Variable rate plans are always month-to-month, save for three-month intro specials in which your rate stays the same for those early months. Fixed rate plans, on the other hand, are available for periods ranging from six to 36 months. The contract lengths, and how that length influences the price per kWh rate, varies enormously from company to company. Some companies offer lower rates when you enroll for longer periods. Others raise the rate slightly. The competing rationale: You will be paying them for longer so you get a break, or you have that price locked in when energy rates inevitably rise. One rule of thumb — the longer the contract, the higher the cancellation fee.
Another unwelcome side effect of not knowing your average monthly kWh usage level is that you may end up paying more than you expect. This can occur when a customer inadvertently shops an electric rate based on a higher usage level than they actually use. Electricity suppliers commonly advertise their electric rates associated with the highest (2000 kWh) usage levels since those tend to be the lowest rates.
Although electricity had been known to be produced as a result of the chemical reactions that take place in an electrolytic cell since Alessandro Volta developed the voltaic pile in 1800, its production by this means was, and still is, expensive. In 1831, Michael Faraday devised a machine that generated electricity from rotary motion, but it took almost 50 years for the technology to reach a commercially viable stage. In 1878, in the United States, Thomas Edison developed and sold a commercially viable replacement for gas lighting and heating using locally generated and distributed direct current electricity.