[RE-wrenches] BAD choice for Sunny Island
Tump
tump at swnl.net
Sat Jun 17 06:50:24 PDT 2017
I guess this would be me, I am a BIG fan of SMA BUT….. using a SMA SI AC coupled system is not the best idea here. This set up unfortunately will only recharge the batteries when the SOC goes below 70%. 70 % SOC is NOT how one wants to operate a remote power system. Additional cost of the SB + its 220 VAC requirement is not worth it but putting that $$$ into the Exletec is. Building container power requires reliability, DC coupling is just that. Isolated from AC while it can be noisy using MPPT CC, PWM CC are a lot quieter. Morningstar would be first choice as they are available and can offer some trick relay logic if required. In the event that you really need reliable power, I would suggest the;
“ http://exeltech.com <http://exeltech.com/> Exeltec, MX Series Inverters are the world’s first truly redundant, modular inverter system; the most reliable inverter system available. Inverter systems up to 20KW at 120 Vac single phase, 40KW at 240 Vac bi-phase or 60KW at 208 Vac 3 phase are available."
These folks are really great to work with will do pretty much anything you ask for. These inverters will auto swap inverter cards to maintain constant power. Inverter modules are easily shipped and swapped. DC coupling will address the battery charging. I don’t believe that Exeltec has a battery charger they might now. Iota certainly does manufacture one. I used this set up quite a bit when I was doing remote repeater installs. TUMP
> On Jun 16, 2017, at 7:55 AM, Chris Mason <cometenergysystems at gmail.com> wrote:
>
> To my limited mind, the whole 120V sunny island setup is a disaster. Why not install a DC coupled 8KW Outback Radian and solve all your problems. USe any 240V generator, although finding a 2 wire start gasoline unit may be hard. I would use a Nexus controller generac propane generator with propane tank, all mounted on the container. I would never design anything to use gasoline, it's too dangerous.
>
> On Fri, Jun 16, 2017 at 7:19 AM, Matthew Sirum <matthewsirum at gmail.com <mailto:matthewsirum at gmail.com>> wrote:
> Greetings August,
>
> Great thoughts and comments from Brian! I would also suggest speaking
> with the generator manufacturers' tech/engineering folks regarding the
> 120VAC configuration and to confirm 2-wire start set up once you have
> a brand and model or two in mind. Generator parts and service
> availability in the region of the project may also drive brand
> selection. If you need to maximize the inverter's battery charging
> capabilities (depending on battery system charging requirements) you
> may end up needing to look at generators in the 7.5 kW to 8.0 kW
> capacity range to allow for headroom in generator output loading.
>
> Also; I am curious how you arrived at an AC coupled design for this
> project. I do not know any of the details or specific projects goals
> you are working with, but I would potentially consider a DC coupled
> system design... DC/DC charge controller(s) would keep the battery
> system charged (and any DC loads operable) even if the Sunny Island
> and/or Sunny Boy(s) have a failure or is taken offline. If most of
> the AC loads are 120VAC I would consider keeping the inverter AC
> output circuit 120VAC and install a dedicated transformer solely for
> the 240VAC load.... Or perhaps consider a 120/240VAC inverter model.
> Depending on the overall situation a DC coupled system could be more
> resilient. The dedicated transformer for the 240VAC load could also
> potentially help make the system more robust. Also; I have spoken
> with a number of folks who have told me they wish the Sunny Island had
> more/better features for generator integration. I'd like to hear more
> from those who have plenty of experience designing and installing
> systems with Sunny Islands and generators to learn what the current
> thoughts and issues are.
>
> I hope some of these thoughts may be helpful.
>
> Best regards,
>
> ----MATT
>
> Matthew Sirum
> P.O. Box 1227
> Greenfield, MA 01302-1227 USA
> phone: +1.413.773.0611
> email: MatthewSirum at gmail.com <mailto:MatthewSirum at gmail.com>
>
>
> -------- Original Message Below --------
>
> [RE-wrenches] Generator choice for Sunny Island
> August Goers august at luminalt.com <http://luminalt.com/>
> Thu Jun 15 09:02:41 PDT 2017
>
> Hi Wrenches, especially those of you who work on off-grid projects,
>
> We have an upcoming off-grid project where we will be powering a storage
> container with electronics in it. The loads are mostly 120 volt but there
> is a 240 volt heat pump that might occasionally run. We’re AC coupling the
> Sunny Island with a Sunny Boy PV inverter. So, we’ll be installing a
> Outback PSX-240 autoformer to bump the Sunny Island’s output from 120 to
> 240 volt.
>
> We need to select a generator for backup. We need a two-wire electric start
> (in order to be controlled by the Sunny Island) and preferably a generator
> that is okay just running 120 volt loads since the Sunny Islands input is
> only 120 volt. Something in the 3 kVA -7 kVA range should be fine.
>
> Does anyone have experience or ideas about what kind of two-wire start
> generator we might select?
>
> Thanks,
>
> August
>
> Luminalt
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> --
> Chris Mason
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