Sunny Island 5048 Review

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stephendv
stephendv Solar Expert Posts: 1,571 ✭✭
in Solar Product Reviews & Opinions #1
I've been living with the SMA Sunny Island (I'll call it SI from now on) for a few months now and thought I'd jot down some thoughts about the product.

The system has been: SI + forklift batteries + generator for the last 6 months, and just last week I've added 2.8kW of solar using a Morningstar MPPT charge controller. Photos here: http://www.casanogaldelasbrujas.com/blog/2011/06/26/pv-install-done/

First thing to be clear about is that I'm not using the SI in an AC connected configuration with a Sunny boy, because the losses are just too high for year round use. So went instead for a DC connected morningstar unit.
Another point to note is that this is the 230V EU version not the 5048U US version - although I don't think this matters for much of the functionality.

Let's get down to it.

Things I like
  • 100A power factor corrected charger
  • Built in control panel to change every setting available and to view detailed information about the device. No additional hardware required.
  • Built in battery meter that counts Ah in and out. This works out the box if you're using an AC Sunnyboy system because the SI would be in charge of both charging and inverting all power. But if you're using a third party charger (like I am), then you need to install a current shunt in the battery neg cable so that the SI knows how much charge is coming in through the charge controller. The only additional piece of hardware required is the shunt itself.
  • All programable functionality that has to do with the battery state of charge, uses the internal battery meter to make those decisions. I.e. you always use the SoC to program the relays and never the battery voltage.
  • Three independent charging curves: Boost, Full, EQ. Each curve can be programmed with it's own bulk voltage and it's own absorb time. Basically, the SI uses the Boost curve for everyday charging, then every X (programmable) days it will use the Full curve and again, every Y (programmable) days it will perform an EQ. This is a really neat feature IMO and something that I miss from my charge controller. I'd really like to perform a mini-EQ charge (slightly higher voltage than regular absorb, but not quite as high as EQ) on my batteries every 20 days or so to make sure they reach 100% SoC and mix the electrolyte a bit without having to resort to a full EQ. The "Full" charge curve would let you do that so that you could, for example, charge at 2.5V for 4 hours instead of the usual 2.4V for 3 hours, every 2 weeks.
  • Auto gen start without any additional hardware required
  • Load dependent generator start and boosting of the generator output (Although I think is a pretty standard feature in most inverters these days, except outback ;) )
  • 2 programmable internal relays
  • Built in DC disconnection switch, although SMA still recommend using an external fuse or breaker close to the battery.
  • Data logging and config saving onto a built in MMC card.
  • Communicating with the device using an additional RS-485 or RS-232 comms device and free software available from SMA. They also have an open source communication library for win and linux for writing your own code.
  • The option of AC connecting grid inverters in the future.
  • The option of parallel connecting them into a 68kW cluster when I win the lottery ;)

Annoyances
  • The charger will only switch from float to bulk if the battery SoC is less than 70%. This is really silly IMO and doesn't suit my charging cycle. So basically, if you only cycle 20% of the battery daily, it won't go through bulk/absorb until it hits the "Full" charge timeout (see above), which could take many days.
  • If you've programmed it for auto gen start, then whenever you restart the inverter it will try to start the generator. Not too bad for most people, but I wanted to save as much power as possible while the device was not in use, so would turn it off every now and then - and then would have to watch it start my unreliable generator for a few minutes, just so that it knows that the gen is available.
  • No search mode! There is a "standby" mode which you can use if you have more than 1 SI in parallel, but you can't use this if it's the only inverter. So it's either on (24W self consumption) or off. There is also a time dependent sleep function, so you can turn the inverter off in a certain time window - and that's what I've been using to reduce consumption, but a search mode would be nice.

Missing features
(Things that competing products do better)
  • Only 1 AC input. This can either be connected to the Grid or to a generator, not both. Well you can do both, but then you'll have to install an external contactor in order to do the switching between the too. At least the Xantrex XW and the Victron Quatro series have 2 AC inputs.
  • No split phase output. (For US and other split phase countries) the Xantrex XW offers split phase in 1 unit, whereas you would need 2 SI's to get that functionality.
  • Selling to the grid through the inverter doesn't seem to be as fully featured as the XW. I can't really comment on this functionality because I don't use it and it's not entirely clear how it works from the manual, so best to consult SMA direct if this is a sticking point.
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Comments

  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #2
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    Re: Sunny Island 5048 Review

    :D Northern Spain, about 80kms south of the French border. Photos were taken in early spring when everything was still green.... it's now considerably hotter and drier!
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
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    Re: Sunny Island 5048 Review

    are those homemade mounts with 2 positions? i'd like a closeup on the mounts.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #4
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    Re: Sunny Island 5048 Review

    Yep, they're home made some sort-of-close ups here: http://forum.solar-electric.com/showthread.php?p=89187
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
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    Re: Sunny Island 5048 Review

    thanks. i don't know how i overlooked that in the other thread. chalk it up to a bad day i guess.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #6
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    Re: Sunny Island 5048 Review
    stephendv wrote: »
    • The charger will only switch from float to bulk if the battery SoC is less than 70%. This is really silly IMO and doesn't suit my charging cycle. So basically, if you only cycle 20% of the battery daily, it won't go through bulk/absorb until it hits the "Full" charge timeout (see above), which could take many days.

    I've been able to monitor the SI's charging strategy more closely now and I'll now officially change my opinion from "it's silly", to "it's quite clever" :D There aim is to reduce overcharging by not going into a bulk-absorb every day, and to prevent undercharging by forcing a "full" charge every X days. This is what I've seen the last few days:
    - If the SoC has not dropped below 80%, then the following day the SI will stay in float mode all day.
    - It stayed in float for 2 days straight and on the third day went into Boost mode even though the previous day the SoC was 90%.

    It's still unclear to me why they don't use something like SoC or return amps to end the absorb phase instead of relying on fixed time programming for boost.
    More info on their battery charging strategy here: http://files.sma.de/dl/3491/TECHBATT-AEN114414.pdf but still no clear and exact details of when it chooses to go to float or boost mode.
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #7
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    Re: Sunny Island 5048 Review

    Great Info , Spain , Thanks !!

    VT from CDN
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  • jaggedben
    jaggedben Solar Expert Posts: 230 ✭✭
    #8
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    Re: Sunny Island 5048 Review
    stephendv wrote: »
    First thing to be clear about is that I'm not using the SI in an AC connected configuration with a Sunny boy, because the losses are just too high for year round use. So went instead for a DC connected morningstar unit.

    My impression has been that the AC coupling involves fewer line losses. I guess you are talking about the power limiting feature of the SB-SI interaction? So you're talking about losing PV energy because of this?

    It seems to me that if you're talking about a grid-connected setup with the SI as backup then the SB would be the way to go (then no losses to really worry about). Since you are off-grid the situation is different. (Is this right?)
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #9
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    Re: Sunny Island 5048 Review
    jaggedben wrote: »
    It seems to me that if you're talking about a grid-connected setup with the SI as backup then the SB would be the way to go (then no losses to really worry about). Since you are off-grid the situation is different. (Is this right?)

    Spot on. If you're primarily grid connected with occasional battery backup then AC coupling gives fewer losses because you can take advantage of high efficiency GTIs to sell to the grid. But for typical off-grid home use the double DC-AC-DC-AC conversion losses when using the battery aren't as efficient as direct DC charging.
    The exception to this is if the worst month, with the most loads vs. production, is when solar production is good. E.g. a cabin used only in summer with the majority of loads during the day.
    For most off-grid homes, the worst months are in winter where the most important thing is to charge the batteries as efficiently and quickly as possible.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #10
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    Re: Sunny Island 5048 Review

    Forgot to turn the airconditioner off last night, so this morning the batteries were at 74% SoC. Yet the Sunny Island was in Float charge mode. I thought I'd give them a bit of a boost and also excercise the generator, so turned it on and was surprised to see the SI backfeeding the generator! Turns out the solar charge controller had already taken the batteries above float voltage and the SI was trying to charge at Float, so it backfed the gen. Not ideal.
    I believe there is a permitted reverse power parameter in the SI which should prevent this, so will take a look later.
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #11
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    Re: Sunny Island 5048 Review

    Interesting. Does the SI have the ability to enable selling only when end amps or return amp have dropped below a user specified level?
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