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>
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