Tag Archives: rate design

Commentary on CPUC Rate Design Workshop


The California Public Utilities Commission (CPUC) held a two-day workshop on rate design principles for commercial and industrial customers. To the the extent possible, rates are designed in California to reflect the temporal changes in underlying costs–the “marginal costs” of power production and delivery.

Professor Severin Borenstein’s opening presentation doesn’t discuss a very important aspect of marginal costs that we have too long ignored in rate making. That’s the issue of “putty/clay” differences. This is an issue of temporal consistency in marginal cost calculation. The “putty” costs are those short term costs of operating the existing infrastructure. The “clay” costs are those of adding infrastructure which are longer term costs. Sometimes the operational costs can be substitutes for infrastructure. However we are now adding infrastructure (clay) in renewables have have negligible operating (putty) costs. The issue we now face is how to transition from focusing on putty to clay costs as the appropriate marginal cost signals.

Carl Linvill from the Regulatory Assistance Project (RAP) made a contrasting presentation that incorporated those differences in temporal perspectives for marginal costs.

Another issue raised by Doug Ledbetter of Opterra is that customers require certainty as well as expected returns to invest in energy-saving projects. We can have certainty for customers if the utilities vintage/grandfather rates and/or structures at the time they make the investment. Then rates / structures for other customers can vary and reflect the benefits that were created by those customers making investments.

Jamie Fine of EDF emphasized that rate design needs to focus on what is actionable by customers more so than on a best reflection of underlying costs. As an intervenor group representative, we are constantly having this discussion with utilities. Often when we make a suggestion about easing customer acceptance, they say “we didn’t think of that,” but then just move along with their original plan. The rise of DERs and CCAs are in part a response to that tone-deaf approach by the incumbent utilities.


Three key steps in designing rates for solar power

KQED posted a good summary of how solar power is driving the residential rate design rulemaking at the CPUC. (M.Cubed works for EDF there.) I offer three steps that should be taken to address the issues of how to change ratemaking for a changing energy marketplace:

1) Consumers should see time varying prices (time of use or TOU being among that menu). Tiered rates make it impossible to see the current price for consumption, and tiered rates have been shown not to induce any additional conservation across the customer base. Consumer surveys show that customers want more control over their electricity use and the price signals to direct them.

2) Consumers should be offered a meaningful menu of rate options. This means rates that differ in risk exposure both over time of day and time horizon. Customers should be able to hedge against peak day prices or participate in demand response. They should be able to accept changes in hourly prices or buy a multi-year contract. Utilities already offer these contract options to their suppliers; why not treat their customers as they they are valued?

3) Any calculation of grid costs and responsibility should reflect the changing demand by consumers. The grid charges proposed by the utilities assume that future consumers will install the same-sized equipment as they do today and that they will consume in the same pattern. Solar panels are ready today to “island” a home from the network, and EV charging could create greater load diversity even at the circuit level. That will radically change utility investment. The distribution planning rulemaking is an important step toward resolving that issue but the CPUC hasn’t yet linked the proceedings.

Only the first issue is being addressed head on in the rulemaking and it hasn’t really delved into the importance of emerging consumer choice.