Generally, the generation of electricity is unrelated to anything on your bill. Power plant companies generate electricity and sell it to utilities as well as retail electricity providers in deregulated areas. The electricity is then resold to you, the customer. Transmission and distribution is taken care of and charged to you by your utility, regardless of what company supplies the electricity. These charges are separate from the supply portion of your bill.
The more cool air you lose, the harder your air conditioning unit works and the higher your electricity bill will be. Install blinds, hang curtains or get storm windows made to keep cool air from seeping out. Even mesh screens, on the outside of your home, will help deflect solar radiation. You might even consider replacing old windows that leak cold air and let in heat.
Switching electricity supplier could shave pounds off your bills. But it’s not always about how much hard cash you could save. You might be fed up with poor customer service, you might want greater visibility of your usage through an app or you might want to choose your supplier based on their green credentials, or whether they supply a smart meter.