Utility Rate Switch Modeling Capabilities

I work with Jacob Lynch and want to elaborate a little on his comment. Our goal is to properly account for the economic value of distributed PV generation. With respect to utility electric bill savings we calculate the value by subtracting the expected utility bill that the ratepayer will pay after the solar system has been installed from the expected utility bill that they ratepayer will pay if they do not install solar. This incorporates the change in net consumption as measured by the utility meter as well as any expected changes in the utility rate tariff. We assume that if a ratepayer meets the qualifying criteria for multiple rate tariffs that they will opt for the tariff that results in the lowest bill for their particular consumption profile. Often this means that our customers will change to a time-of-use rate when we interconnect their solar system.

Currently the energy value figure calculated in SAM assumes that the ratepayer doesn't change their rate tariff. If they were eligible for a better tariff prior to installing their solar system then the calculated figure overstates the savings. What we would like to see would be, in addition to the energy value, a calculation of the resultant utility bill. Then we could run two variations: one with PV and a PV friendly rate, another without PV and with the initial rate. By comparing the resultant bills we could determine the total savings. Note that we'd also need to be able to run a simulation with no generation (system size of zero). Currently I believe the minimum system size is 500W. Another option would be to allow us to input two different rates (a before and an after) into a single simulation.

Thank you for considering this request. I'd like to add that we're deeply impressed by all the work that has been put into SAM over the years. It's truly a robust and comprehensive tool that provides immeasurable value to our industry.

Kind Regards,

William Yeager

SAM 2014.1.14 comes with a SamUL script that calculates an energy value based on a comparison of one rate structure for the renewable energy system, and another for the grid-only option.
See Comparing different rates  for details.
Best regards,

Paul.