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Your page about controllers, MPPT Solar Charge Controllers Explained — Clean Energy Reviews has a section about Solar Panel Voltage vs Battery Voltage. Here is an excerpt:
… For an MPPT charge controller to work correctly, the solar panel operating voltage must be at least 4V to 5V higher than the battery charging (absorption) voltage, not the nominal battery voltage. On average, the real-world panel operating voltage is around 3V lower than the optimum panel voltage (Vmp).
I believe this is only true fur PWM controllers. For example, Renogy states that their MPPT controllers can raise the solar input voltage to the voltage needed for battery charging, so-called boost controllers.
I hope this helps,
jon stivers acimasolar.com