In the UK, Octopus offer an electricity tariff where the rate varies every half hour, so you pay more at peak times, and less when there is low demand, particularly if a lot of wind or solar energy is being generated. They also offer an API and various tools so this section is just an exploration of how it can best be used when firing kilns.
Octopus Data Template - Google spreadsheet for energy bought, generated etc
Agile Octopus Dashboard
Octopus APIs documentation
API Access info
Octopus Smart Energy Forum
Guy Lipman's Octopus page and tools