Time zones, daylight saving & rate periods

An instant and a clock label are different

The timestamps 2026-11-01T01:00:00-07:00 and 2026-11-01T01:00:00-08:00 refer to different instants, one hour apart. A file containing both can be correct. A duplicate check that only compares “1 a.m.” would wrongly delete real consumption.

During the spring change, the local clock skips an hour. That gap in clock labels is not a gap in a continuous sequence of offset-aware instants.

Use the utility’s rules, including its holidays

SMUD and Portland General Electric use Pacific local time, but that does not make their holiday calendars interchangeable. A federal observed holiday does not necessarily make electricity off-peak.

SMUD’s fixed-date holidays use the actual calendar date in this snapshot. Its July 4 holiday in 2026 does not turn Friday July 3 into an off-peak weekday. Always inspect the specific rate calendar.

A reading can cross a price boundary

An hour-long interval from 4:30 to 5:30 p.m. crosses a 5 p.m. rate boundary. Without finer measurements, the file cannot reveal how much energy belongs to each rate.

Exact mode refuses that allocation. An explicitly selected proportional mode can split by elapsed time, but the result is estimated and may differ from the actual load pattern.

Meter configuration can matter

PGE documents special timing behavior for certain non-network meters. This release requires a confirmed supported network meter for its Time of Day calculation. A wall-clock assumption is not a substitute for knowing the meter configuration.