Hi Sam - It's been probably 6 or 8 years since I've selected a 3rd party automatic transfer switch, but we used to use Briggs & Stratton products with good results:
https://energy.briggsandstratton.com/na/en_us/homeowners/products/standby-generators/transfer-switches-and-accessories.html At least at the time, these had internal circuitry to do the transfer between grid and offgrid operation with a pre-programmed delay of about 10 or 20 seconds. We paired these frequently with Sunny Islands. Now that the major ESS manufacturers have Microgrid Interconnect Devices (MIDs) for their systems, we don't have any reason to use these. Best, August Luminalt On Fri, Sep 20, 2024 at 7:35 AM Sam Haraldson via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > Wrenches, > > We are primarily a grid-tied solar EPC but like many solar companies have > a long history with small off-grid installations. In the past few years we > have been tackling a handful of large, complex, grid-tied battery-backup > systems (sub 90 kwh) range with some working flawlessly and some plagued > with weekly quirks. A weak link we've found in two of these installations > was our choice to use Generac Automatic Transfer Switches. In order for > this ATS to sense a grid outage and perform its transfer it relies on > circuitry built into a Generac generator as well as a source of 12v power > (typically the generator start battery). > > One of our sites doesn't have a generator at all and the other does, but > the grid sensing circuitry in the ATS is bypassed as we want the Sol-Arks > to be the first-line of power during an outage and not the generator. In > order to accomplish this our electrician designed custom circuitry for grid > sensing which is powered by a separate 12v source, has a 10 second delay, > and flips the transfer switch during an outage placing the loads under the > control of the Sol-Arks. > > Our initial design for these systems did not take into consideration that > a Generac ATS doesn't have its own "brains" to grid sense and since we are > now relying on a small custom circuit and a small external 12v power supply > to act as a key player in an otherwise powerful and robust backup system we > are second guessing our equipment choice. What ATS solutions are Wrenches > employing that we should be considering? > > TL;DR - what are the simplest ATS solutions that sense the grid > (frequency, voltage, et al) and self-switch between backup and grid power > automatically? > > Sincerely, > Sam > > > [image: OnSite Energy] > <https://www.google.com/url?q=https://onsiteenergyinc.com/&source=gmail-html&ust=1677085494759000&usg=AOvVaw2NN36GoM1sjnS4RdC8Svt-> > > SAM HARALDSON > Operations Specialist > (406) 551-6135 > 1515 N. Rouse Ave Bozeman, MT 59715 > Locally owned and operated since 2012 > [image: B Corporation] <https://onsiteenergyinc.com/bcorp> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > 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 > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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