Micro Inverters on not?

bart
bart Solar Expert Posts: 30 ✭
in Solar Beginners Corner #1
I have 2 quotes for basically the same size system at 6000 to 6900 Watts. One is using (15) Enphase D380 and the other is (1) SMA 6000 - Both include (30) 230w Yingli modules.

The price is slightly higher for the Enphase (but less than 2K).

I sort of like the Enphase install as it seems more (1) DIY friendly, (2) there is no single point of failure, (3) It appears to be more easily expandable.

Can anyone give me your thoughts on these two design?

Thanks, bart
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #2
    Re: Micro Inverters on not?

    We have had a lot of discussions about Enphase (see Google search here).

    Short answer, many of us a bit leery of installing a bunch of small inverters under solar panels on the roof and prefer the idea of a single (or pair) of large inverters mounted down on a wall someplace in shade/cool. Just don't know how long the Enphase will last in those conditions and replacing one large inverter on the ground seems easier than pulling panels to replace on on the roof.

    The other issue you may want to look at is monitoring... Enphase charges a bit for each inverter per year to access their website full of your data. You can access the data without their subscription plan--but it may not be very user friendly or very detailed.

    Pretty much your choice... They both will work and they both have their pluses and minuses.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Micro Inverters on not?

    The one real potential plus of an enphase system as I see it, is if any or all of the PV panels are subject to shading throughout the day or year. In the case of some partial shading, the enphase might be better at real world harvesting of power.

    That said, if partial shading, or different facet installation is not an issue, I agree with what Bill says,, advantage single point inverter(s).

    Tony
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #4
    Re: Micro Inverters on not?

    according to this

    http://www.enphase.org/downloads/Enphase_D380_Datasheet_101509.pdf

    Its a maximum of 380 watts AC ... but your connecting 460 watts of PV. Also, hooking up multi-panels to a single inverter is in essence defeating the number one claim of these inverters, that being a panel shaded won't effect the the other since its sold as a one to one solution, not 2 to 1 as you have been quoted.

    If you want micro-inverter, stay one to one and make sure the inverter can transfer all the energy the panels could provide, my guess when you properly configure using the correct inverters ( you need 30, not 15 ) , your looking at more like a 5-7K difference with no benefit unless you have bad shading.

    I'd say go with the SMA, number one inverter manufacture in the world
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #5
    Re: Micro Inverters on not?
    Solar Guppy wrote: »
    Its a maximum of 380 watts AC ... but your connecting 460 watts of PV.
    The Enphase inverters will push out 200W max/inverter. The D380 is the same as the M190, so it will push out 400W max. You are comparing AC to DC watts - as many know in real life it is not common for a panel to push out more than 85% of it's nameplate rating because of heat and installation. How much power will be "lost" to the inverter maximum output will depend greatly on the specifics of the particular install.
    Solar Guppy wrote: »
    Also, hooking up multi-panels to a single inverter is in essence defeating the number one claim of these inverters, that being a panel shaded won't effect the the other since its sold as a one to one solution, not 2 to 1 as you have been quoted.
    See earlier - the D380 is two M190s in one box with beefier wiring. Simplifies the install and lets you install more panels per string. Yes, if one of the two inverters fails, you will have to bring down an additional panel to replace it.

    What will work better for this install will depend on a lot of specifics that have not yet been provided.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #6
    Re: Micro Inverters on not?

    Missed that it was two in one ... Seem like an odd package, they cripple it thermally by having two in a single package so you can have less AC wiring? What happens when one of the two inverters fail?
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #7
    Re: Micro Inverters on not?

    Wonder if it uses single output H-bridge stage with two separate MPPT high voltage DC controlled boosts.
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #8
    Re: Micro Inverters on not?
    Solar Guppy wrote: »
    Missed that it was two in one ... Seem like an odd package, they cripple it thermally by having two in a single package so you can have less AC wiring? What happens when one of the two inverters fail?
    Obviously they have determined that thermals aren't an issue (surface area of one D380 isn't much less than two M190s) and that failure rates aren't high enough that having to essentially replace two units when one fails that it is a cost issue. Does anyone else offers a 15-year warranty standard on their inverters?
    RCinFLA wrote: »
    Wonder if it uses single output H-bridge stage with two separate MPPT high voltage DC controlled boosts.
    From what I can gather from their website the DC inputs are completely independent, while the AC side is partially dependent.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: Micro Inverters on not?

    "Does anyone else offers a 15-year warranty standard on their inverters?"

    so how much do we know of enphase that 5, 6, 7, or whatever years down the road that they won't pull a sanyo on us and change the warranty? even when keeping it in writing at 15yrs they may wiggle out of it or just up and ignore it, aka swwp.
    hopefully this won't be the case, but i have a hard time believing they could offer a warranty that many times bigger than what other quality inverters are getting and yet be under more adverse conditions.

    is my memory failing or did i remember it was initially 20yrs for their warranty?:confused::cry: in any case the pv will outlast it.
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #10
    Re: Micro Inverters on not?
    niel wrote: »
    so how much do we know of enphase that 5, 6, 7, or whatever years down the road that they won't pull a sanyo on us and change the warranty? even when keeping it in writing at 15yrs they may wiggle out of it or just up and ignore it, aka swwp.
    Red herring.
    niel wrote: »
    is my memory failing or did i remember it was initially 20yrs for their warranty?:confused::cry:
    No, the first-gen inverters had a lesser warranty, but Enphase upgraded their warranty to 15-years retrospectively.
    niel wrote: »
    in any case the pv will outlast it.
    PV will outlast any inverter. How long are SMA, Fronius and other inverters lasting in real life? I've heard that failure is common enough in them once you reach the 10-year mark that you should plan on having to replace it within 15 years but have no direct experience.
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