Benefit-Cost Study of Distributed Generation Leaves Questions Unanswered

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In April, the cost-benefit analysis of distributed generation (i.e. rooftop solar) initiated by House Bill 219 was submitted by NorthWestern Energy to the Public Service Commission. The report is now public and is required to be included in the next electric rate case, which is expected to begin in September.

Staff at MREA have reviewed the study. First, no work papers, data spreadsheets, or any other supporting materials were included with the report. This makes it incredibly difficult to verify the report’s claims. This lack of transparency is concerning, especially considering the ultimate goal of this report was to bring clarity to questions on rooftop solar, not create further confusion or suspicion. Without the ability to verify the claims made in the study, they cannot be taken as fact.

Second, even without verification the study has a number of questionable and unexplained elements in it that need further clarification. There are several critical assumptions in the report that, if calculated inappropriately, could significantly alter and/or bias results. Without key pieces of the underlying data, inputs, and assumptions used in the report it remains very challenging to conduct a detailed analysis to verify the report’s methodologies and claims. Until these types of verifications can be made, it’s hard to avoid being skeptical. We will remain engaged with this study as more develops.