I had a quick question on floating pins. I know it needs a pull up resistor to prevent the floating, but I'm not sure what value I need. I will be measuring >5V on A0 from a solar panel (approx 3.5V). Because the panel will be at 0 volts at night, or may be disconnected, the pin may float. What value would be appropriate, and will that resistor interfere with a true reading? i.e. it needs to be adjusted for in the calculation.