The Arduino Micro has four analog inputs. We use one to make a voltmeter, and add an I2C display.
To select and use a solar panel efficiently you need to know more about it than the manufacturer will tell you. Here is how you find that information.
The Arduino reads the voltage output from an LM35 temperature sensor, calculates the temperature, and displays the result on an LCD.
Arduino makes a great camera controller. It can be used to prevent vibration, or as an intervalometer.