Hi, iv got 2 different small solar panels that reach 19 volt each in sun. My charge controllwe is 24volt so i wanna wire them in series but when wires in series, the open voltage shows about 42 volt but when connected to charge controller it drops to about 19 volts. does this sound about right ? thanks martin
You obvious do not have an MPPT charge controller ,so the panels will drop to the level of your battery bank, which is clearly not in good shape if it is 19V.
what i want to know is, if the open circuit voltage is 42ish volts, then when connected to a charge controller with no load or batteries should it still read 42v on the charge controller or does the charge controller rob a few volts? Am i right in saying MMPT charge controllers are really expensive still ? thanks
It all depends on your particular charge controller, but most will not do anything until a battery is connected, and even the cheap ones can auto-sense a 12V or 24V battery bank. MPPT controllers are more expensive but they generally yield 30% or more watts to the battery as they operate at the optimum solar panel voltage regardless of what the battery voltage is.
