Have created a little automation in Node-RED to switch the utility Meter select tariff in the Utility Meter integration to allow the collection of energy data into seperate tariffs at the correct time . As a bounus it also create a sensor which poulates with the correct price , which can be added to the energy dashboard. This have been setup for Octopus Go , but the tarff times and rates can be changed to what ever is required. You can add as many inject nodes as required.
Documentation is in the flow. I have scubbed my home assistant instance using scubber from node-red-contrib-home-assistant-websocket. you may have to add your home assistant id back into the home assistant nodes 
[{"id":"e73d6a5ae7ac9caa","type":"tab","label":"Electric","disabled":false,"info":"","env":[]},{"id":"f3a5f57f72444f53","type":"api-call-service","z":"e73d6a5ae7ac9caa","name":"Rate Name","server":"","version":5,"debugenabled":false,"domain":"select","service":"select_option","areaId":[],"deviceId":[],"entityId":["select.electric_monthly"],"data":"{\"option\":payload}","dataType":"jsonata","mergeContext":"","mustacheAltTags":false,"outputProperties":[],"queue":"none","x":370,"y":260,"wires":[["256e5387f6b6ff4b"]],"info":"Change tariff to match triggered rate supported by the utility meter."},{"id":"cc787d00065f71e1","type":"inject","z":"e73d6a5ae7ac9caa","name":"Off-peak Electric","props":[{"p":"payload"},{"p":"rate","v":"0.05","vt":"num"}],"repeat":"","crontab":"30 00 * * *","once":false,"onceDelay":0.1,"topic":"","payload":"Off_Peak","payloadType":"str","x":150,"y":220,"wires":[["f3a5f57f72444f53"]],"info":" * msg.payload = tariff name\n * msg.rate = tariff rate"},{"id":"faeaae79adeb4558","type":"inject","z":"e73d6a5ae7ac9caa","name":"Peak Electric ","props":[{"p":"payload"},{"p":"rate","v":"0.1564","vt":"num"}],"repeat":"","crontab":"31 04 * * *","once":false,"onceDelay":0.1,"topic":"","payload":"Peak","payloadType":"str","x":140,"y":300,"wires":[["f3a5f57f72444f53"]],"info":" * msg.payload = tariff name\n * msg.rate = tariff rate"},{"id":"256e5387f6b6ff4b","type":"ha-entity","z":"e73d6a5ae7ac9caa","name":"Rate","server":"","version":2,"debugenabled":false,"outputs":1,"entityType":"sensor","config":[{"property":"name","value":"electric_rate"},{"property":"device_class","value":"monetary"},{"property":"icon","value":""},{"property":"unit_of_measurement","value":"£/kWh"},{"property":"state_class","value":""},{"property":"last_reset","value":""}],"state":"rate","stateType":"msg","attributes":[],"resend":true,"outputLocation":"payload","outputLocationType":"none","inputOverride":"allow","outputOnStateChange":false,"outputPayload":"","outputPayloadType":"str","x":510,"y":260,"wires":[[]],"info":"Create new sensor for Energy management dashboard"},{"id":"020cde0d99f6cc1e","type":"comment","z":"e73d6a5ae7ac9caa","name":"Info (click me)","info":"This flow will provide the automation for the\nUtility Meter integration\n\nhttps://www.home-assistant.io/integrations/utility_meter/\n\nIt wilso create the sensor required for tracking costs on the energy dashboard\n\nhttps://www.home-assistant.io/docs/energy/electricity-grid/\n\nParameters required :-\n\n\nConfigure (copy) inject nodes to match start times for each energy tariff\n\nChange the msg.payload in the inject node to match tariff name for Utility Meter integration \n\nchange msg.rate in the inject node to match the tariff rate for the energy dashboard\n\nChange the entity name in the rate name node to match the Utility Meter integration tariff name\n\nThe rate node will create and update the following sensor for use in the energy dashboard\n\nsensor.electric_rate ","x":210,"y":80,"wires":[]}]