different lights. I looked into SolarEdge before I bought Enphase. They are not only the most expensive way to set up a grid tie system, what if they fail? One responder talked about needing to go up on the roof if an Enphase has a problem, yet fails to notice that the Solar edge are up there too!
    The one thing I like about micro inverters is that they make solar PV installation something that Joe average can do. No worries about bringing extremely high voltage DC off the roof.
    Far more expensive? I don't believe so. I am getting zero state rebate. I am getting zero power company rebate. My self installed thirty panel, 6,900 watt Enphase system with BP panels (25 yr @85%) is under $18,000 after the federal credit. Correct me if I'm wrong but isn't that $2.61 a watt? And...isn't that "cheap"?
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #41
    Re: Enphase Micro inverters vs. central SMA Xantrex etc

    I recently got quotes for 3Kw install with and without Enphase inverters, the Enphase raise the price about $0.25 a watt, slightly more than a central inverter.

    Advantages, simplified wiring and components, Disadvantages, slightly more cost.
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #42
    Re: Enphase Micro inverters vs. central SMA Xantrex etc
    solar_dave wrote: »
    I recently got quotes for 3Kw install with and without Enphase inverters, the Enphase raise the price about $0.25 a watt, slightly more than a central inverter.

    Advantages, simplified wiring and components, Disadvantages, slightly more cost.
    Sums it up nicely. :D I think that demand for Enphase products is still keeping their prices higher. Their latest iteration should reduce the cost somewhat - we will see. Eventually they should be able to get the size of these inverters down the size of a box of cards and they will be integrated into the panel now that the warranties match.
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  • jaggedben
    jaggedben Solar Expert Posts: 230 ✭✭
    #43
    Re: Enphase Micro inverters vs. central SMA Xantrex etc
    Inverterpro wrote: »
    There are several problems with micro inverters. First they are typically far more expensive than a central inverter

    But this difference is small compared to the cost of panels, so it amounts to something like 7% of the whole system at the most.
    ...and offer a lower efficiency ratings... and a smaller rebate...

    That's just plain false.
    in many states than many central inverters and especially SolarEdge inverters.

    Well, that was shameless. We see who you almost certainly work for. (And, that you are not trying to sell a mere central inverter system, but a system with electronic boxes on the panels, kind of like micro-inverters. How do the costs compare, btw?)
    Second, in a catastrophic nearby lightning strike, a surge of sufficient voltage could easily take our every micro inverter in every branch circuit

    This will absolutely also happen to string inverters, and almost certainly to Solaredge equipment on panels too. No sale on that one.
    Third their limited maximum power rating means that you will lose a considerable amount of power production from each solar panel.

    Perhaps, but if you have shading issues then you lose MUCH more from traditional string systems. This is why micro-inverters were invented.
    Fourth they typically handle their data communications over the electrically noisy AC lines which provides the potential for communications errors.
    SolarEdge for instance comminicates over the relatively quiet DC lines and offers all of the benefits of a micro inverter including shade mitigation and individual panel monitoring and it offers a much higher efficiency and higher wattage capacity per panel so you are not wasting power at a lower price per watt.

    Fair enough, I look forward to seeing other technologies compete with micro-inverters. You might want to be a little more honest and sociable in your forum posts, though.
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