Power consumption is pretty straightforward. When something(like your tv) says it uses 210 watts, that 210 watts per hour.
So, you simply multiply the hourly consumption by the number of hours it's left on.
If you watch 12 hours of tv per week:
210 watts * 12 hours = 2520 watt hours, or 2.52 kWh.
Or, you can just look at your bill from the power company to figure out how much you use.
Then try
this site because solar panel power generation is not quite so simple.