Five steps from a problem to its solution.

Help me design and build a first working prototype for this problem in Australia.

Problem: Households in Australia can't easily tell which electricity plan is cheapest for the way they actually use power.
Who it hurts: Households who have stayed on the same plan for years or on the default offer, including people with solar or changing usage.
The moment it hurts: A quarterly bill after a price rise, with a line saying they could save by switching but no clear answer on which plan fits them.
What people do today: People ignore the savings line, call their retailer, or try comparison sites that ask for usage they don't know.
Why it is still unsolved: Plans differ by tariff type, time of use and discounts, so the cheapest plan depends on a household's own meter data, which most people never see in a usable form.
What solved looks like: A household uploads a bill or connects their smart meter data, and gets a ranked list of current plans priced on their real half-hourly use over the last year, with the yearly saving and the steps to switch.
Where: Australia

First, list what you would need to learn from the people affected before building, as interview questions.
Then propose the simplest version that would help, the screens or messages it needs, and the data it would use.
Keep it cheap to run, accessible, and respectful of people's privacy. Flag anything you are unsure about instead of guessing.