Mark, what you are describing is almost a daily occurrence in Florida in the summer. It can start raining buckets in full sun. And the rainwater is much colder than what comes out of a hose here.
There does not seem to be any real data out there - only conjecture and anecdotes. I understand why manufacturers might put that into a manual out of an abundance of caution, but I have never seen any real testing. Jason Szumlanski Principal Solar Designer | Florida Solar Design Group NABCEP Certified Solar Professional (PVIP) Florida State Certified Solar Contractor CVC56956 On Mon, Oct 23, 2023 at 1:22 PM Mark Downing via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > Indeed, spraying cold water on hot modules between the hours of 10A-2P (or > maybe 9A and 3P) is simply foolish. > Now the argument of rain being more dangerous than a cold hose is pretty > weak. > If it's raining, the modules are simply not going to be hot! > It would only be an issue if conditions went from full sun to raining > streetcars and busses within the time period of a couple of minutes. > ------------------------------ > *From:* RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> on behalf > of White, Will via RE-wrenches <re-wrenches@lists.re-wrenches.org> > *Sent:* Monday, October 23, 2023 9:44 AM > *To:* RE-wrenches <re-wrenches@lists.re-wrenches.org> > *Cc:* White, Will <will.wh...@fluke.com> > *Subject:* Re: [RE-wrenches] Cleaning PV mods > > > I worked with a guy who had done installs in Arizona. He had an off-grid > customer spray down their array with cold well water in the middle of the > day, which shattered the module glass. > > > > I’m sure it was an isolated incident, but it happened. > > > > Thanks, > > Will > > > > *From:* RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> *On > Behalf Of *Jason Szumlanski via RE-wrenches > *Sent:* Friday, October 20, 2023 4:47 PM > *To:* RE-wrenches <re-wrenches@lists.re-wrenches.org> > *Cc:* Jason Szumlanski <ja...@floridasolardesigngroup.com> > *Subject:* [EXTERNAL] Re: [RE-wrenches] Cleaning PV mods > > > > *CAUTION:* This email originated from outside of the organization. Do not > click links or open attachments unless you recognize the sender and know > the content is safe. > > > > I don't understand the thermal shock nonsense. It routinely starts > downpouring here when it's blazing hot out (sun showers) and the rain is > way cooler than ground water in summer. It makes no sense. If hose water > from the ground is going to hurt solar panels, you better not put them > where it rains! > > > > I replied privately to Dana, but for the benefit of the group, it takes a > heavy soiling to make any appreciable difference. I have done numerous > tests at times of high pollen and found little to no benefit to cleaning > solar panels. Certainly it would not be worth paying someone to do it. > Other climates may have different results. My suggestion would be to test > first. Module level power electronics can provide incontrovertible proof. > > > > Jason > > > > > > On Fri, Oct 20, 2023, 4:21 PM Dave Tedeyan via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > > Hi Dana, > > > > See attached from REC. I would imagine these guidelines would apply to all > modules. > > Cheers, > > Dave > > > > On Fri, Oct 20, 2023 at 3:56 PM Dana Orzel via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > > Hey ally ‘all, > > > > Ok bad solar installer! 7 years & I have never cleaned my modules & live > on a dirt road. Yeah rain does a good job with the dust but there is a film > mostly on the edges. > > > > What does everyone do for cleaning? > > > > My array is 16’+ tall on a hill side. I have a pressure washer & was going > to pick up a large sponge type mop & mount it on a painters extension pole. > > > > Good Biodegradable cleaning solutions? > > > > > > _________________________________________________________ > > Dana Orzel GREAT SOLAR WORKS! > > C – 208.721.7003 E – d...@solarwork.com > > W - www. greatsolarworks.com > <https://urldefense.com/v3/__http:/greatsolarworks.com__;!!KPww_GFiJXw!Y_kuM7c-s1IyVKAFmwI_3s4QdWIAuH3dA6C9UrdDyGVPbrAubqjhW4VUC0zvVmJ3YqDCwomVHcoSXnJViwOe2rxR3PsYzpCS$> > www.solarwork.com > <https://urldefense.com/v3/__http:/www.solarwork.com/__;!!KPww_GFiJXw!Y_kuM7c-s1IyVKAFmwI_3s4QdWIAuH3dA6C9UrdDyGVPbrAubqjhW4VUC0zvVmJ3YqDCwomVHcoSXnJViwOe2rxR3PW0Drer$> > > *“Responsible Technologies for Responsible People since 1988!”* > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > <https://urldefense.com/v3/__http:/re-wrenches.org__;!!KPww_GFiJXw!Y_kuM7c-s1IyVKAFmwI_3s4QdWIAuH3dA6C9UrdDyGVPbrAubqjhW4VUC0zvVmJ3YqDCwomVHcoSXnJViwOe2rxR3CxvfLvy$> > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <https://urldefense.com/v3/__http:/lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org__;!!KPww_GFiJXw!Y_kuM7c-s1IyVKAFmwI_3s4QdWIAuH3dA6C9UrdDyGVPbrAubqjhW4VUC0zvVmJ3YqDCwomVHcoSXnJViwOe2rxR3Evi2PJX$> > > There are two list archives for searching. 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