Regulators play an important role in stabilizing the cost of electricity (in terms of the tariffs paid by consumers of electrical energy).
Firstly, where the regulators are working in the right way, they help avoid the formation of cartels in the energy sector: those being cartels that can manipulate and eventually wreck havoc on electricity tariffs.
Secondly, where the regulators are working in the right way, they help in the fight against monopolies in the energy sector: keeping in mind the fact that monopolies tend to be inefficient, resulting in high costs.
Thirdly, where the regulators are working in the right way, they tend to ensure that all players in the energy sector play by the rules, which ensures that no players have undue advantage over others. The end beneficiaries of all this are the end users of electricity.
These matters are explored further in energy economics books. You can buy such books (in e-book format) from places like Barnes and Noble and Amazon. Before being able to shop on such sites, you will probably need to sign up. And to sign up with the sites, you may need to, say, create Gmail account at www.gmail.com – as an email address generally has to be supplied during the sign ups.