It's nice to see an extra line on the graphs with the expected electricity generation for that day/month/year.
The expected amount of electricity generation for solar panels can be calculated for europe on the site of the EU:
http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php#:
So it should be possible to fill out the expected kWh per month for a solar sensor to be able to show this info...