The Federal Energy Regulatory Commission of the USA in mid-September passed a rule to allow small energy resources such as rooftop solar and electric vehicle batteries to supply electricity to the wholesale grid, as the Financial Times reports. Although state regulation in respect to retail electricity prices is also expected to be influential, the new rule may be quite significant for utilities, as it is estimated that by 2025, there may be as much as 380 GW of such “distributed energy resources” (by comparison, there is currently around 1100 GW of generation capacity active in the US). For electric vehicle batteries, the idea is that they might charge at times of high solar PV electricity production and relatively low power consumption (mid-afternoon, for instance), when spot prices tend to be low, and then be able to release electricity to the grid at times when demand is higher. This could reduce the frequency of the need for peaking power generation capacity, making it less economic to deploy. Whether the addition of distributed energy resources will lead to a well-balanced grid is uncertain, though on the surface it appears that it could.