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Thread: Micro-inverters - good or bad?

  1. #1
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    Micro-inverters - good or bad?

    Can I ask whether any one has any experience of micro-inverters in a solar pv system?
    We have been talking to our “favourite” installer over the phone. He’s coming to look at the site on Wednesday. The shed we had in mind for the panels is too small to hold as many as we want/need so the system is going to be a bit complicated to wire up - panels on two roofs, cable put underground between them etc. Also there is some shade in the evening on one of the roofs but not the other. The installer is very keen on micro-inverters to simplify things but I’ve seen some good & some bad reviews of them. The people who like them say they increase the cost but also increase the efficiency; the people who don’t, say they go wrong & are fiddly to replace.
    I need to talk to real people who’ve used them!

  2. #2
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    Re: Micro-inverters - good or bad?

    How big is the proposed system? Not that I've got a clue about micro-inverters I'm afraid but we've got a 30kw system split between two differently orientated sheds. It's basically wired as 2x 15kw systems to separate inverters but then through one generation meter, sounds similar to yours but also completely different!

    Interestingly although it has 15kw facing south and 15 facing west it produces less power (a couple of kw) on any given day than another 30kw system that only faces west. No idea if we're suffering losses with the twin inverter set-up or what but it's not quite what we expected. Still happy with them both though
    Stay in Northamptonshire - meadowviewcottages.co.uk

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    Re: Micro-inverters - good or bad?

    Quote Originally Posted by foxbox View Post
    How big is the proposed system? Not that I've got a clue about micro-inverters I'm afraid but we've got a 30kw system split between two differently orientated sheds. It's basically wired as 2x 15kw systems to separate inverters but then through one generation meter, sounds similar to yours but also completely different!

    Interestingly although it has 15kw facing south and 15 facing west it produces less power (a couple of kw) on any given day than another 30kw system that only faces west. No idea if we're suffering losses with the twin inverter set-up or what but it's not quite what we expected. Still happy with them both though
    That's very interesting. Our set up is going to be very similar I think. We have two options for ours - twin inverters or all-over micro-inverters. I don't know if the length of extra wiring would cause losses would it? On the face of it you'd think it would be more efficient to separate the halves wouldn't you. Our two roofs both face the same way but one has shade in the evening & the other doesn't so we're told it'll work at the lower efficiency of the shady half if it's all wired together. Apart from optimising efficiency, the added advantage of the micro-inverters is meant to be the closeness of them to the panels, so, yeah, at a guess it's maybe a cable length problem? I don't really know what I'm talking about but I'll put it on my list of questions for the guy when he comes.

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    Re: Micro-inverters - good or bad?

    Quote Originally Posted by mongrel View Post
    That's very interesting. Our set up is going to be very similar I think. We have two options for ours - twin inverters or all-over micro-inverters. I don't know if the length of extra wiring would cause losses would it? On the face of it you'd think it would be more efficient to separate the halves wouldn't you. Our two roofs both face the same way but one has shade in the evening & the other doesn't so we're told it'll work at the lower efficiency of the shady half if it's all wired together. Apart from optimising efficiency, the added advantage of the micro-inverters is meant to be the closeness of them to the panels, so, yeah, at a guess it's maybe a cable length problem? I don't really know what I'm talking about but I'll put it on my list of questions for the guy when he comes.
    Whatever you do don't take my example as being a good one though! I agree with the efficiency bit, we expected the split system to perform better than the single inverter system before it was installed. The split system starts the day quicker and can often be 20kw ahead at lunch time, we sit in a bit of a valley though and I wonder if the damper mornings perhaps reduce the gain that the early morning sun produces as a result, meaning the single system makes more use of the evening sun when it's not impeded by due, fog etc? No idea really as you can tell!!
    Stay in Northamptonshire - meadowviewcottages.co.uk

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    Re: Micro-inverters - good or bad?

    Sent this thread to my engineer cousin, coz we both have PV systems (small, by UK standards) & keep tabs on developments.

    He replied :

    "Big coincidence - have forwarded your BFF link now.
    Overall, I think they ARE a good idea - getting away from serial panel
    connections and avoiding DC currents at substantial voltages."

    And FWDed an email he had received almost simultaneously, as below:

    "Stu,

    I have been doing some more research into solar panels and I now like
    the look of the 310W JA Solar Modules with Enphase 250 Micro inverters.

    With this combined a Enphase Envoy to monitor the system via the internet.

    It is more expensive, but with individual Inverters each panel deliver
    220-240 directly to the system. And if one panels goes down, it does not
    stop the system as would happen with all the panels linked to a central
    inverter.

    Then, maybe in a few years, put some batteries in the roof.

    Is this good idea?

    Cheers

    J "

    Make of that what you will.

    JV

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    Re: Micro-inverters - good or bad?

    Thanks very much for taking the trouble. That's very good of you.
    I'll look those up & run it by the man when he comes Wednesday.

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    Re: Micro-inverters - good or bad?

    Quote Originally Posted by mongrel View Post
    Thanks very much for taking the trouble. That's very good of you.
    I'll look those up & run it by the man when he comes Wednesday.
    Hello Mongrel
    I presume it is my post above to which you refer - in which case, no trouble at all. Happy to add some grist to the mill.

    The thing I like to contemplate is that in 36 hours, as the result of a happy (but infinitesimally small) coincidence on the opposite side of the world, you might have some info which could lead to a solution for your problem.

    More power to the BFF

    JV

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