Measuring light intensity with solar cell

How connect a small solar cell with a max voltage of 3.6V.
I try something but there is a problem with.
If i connect to a analog pin and ground i get the voltage from the solar cell but it is not the same
as the voltage measured with a voltage meter.
I found that there is already a voltage between the analog pins and the ground from the arduino board with nothing connected on.
This voltage as influence the voltage of the solar cell.
Someone any idea how to resolve this problem.

Many thanks

Louis

I found that there is already a voltage between the analog pins and the ground from the arduino board with nothing connected on.

True. That is called a "floating input" and is to be avoided.

No measurement is exact.

Just as two clocks usually disagree, two voltmeters will not give the same reading.

How small is the solar cell. If >1mA, add a 4k7 resistor between solar+ and analog input. That stops the cell phantom powering the Arduino through the input protection diodes when the Arduino happens to be off. A load resistor across the solar cell fixes the floating input problem. Value depends on the size of the solar cell. Try 100k. Leo..

Leo,

Thanks for the respons. Now i have a stable output voltage.

Louis