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MM5000 grid-tie converter information

Discussion in 'Photovoltaics' started by Gymmy Bob, Oct 17, 2004.

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  1. Gymmy Bob

    Gymmy Bob Guest

    Does anybody know or have experience with this unit? Apparently the
    manufacturer discontinued them and there was some problems with the larger
    MM5000 5kW units.

    Any info would be appreciated.

  2. Tom

    Tom Guest


    MM5000 (mm stands for MultiMode), 5kw units were made by Advanced Energy
    Inc, which went bankrupt in the fall of 2003. The intellectual property of
    Advanced Energy was purchased by Beacon Power and some of their key people
    went there. See

    Beacon Power now makes the M5 inverter based on the old MM5000, but they are
    much better. I have two of the first production runs of the M5, and have had
    no problems since they were installed last Feb.

    I have a 10kw system. I started with 2, MM5000 inverters. The 1st set burnt
    up (no kidding, fire in the garage!). They were replaced by Advanced Energy
    under warranty, and the 2nd set ALSO burnt up. Finally, I put in two M5's
    after Beacon Power took over, and I've had no problems since.

    I have 64, 160 watt panels, 2 M5's and a battery backup system with 8
    batteries, all grid tied and am using net metering here in CA. If you have
    any specific question, let me know.

  3. Gymmy Bob

    Gymmy Bob Guest

    Was the problem with them only the heat or did they have circuitry problems
    also? It looks as if the M5 has only been improved by more ventilation.

    Why did you use two or was it for the 240V matching only? Do you think they
    interfered with each other causing misfiring?

    Thanx for your reply.
  4. Tom

    Tom Guest

    I have to use two inverters since I have a 10kw system, and each M5 is only
    capable of 5500 watts. When I expand my system, I'll have to add a third

    Yes, the air flow is improved, but the circuitry was the problem, although
    the new M5's run cooler than the MM5000's did. They both failed on cool
    days, it was not a heat related problem. The ambient temperature of the
    garage those days was around 75 degrees F. They had no problems in the
    summer when it was 90 degrees plus in the garage and they did not fail
    during the peak heat of the summer (August/Sept).

    One of the failures was power feedback thru the batteries because of poor
    components not blocking the power path. The 2nd one was the failure due to
    components handling way more current than they were capable of handling
    (same reason as the 1st failure, but not the same catalyst - that's why it
    took longer for the 2nd one to fail).

    BTY... I'm a software engineer, and my wife is a hardware engineer, so we
    have a pretty good idea of what was going on (better than the factory since
    we were monitoring the inverters 24/7 and even pointed out to the factory
    several of the failings of their system).

    The new Beacon Power M5's have been working with no problems, so I'd say
    they fixed the Advanced Energy's problems.

    I'd say this. If you ran one of the Advanced Energy MM5000 inverters without
    a battery system, you might be ok (that's just my opinion). Our problems
    were all tied to the inverters not properly handling the battery backup
  5. Gymmy Bob

    Gymmy Bob Guest

    How could the power feedback into the batteries? This sounds like the power
    FETs (I understand they use them) must have been turned on prematurely so
    that grid power fed backwards causing an overheat problem??? If this is
    true it sounds like a tuning problem with the control circuits. Does this
    sound reasonable? I am guessing without ever seeing a unit or schematics, or
    software control. It would be a complex problem to diagnose. Apparently it
    was for them too...LOL

    Which brings me to ask. Do you have schematics or the software to
    interrogate these units you could share? The reason is I am considering
    purchasing a MM3000 unit which, I am told, didn't have the problems
    associated with the MM5000...sales job?...Maybe. Any further info would be
    appreciated, especially about the MM3000 unit.

    Thanx again.
  6. Tom

    Tom Guest

    The batteries (8 total) were originally set up to charge/discharge all
    batteries from both inverters. This is a parallel circuit arrangement. The
    batteries were in parallel with the inverters. This allowed all of the back
    up circuits (6 total circuits) to have available all of the battery power
    and keep the back-up load balanced. It was considered a feature and one of
    the reasons I bought the system.

    But this was also the means to have the current back feed through the
    battery charging circuitry. After our first inverter fire, while the
    factory representative was out at our house my wife noticed that there was
    back feed this way. The batteries were "charging" with a negative current!
    The company immediately issued an edict stating that the in-parallel
    circuitry be discontinued to ALL their inverters with battery backup and
    corrected in those where it was installed that way. Now they are in series
    off of each inverter (4 batteries per inverter) and the two battery banks
    are NOT connected. (I don't like this setup because I have 1/2 the power
    available to my circuits and I now have to calculate my load on the
    batteries and balance the circuits accordingly - meaning move circuits from
    one battery bank to another to balance the load when running on batteries).
    I get the feeling they didn't test this scenario very well - two inverters
    powering 1 battery bank.

    The components just were not capable of handling the current that was
    passing through them. We have pictures of the charred circuitry and melted
    components that we took before the units were removed. On partly cloudy
    (more reflective sun light), cool days (low 70's around here) the PV panels
    and inverters are capable of higher output. That may have been a
    contributing factor because the components were highly stressed over time
    and it was not a hot day on which they failed either time.

    Beacon's website states explicitly that they do not support the Advanced
    Energy products because they had design problems which have now been
    corrected with Beacon's M5 product. The MM3000 was listed in that context.
    I have no schematics or software for it either.

    My opinion: I would not buy any Advanced Energy Inverter product, myself. A
    potential fire is not worth any "deal" on the product. But your experience
    may vary from mine, just keep a fire extinguisher handy :)
  7. Gymmy Bob

    Gymmy Bob Guest

    I don't really understand what the batteries in parallel had to do with a
    backfeed. It sounds like there was two problems in your estimation, the
    parallel batteries, and the capacity of the inverter was not sufficient for
    it's max load setting/ventilation.

    This also sounds like a few power diodes could solve this problem so that
    both inverters can draw off both batteries but never back feed to each
    other. Are you an electronics/electrical tech type guy or only a user of the
    system? This could be a fear factor of interfering with an expensive system
    and may not be practical while any warrantees are on or perhaps even your
    wallet is at risk.

    Thanx for the info.
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