As indicated on this Hydro Ottawa page the price of electricity depends on the hour you’re using it, and the rate periods are different in summer and winter. The mid-peak/on-peak times are reversed in summer and winter. Here are the respective times for Summer Weekdays (May 1^st to Oct 31^st); Winter Weekdays (Nov 1^st to April 30^th); and Weekends and Holidays:

      

Prices effective November 1, 2016:

  Off-Peak: 8.7 cents / kWh
  Mid-Peak: 13.2 cents / kWh
  On-Peak: 18.0 cents / kWh

For real-time rates go here.

You can also save electricity by buying more energy efficient bulbs and appliances. Click on the image below to enlarge this chart showing the relative efficiency of different types of light bulb.

You can also cut costs by minimizing phantom power—i.e. energy consumed by appliances and electronics are plugged in, but turned off.