<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"></div><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hi Mac,</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Yes, I considered using a pilot relay - it makes sense to run it on 120V because relays are readily available. I had the exact same concern - more to fail. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">In this scenario, the inverter/battery room is remote from the house so there is only one load I can switch easily with a contactor, and that's the whole house load. Otherwise, I would definitely consider switching non-critical loads in a low battery situation. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">It just seems prudent enough to use the integrated Battery Preservation Mode (BPM), even in this AC coupled system. I considered a small DC array to charge the batteries in a heavily depleted situation, but it's a 60kWh battery so I would need a pretty substantial "backup" array I think. It does not seem like a reasonable solution. I would expect BPM to do it's job and keep the batteries from reaching a state that they are not recovered quite easily.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jason</div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><b><div style="text-align:center"><br></div></b></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 21, 2021 at 2:37 PM Mac Lewis <<a href="mailto:maclewis1@gmail.com">maclewis1@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hi Jason,<div><br></div><div>The only reason to load shed, without using the internal preservation mode is if you have certain loads you'd like to keep on longer than other loads that you shed. The various preservation modes can be complex, especially if you are AC coupled, so you really have to think through your strategy.</div><div><br></div><div>You can always use a pilot relay, with a coil rating that suits your needs, and then feed the 100A contactor with that. Unfortunately, its just one more piece to fail...</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 21, 2021 at 12:13 PM Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div style="font-family:arial,helvetica,sans-serif">I just learned from the manufacturer that the mercury displacement relay's coil is rated for 43.2 to 52.80V. Obviously, the battery voltage can exceed 52.8 pretty significantly. Does the Sunny Island regulate the output voltage on this relay to 48V or is the actual battery voltage passed through on this terminal?</div><div style="font-family:arial,helvetica,sans-serif"><br></div><div style="font-family:arial,helvetica,sans-serif">The more I read about this load shedding strategy, the more it seems overly complicated. It's also another thing to fail. If the N.O. contactor coil fails, the loads to the house are going to lose power. That's not good for a remote installation. I guess you have to weigh battery protection with how critical the loads are.</div><div style="font-family:arial,helvetica,sans-serif"><br></div><div style="font-family:arial,helvetica,sans-serif">I'm wondering why the internal Battery Preservation Mode isn't sufficient enough. What's the purpose of load shedding if the BPM does effectively the same thing. I can see perhaps shedding some parts of the load and that is a nice feature, but to protect the batteries, why isn't BPM enough?</div><div style="font-family:arial,helvetica,sans-serif"><br></div><div style="font-family:arial,helvetica,sans-serif">Jason</div><div style="font-family:arial,helvetica,sans-serif"><br></div><div><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><table border="0" cellpadding="0" cellspacing="0" style="font-family:"helvetica neue",helvetica,arial,sans-serif"><tbody></tbody></table><b><div style="text-align:center"><br></div></b></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jan 19, 2021 at 8:48 PM Mac Lewis <<a href="mailto:maclewis1@gmail.com" target="_blank">maclewis1@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hi Jason,<div><br></div><div>I have done this with mercury displacement relays:</div><div><a href="https://mailtrack.io/trace/link/ff30c111d75d78887f17a5ed3e3b04bfe2cd428a?url=https%3A%2F%2Fwww.mdius.com%2Fmercury-relays%2Ftwo-pole-relays-contactors%2Ftwo-pole-100-amp&userId=1613865&signature=0abdef13355136e0" target="_blank">https://www.mdius.com/mercury-relays/two-pole-relays-contactors/two-pole-100-amp</a><br></div><div><br></div><div>They do have a 100A 2P 48V coil relay. They seem to work perfectly.</div><div><br></div><div>Good luck</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jan 19, 2021 at 2:51 PM Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">Does anyone know where I can get a load shedding contactor described in SMA documentation for use with a multi-function relay in a Sunny Island?<div dir="auto"><br></div><div dir="auto">Thanks,</div><div dir="auto"><br></div><div dir="auto">Jason Szumlanski </div></div>
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