The power monitor will not give accurate readings when used with a meter that receives supplemental power from solar panels.
Solar panels contributing power cause the disk in the meter to spin backwards to account for the amount of power that your panels are contributing to your energy usage. The Power monitor can not tell if the disk is rotating backward or forward, and it will only show how much power is going through the meter (either being consumed or generated by your house). Therefore the meter will read both the forward and backward spins as power usage and incorrectly calculate the incoming power as power consumption.
If the solar panels that are hooked up downstream of the meter (between the house and the meter), then the Power Monitor will not be able to measure the total power consumption of the house, since it can not measure the contribution from the panels.