Installed our solar panels and charge controller today, but the charge controller is getting no power from panels. Tested the leads coming from solar panels and they are testing at 21 volts. Our charge controller is a Renogy 20amp mppt charge controller. We happen to have 2 of these and neither one is getting power. Customer support verified everything hooked up right, but what are the odds that two controllers are bad? Are we missing something in the set up?