<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="margin: 0px;">Hello Esteemed Wrenches,</div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">I have a prospective client who has an old GTBB system using a Trace SW -- it was permitted and signed off by the utility way back when and has been operational ever since. It's a Trace SW 4024 that's feeding the grid through a Trace T-240 transformer -- I didn't see a GTI. All he wants me to do is replace his failing array (which would increase his array size from 1152W to 3300W) -- not pull a permit, not change the BOS other than to add a 2nd charge controller.</div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">The original question that lead me to write this post is whether the SW4024 can handle the full 4kW sell-back onto the grid -- I couldn't find any specs on that on the web. </div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">But the question I have now is whether the Trace SW is UL1741 compliant. I didn't think to do an anti-islanding test before I left the site. If it's not, then I'm thinking maybe I should insist that he change out his inverter for a modern one, or I'll pass on the job. If it fails an anti-islanding test (which I'll do next time I'm in his neighborhood), then the dangers are obvious, and I don't want the liability.</div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">What would you all do in this situation? Do any of you have experience with grid-tied SWs -- any advice?</div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">Thanks,</div><div style="margin: 0px; min-height: 14px;"><br></div><div style="margin: 0px;">Russ</div><div apple-content-edited="true">
<div style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><b><br class="Apple-interchange-newline">--</b></div><div style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><b>Russell Mueller</b></div><div style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; 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