This is a question for your experts out there and I am not one of them. Here is some background and then my question. I have a system that is 24 volts to the batteries and an AIMS 24 volt 6000 watt inverter. I presently have 6 LG panels rated at 330 watts and 2 LG panels rated at 335 watts. Both sets of panels are by LG and have 40.9 volts open circuit (Voc) and have current (ISC) of 10.9 amps and Vmpp of 33.7 volts and Impp of 9.8 amps, model number LG330N1C-G4. My question is: should I wire these panels in 4 groups of 2 panels in series or add a panel and have 3 panels in series in 3 groups (9 panels). How do I maximize panels (wattage) and not exceed the Midnight classic 150 SL charge controller parameters of 150 volts and 96 amps? Regardless of the number of panels, what combination maximizes power to and from the charge controller without adding another controller and obviously not destroy the charge controller? Any help would be appreciated.
Hi Peter, the Midnite string sizing tool is really your best way to determine how many panels and what configurations would work best for you. With the numbers you gave in this post your particular panels the classic would be most efficient working in strings of 2. In this configuration you could use up to 8 panels without exceeding the Classic 150's capacity. I have included an attachment of the string sizing tool with your panels entered(the tool can be found here http://www.midnitesolar.com/sizingTool/displaySizing.php)
Use this : http://www.midnitesolar.com/sizingTool/index.php
As Ms Sunshine posted .
Pay the extra for a real Classic, use the lite & SL for follow me or way more of what your doing. Don't scrimp on the basic start.
VT
VT, He does not need the Classic with ethernet, the SL will do nicely.
If another panel is available then go with the nine panels of 3 parallel strings of 3 in series otherwise the pairs in parallel is ok.
Either setup will not overvoltage the SL. Also it doesn’t matter how many PVs you connect to any Classic, its max output current can only be 96A, you can’t force it to make higher output current
Over panelling is quite common and increases the power production on bad weather days.
Dgd
An added general note on over PV-ing, it's ok on the Classic and often beneficial but generally should be kept under 20% above the charge controllers total rating unless you have extenuating circumstances. So when using the string sizing tool, the "Classics Required" field should not read over 1.2. This is because that power is still being produced although it can't be processed, this translates to heat. Over time excessive heat will cause wear or damage to any electronic device, the Classic is no different.