<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Friends:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have inherited an off-grid install gone wrong. This is a mini-grid with Sunny Islands and Sunny boy inverters. All of the PV is connected in AC coupled mode. There is no direct DC battery charging through a standard charge controller. Is there any downside to this?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thinking through possible scenarios, I see a problematic situation: The generator is out of order and the batteries are depleted. The loads are all turned off to allow the batteries to recharge, but the battery voltage is so low that the Sunny islands will not start up. Therefore there is no grid and therefore the Sunny Boys will not start and provide PV.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Is this scenario valid? Any other “gotchas” I have not described?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks again to all of you out there. It seems my work flow is such that I come up with a quantity of questions all at once and I feel bad I am periodically loading the forum. I always try to research and think these things out before I come to the group. I found this and it seems to reinforce my suppositions above: <a href="http://www.solarindustrymag.com/digitaleditions/Main.php?MagID=3&MagNo=54">http://www.solarindustrymag.com/digitaleditions/Main.php?MagID=3&MagNo=54</a> I think the bottom line is that the most reliable system will have a majority of the PV AC Coupled with have a modest RE component DC coupled.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sincerely,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>William Miller<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>