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: matthewsi...@gmail.com -------- Original Message Below -------- [RE-wrenches] Generator choice for Sunny Island August Goers august at 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 _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org