I am working on a DC voltmeter for monitoring my solar panels. Total voltage of my panels can go up to a maximum of 50 volts. I designed a voltage divider with 100k and 10k resistors. For full voltage it gives 4.54 volts on arduino pin.
The problem that I am confronting is that the behaviour of the voltage is not linear. It gives perfect value for one input voltage but changes drastically for other input voltages. I have seen some pages on instructables that suggest that I am neglecting the something related to impedance issues of arduino pins but I could not get it. My simulation on proteus works perfectly but in practical design I could not got to any point. Kindly help me regarding high impedance voltage reading on arduino pins.