- A Cumulative Imbalance for a noncore customer is the difference between actual usage (plus adjustments and carryovers) and actual deliveries (plus shrinkage)
- A Cumulative Imbalance for a Core Procurement Group* is the difference between actual calendar month gas deliveries and the sum of each day's "modified determined usage" for that same calendar month. The modified determined usage is:
- a day-after the gas day usage estimated by Pacific Gas and Electric Company (determined usage)
- plus the amount of the Operating Imbalance Carryover Account (generally 1/12 of the Carryover Account balance) applied to the month's supply.
- plus any accounting adjustments, divided by the number of days within the month
- Cumulative Imbalances may be traded:
- with other Cumulative Imbalances from the same calendar month, and/or
- into or out of storage
- with tradeable Operating Imbalances
- The imbalance tolerance band is 5% of metered or determined usage
- Cumulative Imbalance statements will be sent during the month after the delivery month
- Imbalance trading occurs during the second half of the month after the delivery month
- Customers can trade Cumulative Imbalances past zero, subject to a 3% limit
- Each Cumulative Imbalance trade must meet one of the following criteria:
- the trade moves the imbalance towards zero
- the trade results in an ending imbalance within +/- 3% of metered or determined usage
- Any remaining Cumulative Imbalance within the tolerance band will be carried forward to the following month's Cumulative Imbalance
- Any Cumulative Imbalance in excess of the tolerance band will be cashed out as described in Cashout Components in the month after imbalance trading
- The Cumulative Imbalance Cycle gives more details regarding date ranges for these different phases in the process
Managing Cumulative Imbalances
Noncore customers have three options for managing Cumulative Imbalances: manage their own imbalances, authorize a nominating market to trade imbalances or assign imbalances to a balancing agent. See Managing Cumulative Imbalances for further details.
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Core Procurement Groups include Pacific Gas and Electric Company's Core Procurement Department and Core Transport Groups as defined in Schedule C-GT.
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