"D-E-C" rates contain a demand charge, energy charge and a customer charge.   Hours-Use rates, often called block rates, have more than one energy charge that varies according to the customers hours-use or load factor.  A declining block rate has energy charges which decrease as hours-use increases.  An inclining block rate has energy charges which increase as hours-use increases.  Hours-Use rates may or may not also contain demand and customer charges.

Time-of-day and seasonal rates contain separate charges applicable to the customer's usage measured during defined periods.  The demand charge and/or the energy charge may be time differentiated or vary by season.      

Interruptible and curtailable rates provide discounts for the customer agreeing to reduce load upon notice.  Some interruptible rates may allow customers to buy-through during certain conditions, requiring the customer to reduce load only during critical periods (i.e. system emergencies).  Curtailable rates usually allow customers to curtail on a voluntary basis, however, usage consumed during curtailment periods is priced at a higher rate.

Real-time pricing rates contain charges that vary.  Prices may be provided by the utility to the customer via the internet, fax, telephone, or pager, and may be provided a day ahead or a week ahead or under another basis.  Some real-time pricing rates apply to the total usage while other real-time pricing rates are designed to apply only to incremental usage (deviations from baseline).   Real-time prices may be based on costs or may be market based.    

For the same service, one rate schedule, when applied to a particular customer's usage, may produce an amount that is higher or lower than another rate.  A combination of factors determine which rate will be the most favorable rate.  These factors include, but are not limited to, the customer's maximum demand level, load factor, power factor, and seasonal and time-of day variations in load.