I just got my first bill since going to a community choice power provider. Here in California, the investor owned utilities (commercial companies, not the publicly-owned utilities) act as retailers of energy. They buy power on the open market from generators, then sell it to their customers. They bill both for the cost to generate the power, and also for power delivery (which includes maintaining the grid). An option that recently became available is for a city government to join a community choice power provider, which then buys power from generators on our behalf. The utility still delivers it, so it’s not real competition, but partway there. The community choice provider then bills the utility, who passes that bill along to individual customers.
So, the generation cost went down by about 30% for power used during the day, and a few percent for power delivered at night (three different time-of-use categories). Our community choice provider has an option for 100% renewable power, which I chose, so this is a pretty tangible demonstration that renewable power really is cheaper than fossil fuels.
Utilities are publicly owned for a good reason. Your bill would otherwise shoot up sky high the very moment your provider became a monopoly, and utilities are natural monopolies.
Many of our collective bills would go down if we pushed for more public ownership of natural monopolies and let go of the failed conservative dogma that beneficial competition is what happens when there are no rules. Comcast is what happens when there are no rules and natural monopolies are allowed to be privatized.