The Ins and Outs of Electricity Rate Design

Electricity rate design has the power to completely alter the energy sector, for better or worse. The world of electricity rate design can be a confusing one, so before we get into which rate design would be most beneficial for you and the energy sector (that’s for a later blog post!), let us first define and explore three of the main types of rate designs.

Fixed Charges and Consumption Charges – The current system for billing electricity for most utilities across the country, this rate design charges fixed fees in tandem with a usage bill and is most common with residential consumers. Fixed charges never change from month to month (as the name implies), as they are there as a result of your connection to the grid. Recently, utility companies across the country have been advocating for significant fixed charge increases. In theory, a fixed charge is there to compensate the utility for the fixed portion of their costs as a result of having you as a customer (for instance, the cost to bill you and read your meter).

Time of Use – This system is decidedly more complicated than the previous one, and would require some work on the part of you, the consumer. The idea is simple: the cost of using electricity would change according to the time of day (for instance, customers would be charged higher rates for using electricity during specified peak demand times).

Figure 1: An example of a suggested TOU rate for summer months. Source:

The execution of Time of Use (TOU) rates (such as advocacy and ensuring customer understanding) is where the system becomes more complicated. States such as California and Massachusetts have already adopted a TOU rate design, and our own Tennessee Valley Authority has also proposed making the transition to TOU rates. Additionally, TOU rates are already available in most states on a voluntary basis. At its most basic, TOU rates provide price signals to customers to encourage them to use when rates are low and conserve when rates are high.

Peak Demand Charges – In many states and especially for commercial customers, electricity use is billed in two ways by the utility: based on consumption, that is, how much electricity you actually used in a given period, and peak demand, or the highest capacity required during that billing period. A simple way to think about this is with an analogy: the odometer in your car would represent the “consumption,” and the fastest speed you traveled during that period would be the “peak demand.” Your car needs to be able to last for a long time (high mileage) but also may need to go fast from time to time (of course, if you drive a Tesla Model S, that’s all the time! But we digress…). In the case of this electricity rate design, you would be charged for both consumption and peak demand, and oftentimes these two charges appear as one combined charge.

The main idea behind peak demand charges is that they provide customers with price signals to encourage them not to make large, instantaneous demands on the systems but instead to spread their usage out over the day more smoothly. Depending on the rate structure in a given area, and your habits, demand charges can constitute up to 30% of an electricity bill.

A future blog post will lay out the pros and cons of each of these rate designs, so stay tuned!

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