Announcement

Collapse
No announcement yet.

micro inverters

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • micro inverters

    Haven't seen a discussion on these too much. Any opinions or installation tricks or techniques? We wont install yet. Not enough proven record. Seems like they'd get too hot-short life.
    Mike

  • #2
    I think Enphase declares their inverters have something ridiculous like a 126 year Mean time between Failure. But they have like a 15 year warranty on theirs iirc. If I ever get around to doing a grid tie, it's definately something that I will look at.

    Comment


    • #3
      Actually 126 year MTBF is nothing when you get into safety situations - the time span can run much farther out.

      They have simulated that - or so they say. How well was it all done? Who knows. In a few years we will learn better.

      Micro inverters could be useful if there will be partial shading of the array. And of course, the opportunity to pay enphase for access to your own data for the next lifetime.
      [SIGPIC][/SIGPIC]

      Comment


      • #4
        I worried the microinverter MTBF issue for a long time before buying. Lab projections are one thing, but real-world performance in the field was not yet established.

        What sold me on their reliability was their monitoring website which gives access to a portion (albeit a large portion) of their "public" installations. You can spend several days clicking on arrays all over the U.S. involving tens of thousands of individual microinverters without ever encountering ONE that is throwing an error code or down.

        It convinced me that the MTBF projections were realistic. Check it out for yourselves:

        http://enlighten.enphaseenergy.com/all_public_systems
        SHF produces something besides manure!

        Comment


        • #5
          Originally posted by silverhorsefarm View Post
          ........ You can spend several days clicking on arrays all over the U.S. involving tens of thousands of individual microinverters without ever encountering ONE that is throwing an error code or down.

          It convinced me that the MTBF projections were realistic. Check it out for yourselves:

          http://enlighten.enphaseenergy.com/all_public_systems
          Or filtered. Tens of Thousands, 1 year of in service, and no failures reported, is massaged data.
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment


          • #6
            Originally posted by Mike90250 View Post
            Or filtered. Tens of Thousands, 1 year of in service, and no failures reported, is massaged data.
            The earliest installs go back to June of 2008. The sites available to the public are available by the owner's choice, not Enphase's choice, so I don't perceive any filtration.
            SHF produces something besides manure!

            Comment


            • #7
              I've seen where they leave heat signatures on the modules. How does that effect module warranty and/or efficiency? To what degree? IDK
              Mike

              Comment


              • #8
                Solarphobic

                I have Enphase inverters and am so very happy with them. However there is a big discussion on how long the electrolytic capacitors in them will really last. Who knows? But at the last Solar Power convention in Los Angeles I found a European company who is beginnng production of a micro-inverter without the caps. I understood it is to be UL approved soon. When widely available they would be my ultimate choice.

                Comment


                • #9
                  Vaporware till they ship consumer units. (like the solar panels for 5 cents a watt, next year)

                  Likely, they are going to higher frequencies, will have less efficenty (less by 2 or 3 %) and use film or ceramic caps.
                  Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                  || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                  || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                  solar: http://tinyurl.com/LMR-Solar
                  gen: http://tinyurl.com/LMR-Lister

                  Comment


                  • #10
                    Yes it sounds great but don't you have to pay for the service to have that???

                    What sold me on their reliability was their monitoring website which gives access to a portion (albeit a large portion) of their "public" installations. You can spend several days clicking on arrays all over the U.S. involving tens of thousands of individual microinverters without ever encountering ONE that is throwing an error code or down.

                    It convinced me that the MTBF projections were realistic. Check it out for yourselves:

                    http://enlighten.enphaseenergy.com/all_public_systems[/QUOTE]

                    Comment


                    • #11
                      On another site they are keeping track of just the people they know and there have been a few failures though overall pretty good.

                      Like Mike points out - it seems the public data may be filtered. Would not be at all unusual for a company to do something like that. Since they have a monopoly on the data they could easily do so.

                      Russ
                      [SIGPIC][/SIGPIC]

                      Comment


                      • #12
                        Micro-inverters, UL and electrolytic capacitors

                        MTBF is a statistical calculation that has nothing to do with how long a product will last before failing. Neither does it predict failure mechanisms. See the relevant technical paper at Enecsys.com for a very authoritative article on the subject that was published on the Renewable Energy World web site last year. Companies that promote mtbf as a measure of product life should be viewed with healthy scepticism. The only meaningful way to predict reliability is through accelerated life testing to recognized industry standards. UL approval has recently been granted for Enecsys micro-inverters and the company is shipping product. Finally, having read several IEEE refereed papers on failure mechanisms in inverters, nothing would induce me to put electrolytic capacitors on my roof - their lack of suitability for applications in tough environments is extensively documented. I can only assume that companies selling pv micro-inverters with these components in them expect to IPO before the curtain comes down.

                        Comment


                        • #13
                          Originally posted by BobJ View Post
                          MTBF is a statistical calculation that has nothing to do with how long a product will last before failing. Neither does it predict failure mechanisms. See the relevant technical paper at Enecsys.com for a very authoritative article on the subject that was published on the Renewable Energy World web site last year. Companies that promote mtbf as a measure of product life should be viewed with healthy scepticism. The only meaningful way to predict reliability is through accelerated life testing to recognized industry standards. UL approval has recently been granted for Enecsys micro-inverters and the company is shipping product. Finally, having read several IEEE refereed papers on failure mechanisms in inverters, nothing would induce me to put electrolytic capacitors on my roof - their lack of suitability for applications in tough environments is extensively documented. I can only assume that companies selling pv micro-inverters with these components in them expect to IPO before the curtain comes down.
                          well put.
                          We use solid tantalum caps for space use, ultra rigid manufacturing controls, and get nowhere near those published inverter "numbers". And for putting thousands on rooftops, with no failures, either the data has to be filtered, because there would always be a batch of failures for the first month, unless these are being "burned in and temperature cycled" before sale, and that's not mentioned anywhere.
                          I expect in 5 years, there will start being very unhappy people with dead rood top inverters. Heck, 10 years is pushing it for the big GT inverters with lots of cooling options and much milder climate.
                          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                          solar: http://tinyurl.com/LMR-Solar
                          gen: http://tinyurl.com/LMR-Lister

                          Comment


                          • #14
                            so why use micro inverters over a big $2,000 one in a system. I don't have any shade so that is not an issue.

                            Are they cheaper?

                            Comment


                            • #15
                              Originally posted by rollandelliott View Post
                              so why use micro inverters over a big $2,000 one in a system. I don't have any shade so that is not an issue.
                              No micro-inverters cost more per watt. They should only be used where shading or different orientation is a problem. Otherwise they are not justified.
                              MSEE, PE

                              Comment

                              Working...
                              X