Hi All.
I have 18 panels some 310w some 330w. 2 x 250/85 controllers going into a multi plus11 8000. Cerbo GX and Shunt monitoring it all. 6 panels in series, 2 strings going into one controller and 1 string going into another. Used to have Chinese inverter chargers but after a few years it blew up so change to Victron in the hope of something more reliable. Now less than 2 months in one of my solar controllers has blown up. Have sent away just waiting for report back.
I brought off a dealer but have installed myself. He thinks it may have gone over voltage. The 330w panels have an VOC of 41.3. Actually a bit higher than I thougtht as the 310w ones are only 40.3. So worst case 247.8v Open circut so still within the 250 spec.
Looking at the log files max voltage spike since installation has been 233v. Never got to 250v. No warnings or errors on anything since install.
Reading a bit more it seems the 250v is a hard limit. Get to 251 and it explodes. Is that the case? I would have thought if its rated to 250v input it can run up to that ok and there would be some safety margin in their rating. If a tiny spike to 250v blew it up without even a warning or being about to log it would be fairly dissapointed.
Just trying to get as much info as I can before I get an answer on why it blew up. Hopefully just a one off failure and covered under warranty.
Am I just too close to the spec? Should I be dopping down to 5 panels in series to allow more safety margin? 5 just doesnt go into 18 very well. I guess would end up needing a 3rd charge controller to deal with the remaining 3 panels.
Any advice appreciated.
Cheers
I am no expert but for sure 247,8V is too much. There is a victron Excel to calculate the V/A of your strings and shows you if the MPPPT can handle it.
The problem is, that PV Panels are not fixed voltage. The voltage changes with temperature and rises when its colder. Its strange it blows now. Are you from the south?
You could look the 450/100. It has 2 trackers you could do 9x9. I have one with east and west facing arrarys 7 panels per a tracker 390W @ 49.5V. I get really good production.
Yes that sounds a bit close to the max V. The 250V is a very hard limit.
Put your panels in here: https://mppt.victronenergy.com
Yes NZ. Still 15 deg or something when it went so not crazy cold. There is always some load on the system so never see the full VOC anyway.
I did find that calculator but only has victron panels so cant put in the exact details.
Here are screen shots from the logging. At no point it went over 250v. The logging is a bit average only being able to record every min. My last system I could log every sec. When it blew up was floating just under 200. If it did get a little spike it cant have been much. I cant beleive there have zero tollerance and zero protection. No warnings the whole time its been running.
Waiting on the outcome. I would be fairly dissapointed if they dont accept warranty. Sounds like I should be building in more head room and dropping down to 5 panels.
What other areas in Victron do I need to look out for ?
You can fill in your own specs! But as others mentioned, voc voltage is really to close to max, if temp changes you will go over 250v easy
Hi Mark, the VOC of your solar panel may be specified as 41,3 Volt, but there is a tolerance of, usually, 3% and then you’ll end up with 255.23 Volt. Over the maximum of 250 Volt.
And even the measuring tolerance mentioned on the sticker on your solar panels/datasheet of your solar panels may be a bit too conservative.
About the voltage logging. It’s never as good as an actual real measuring instrument, due to the intervals.
If you use the online version you can search a huge database under custom with your panel and it will populate it for you. Also, click the cog on the wodget for details to show actuals and you may see when it exceeded 250V not forgetting VRM logs at best 1m intervals so a spike could be missed.
Thanks everyone for the help. found the advanced tab, Not sure how I missed that.
So it says should only have 5 panels in series.
Still surprised the rated max voltage is a self distruct voltage. And there is not even a few volts tollerance or any warnings. Should be at least getting warnings at a safe level before 250v.
Maybe best is to go 3 in series and have 6 in parrallel. 3 strings into each MPPT controller.
Have to see if I can get the blown one replaced or if they are going to stiff me for a new one. Bit frustrating my Chinese inverter I replaced handled all 18 panels in (6 in series x parrallel) and had 5.5kw out put all for the same cost as 1 MPPT victron controller. Spent 6x more to hopefully get more reliabilty and worse off at the moment…
Cheers