Optionally use UTC as basis for units tariff rate time changes

I would like to have an option for users to be able to have the times of day when ‘units’ tariff’s charging rates change be based on UTC, rather than summer time/ local wall-clock value. This if provided should be the user’s choice. If the user chooses that their bands’ timings be based on UTC, then the times should be as currently used when summer time is NOT in effect ie time zone UTC+00. The reason is greater ease of implementation of software that depends on this.