Using PWM and capacitors will help bring it down or to input voltage,
Using a capacitor boost converter (capacitors charged in parallel and load in series) will bring your voltage up to the voltage of all the capacitors added up,
A boost converter using PWM a capacitor and a coil can use 5 components that are cheap and will make easily 200 volts..
To measure the power I would go with a high voltage opto isolator so if the voltage drops say input is 100 volt on the led (highvoltage led) then the output through the photo sensitive device is 4 volt. 100 volt on led 2 volt out, or what ever you want just use ADC on the PIC microcontroller.
Sorry for my bad explanation hope this helps.