<div dir="ltr">If they are the AES 48-6650 batteries I think they do <u>not</u> have low temperature mode, and will be damaged if they are charged while they are below freezing. The AES 48-3000 I think <u>do</u> have a low temperature mode and would prevent charging if they are below freezing. <div><br></div><div>Wind will tend to make any object closer to the ambient temperature, unless there is evaporation involved. So, if there is radiation to the sky making the object colder, the wind will warm it. If there is solar radiation making it warmer, wind will cool it off. Warm animal bodies of course will be cooled by wind if the ambient temperature is below body temperature, and cooled even more by evaporation. <br><div><br></div><div>Brad</div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Dec 4, 2022 at 7:01 AM Dana Orzel via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</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 class="msg8271198838186705021"><div lang="EN-US" style="overflow-wrap: break-word;"><div class="m_8271198838186705021WordSection1"><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">Dual - Discoverer LI battery bank not sure on battery mode setting (written down but cannot locate at the moment) & no backup generator. Very conservative & minimalist client. I over designed past his energy load evaluation request on purpose as he did not want to have to use a generator. <u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">He has built the entire house off of 2 - small 12 volt PV systems & battery charging cordless tools. Living on site in the garage…<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">I am very impressed with his commitment to low impact & not a wackadoodle or survivalist either. Excellent classical, bluegrass, & jazz cellist.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"><u></u> <u></u></span></p><div style="border-top:none;border-right:none;border-left:none;border-bottom:1.5pt solid windowtext;padding:0in 0in 1pt"><p class="MsoNormal" style="border:none;padding:0in"><span style="font-family:"Century Gothic",sans-serif"><u></u> <u></u></span></p></div><p class="MsoNormal"><b><span style="font-size:12pt;font-family:"Century Gothic",sans-serif">Dana Orzel - E - <a href="mailto:dana@solarwork.com" target="_blank">dana@solarwork.com</a> - C - 208.721.</span></b><b><span style="font-family:"Century Gothic",sans-serif">7003</span></b><span style="font-family:"Century Gothic",sans-serif"> </span><i><span style="color:rgb(153,204,0)"><u></u><u></u></span></i></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"><u></u> <u></u></span></p><div style="border-right:none;border-bottom:none;border-left:none;border-top:1pt solid rgb(225,225,225);padding:3pt 0in 0in"><p class="MsoNormal"><b>From:</b> RE-wrenches <<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>> <b>On Behalf Of </b>Mac Lewis via RE-wrenches<br><b>Sent:</b> Sunday, December 4, 2022 7:41 AM<br><b>To:</b> RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>><br><b>Cc:</b> Mac Lewis <<a href="mailto:maclewis1@gmail.com" target="_blank">maclewis1@gmail.com</a>><br><b>Subject:</b> Re: [RE-wrenches] Sola-ark cold morning<u></u><u></u></p></div><p class="MsoNormal"><u></u> <u></u></p><div><p class="MsoNormal">Hi Dana,<u></u><u></u></p><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">What type of batteries? What battery mode?<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">If you have Lithium batteries with communication enabled, there are certain modes that the BMS is running the charging show. I've seen the Sol-Ark throttle back charge as instructed by the BMS under these circumstances. <u></u><u></u></p></div><div><p class="MsoNormal">A quick check of this would be to start the generator and see if it's on the battery management side or PV only side. <u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">It seems like you are way below the MPPT upper limit if Im looking at the correct QCell spec sheet.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">As far as the temperature theory. You can have temps on surfaces below ambient. This can happen in two ways that I am aware of: radiation and evaporation. The radiation effect occurs because the cold night sky (very cold) is exchanging heat with a surface. This is why you can get ice on lakes above 32F. It's very complex to model this but I doubt you could come close to lowering the temperature far enough to drive the Voc out of the MPP range.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Also, there will be competing heat exchange trying to drive that temperature back to ambient. For example if you had a lot of wind in a clear cold night, the convection heat exchange from the wind would actually warm up the surface.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Evaporation (or any phase change) can drop an object's temperature below ambient as well. It will pull latent thermal energy from objects in order to change the phase of the molecules. This actually has a stabilizing effect on temperature typically because it takes a lot of energy to change phase. This is why people use large water barrels in greenhouses to release latent energy to prevent freezing.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Please let us know what you find out.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Thanks!<u></u><u></u></p></div></div><p class="MsoNormal"><u></u> <u></u></p><div><div><p class="MsoNormal">On Sun, Dec 4, 2022 at 6:22 AM Dana Orzel via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>> wrote:<u></u><u></u></p></div><blockquote style="border-top:none;border-right:none;border-bottom:none;border-left:1pt solid rgb(204,204,204);padding:0in 0in 0in 6pt;margin-left:4.8pt;margin-right:0in"><div><div><div><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">Hey Now All Wise ones!</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">An of gird client emailed yesterday that his Solark had been accepting only 350 watts of a 4KW input from the array. The modules are Q-cell 325 watt 2 strings of 7 modules.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">Sunrise, full sun, no clouds so no edge of cloud effect, negative temps @ -6˚F, he waited all day with no improvement or change in the charge rate consistent 350watts input & then same thing next morning. Negative temps & full sun & 350watts solar input.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">He turned the Solark off for 10 minutes & then turned it back on & 4KW charge input returned. The Solark did not turn off or deliver any alarm or warning.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">My initial thought was over-voltage spike, we designed for a -25˚F scenario & 110 PSF snow load. Beefy! </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">I did not ask if it was windy additionally. Could this contribute to a colder array temp? I have always been of the impression that wind chill did not affect metal or glass that it has to do with moisture being driven off.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">Thoughts & suggestions?</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p><div style="border-top:none;border-right:none;border-left:none;border-bottom:1.5pt solid windowtext;padding:0in 0in 1pt"><p class="MsoNormal"><span style="font-size:14pt;font-family:"Century Gothic",sans-serif"> </span><u></u><u></u></p></div><p class="MsoNormal"><span style="font-family:"Century Gothic",sans-serif;color:rgb(0,32,96)"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:12pt;font-family:"Century Gothic",sans-serif">Dana Orzel Great Solar Works, Inc. </span><u></u><u></u></p><p class="MsoNormal"><b><span style="font-size:14pt;font-family:"Century Gothic",sans-serif">C - 208.721.7003 <a href="mailto:dana@solarwork.com" target="_blank">dana@solarwork.com</a></span></b><u></u><u></u></p><p class="MsoNormal"><span style="font-size:12pt;font-family:"Century Gothic",sans-serif">Idaho Contractor - # 028765 Idaho PV # 028374</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:12pt;font-family:"Century Gothic",sans-serif"><a href="http://www.greatsolarworks.com/" target="_blank">www.greatsolarworks.com</a> <a href="http://www.solarwor.com" target="_blank">www.solarwor.com</a> </span><u></u><u></u></p><p class="MsoNormal"><u><span style="font-size:12pt;font-family:"Century Gothic",sans-serif">"Responsible Technologies for Responsible People since 1988" </span></u><u></u><u></u></p><p class="MsoNormal" style="background:white"><b><span style="font-size:18pt;font-family:Webdings;color:green"> </span></b><u></u><u></u></p><p class="MsoNormal" style="background:white"><b><span style="font-size:18pt;font-family:Webdings;color:green">P</span></b><span style="font-family:Helvetica,sans-serif;color:navy"> </span><span style="font-size:10pt;font-family:Arial,sans-serif;color:green">Please consider the environment before printing this email.</span><u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p></div></div><p class="MsoNormal" style="margin-bottom:12pt">_______________________________________________<br>List sponsored by Redwood Alliance<br><br>Pay optional member dues here: <a href="http://re-wrenches.org" target="_blank">http://re-wrenches.org</a><br><br>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" target="_blank">RE-wrenches@lists.re-wrenches.org</a><br><br>Change listserver email address & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br><br>There are two list archives for searching. 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