I have a classic 150 that is one of two controllers for my off-grid system.
My batteries are in a 24v config.
Panels are set up in pairs, delivering ~76v (vmp x 2) to the controllers in strings
I have approx 5kw on the roof.
I have just lost one controller (internal board failure), not the midnite. My question is can the mdnite handle more strings? If so, how many more?
Also, what is this called as I tried searching on overdrive, overclock...?
Thanks in advance.
Overpanel
If you have full sun, I can see a problem with 100% overload
If it's cloudy and you are nowhere near full output, should be no problem.
Issue happens when the sun pops out and power goes way up before the controller can throttle back, maybe a Midnight tech can state what happens, when that happens.
If you severely over-panel a Classic, or most MPPT controllers, it will current limit but it does this by raising the PV input voltage.
Running the controller at full output current at higher input voltage makes the controller run hotter is all.
Yes, it might also take a bit longer to current limit. Have to take each situation individually.
boB
So if I were to set the classic to limit current to, say, 80 amps, what effect would that have on my situation?
Thanks for the replies
dogfox,
Personally, would use the Classic String Sizer, and FOLLOW the recommendations that result:
http://midnitesolar.com/sizingTool/displaySizing.php
It is not clear what was the cause of the board failure, but significantly over PVing MPPT Charge Controllers (CCs) will add stress to them.
Your location may be subject to thunderstorms and lightning. Using Surge Protective devices is strongly recommended on the PV inputs, and inverter outputs (at a minimum).
Also, will add, that each CC must have its own separate PV array, am certain that you know this ...
FWIW, Vic