The Morningstar SunSaver MPPT Charge Controller enables the use of larger, more economical 60-cell PV modules for 12V or 24V battery charging. With its 15-amp output, it can deliver about 200 Watts into 12-volt battery banks or 400 Watts into a 24-volt battery bank. There's no problem connecting a higher wattage panel - you won't get more than 15 amps, but you will get more energy into your battery. You can still be getting 15 amps even in marginal sun conditions.
Be aware that the input voltage is limited to 75V, which means that charging flooded 24V lead-acid batteries requires a "specialty" solar panel of between 72 and 96 cells. Two 60-cell modules in series is too high an input voltage, but one is not quite high enough voltage for typical recommended 'absorb' voltages. Sealed lead-acid is a different story - 60 cells is enough to meet most manufacturer's recommended voltages. This means that the SS-MPPT-15 most often finds utility in single-panel 12V systems.
The controller has electronic protection from short circuit, overcurrent, reverse polarity, high temperature, high voltage, lightning, and transient surges. An adjustable low battery voltage load disconnect protects the battery from over-discharge. LED indicators indicate charging, low battery, and faults.
The Load circuit helps streamline installation on simple systems. Only 1 overcurrent-protection-device (i.e. fuse) is needed between the controller and battery +, eliminating the need for a second fuse for loads.
The Morningstar SunSaver MPPT Charge Controller automatically detects 12V or 24V battery banks. Be sure your battery has a reasonable voltage before connecting so it self-programs to the proper battery voltage.