One Classic 150 has now switched off because of supposedly too high PV input volts. The PV voltage has always been and still is about 106v as measured, yet is now displaying 169v as per the attachment, on my 48V system and stating it is resting because input volts are too high. Trying to reduce the settings only allows max 5v below that 169V. Switching off the 6 PV circuit breakers makes no difference to that 169V reading.
Help please?
Maybe try a VMM factory reset ?
info on how to do that here https://www.midnitesolar.com/firmwareReport.php?firmware_ID=19&firmwareProduct_ID=1&act=edit
Larry
Hi Frank,
Am not able to look at your attacched .pdf ...
But, the Vin from the PVs is a fairly large variable, depending on temperature, intensity of the Sun, the load that the MPPT Charge Controller places on the PVs, etc.
What is your string configuration, what is the ambient temperature near your PVs??
Here is a Link to the Classic PV String Sizing Tool:
https://midnitesolar.com/sizingTool/index.php
Is this a new system? A 106 V STC String Vmp is often pushing things, unless the lowest, low temperatures for your location, are mild-ish.
Perhaps I am missing something, due to not wanting to download a file to view the attached .pdf .FWIW, Vic
I would suggest reaching out to Jim at Midnite Solar jparish@midnitesolar.com for assistance
Thanks for your replies good people.
Thanks FNG to suggest contact Jim. Will wait for a few more thoughts posted.
Both identical systems are> 6 strings of 3 panels each, about 106V, have been for years, now one Classic 150 displays that 169v input but my M.M. shows 106v on both strings.
Im sure when the input 6 P/V c/b are switched off, after a minute or so the 150 still displays about 60V ??
Vic, The website would only allow me to upload PDF but the descriptions describe it.
Thanks CRAZY for the note on a VMM reset. Sounds scary but may fix it hey.
I realize the Classic150 limit is PV volts plus 48v in my case, but nothing has changed.
Await your helpful comments.
What you are seeing is caused by damage to the PV sense resistors, usually from corrosion from high humidity or salt air environments. Can't be fixed in the field, has to be RMA'd and sent into MNS for repairs and re-calibrations.
Thanks Wizbandit. Still a newby this blog, and just found your reply, sorry.
Oh dear, send to USA to repair? from Oz :( Puzzled about why corrosion? Pretty dry here. I'm a tech and if only knew where to check sense resistor/s first?
Did you see my other post re my other Midnite 150? Replaced the fans (one had seized, one o/c) but there's no 12v. Keeping the temps down with external desk fan for minimal cycling downtime.e.g.15secs Has minimal screen display but gives 50A out on clamp meter and view some readings on laptop app.
Running scared. Think my email notifications work now. :)