Demand charge

A demand charge is a utility bill cost set by the highest power (kW) a customer draws over a short interval, not by the total energy used. One source describes the interval as just 15 minutes per month. Demand charges are a large and growing share of commercial bills. One source says they now make up more than 50% of a typical commercial bill, and that commercial demand charges in California have risen by 100% in the last decade. Traditional energy efficiency measures do not help a site avoid demand charges, because the charge follows short peaks in power draw. Energy storage can cut demand charges. Storage controller settings such as Stem Athena utility bill optimization can be set to reduce demand charges only, or demand and energy charges together. One storage qualification guide flags a site as a good fit when demand charges are more than 20 dollars per kW per month, or when they are more than 50% of the bill. Utilities adjust demand charges together with time-of-use energy rates and demand response programs, because energy costs more at certain times of day.

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• sentence 1: support check: partial - u12 says demand charges are costs calculated by the maximum power (kW) used in just 15 minutes per month. It does not say they are not set by total energy used, and it does not describe a general short interval.
• sentence 3: support check: partial - u12 says traditional efficiency measures won't help avoid demand charges. It does not give the stated reason that the charge follows short peaks, although the 15-minute maximum-kW basis implies it.
• sentence 4: support check: partial - u23 shows settings for demand charges only and for demand plus energy charges. It does not state in general that energy storage can cut demand charges, although the settings imply it. -->