I want to measure the Mains voltage (230V/50Hz) using an ADC channel from a microcontroller.

This is my current approach ... 

Below I have two schematics that add two voltages (one direct, one alternating). 

Added to that, the both the AC and DC signals are going through voltage divider, but that isn't important. 

I'm guessing that the output voltage on the second schematic is lower because of the impedance of the capacitor?

[![Schematics][1]][1]


  [1]: https://i.sstatic.net/eevPY.jpg