In a deregulated wholesale electricity market environment, where generators are thought to compete to provide the cheapest energy, the question arises on how to request monopolistic distribution wire companies to also make their contribution to efficiency. Benchmarking regulatory models have developed that aim at requesting those companies to perform efficiently, both in investment as well as in operation. "Model" companies that provide the distribution service are being used as a regulatory tool in countries worldwide. Starting from the real company, a model is built redesigning the high and low voltage distribution systems. Tariffs are finally designed based on the model. The experience is revised and practical problems discussed. Frontiers of efficiency concepts are being proposed by researchers to overcome present limitations of the regulatory models.

In a deregulated wholesale electricity market environment, where generators are thought to compete, the transmission network is the path to make true that competition. However, the transmission system is a monopolistic activity that needs to be regulated. Not only adequate transmission tariffs and their allocation have to contribute to generation competition, but also adequate transmission expansion. A revision is made of transmission regulation and how different countries have solved the expansion dilemma, from central State planning to open market approaches. Cooperative game theory has been a subject of intensive research as a solution to the issue of transmission financing and, most recently, transmission expansion.