Every solar facility in Dominion Energy Virginia’s expanding fleet of silicone panels is failing to perform up to its initial energy promises, according to a State Corporation Commission staff analysis. In many cases the shortfalls are dramatic.

A high confidence in the ability of solar power to replace Virginia’s dominant natural gas and coal electricity generators is at the heart of the Virginia Clean Economy Act, still a key plank in the Virginia Democrats’ 2025 campaign platform. This latest cold splash of reality is just one more sign that it takes closed eyes and blind faith to continue to trust that path forward. 

The performance data popped up in testimony that is part of the utility’s application for a base rate increase. There are dozens of issues in that pending case, set for a public hearing September 2. They range from the allowed profit margin to a new rate structure for the giant data centers. But one side issue is whether the company has earned a bonus on its profit margin due to good performance, and the SCC staff have recommended it not get it, in part because of the poor solar performance.

Neil Joshipura of the SCC staff wrote in his testimony:

Based on the data provided, all of the Company’s solar facilities had average actual capacity factors that were lower than their respective design capacity factors. The absolute differences between the design and actual values ranged from 1.2 to 10.3 percentage points, with an average difference of 4.3 percentage points. Piney Creek Solar had the largest absolute difference; its design capacity factor was 22.6 percent, while its actual capacity factor for 2024, the only year with available data, was 12.3 percent. This represents a 48 percent shortfall relative to the design value.

Capacity factor is a measure of how often a power plant produces electricity, and it is never 100% peak production 100% of the time. When the plant is advertised as producing 100 megawatts (MW) or 500 megawatts or more, that is the energy output at peak production. That must then be multiplied by the capacity factor, the actual output divided by the maximum possible energy output.

In the case of these utility-owned solar fields here in Virginia, that capacity factor is a very low number, usually about or below 25% in design capacity and about 20-21% in actual output. That is the average output after all the nighttime hours, all the days with little or no direct sun, and all the days down for maintenance are accounted for. Hurricane Erin, for example, has brought Virginia several low solar days due to clouds.

Joshipura’s testimony included a table that listed the “capacity factor” for 25 Dominion solar plants for 2023 and 2024, the performance period being reviewed in the rate case. It then compared that to the amount of production the utility projected when the facilities were designed and installed. The nominal discrepancy was more than four percentage points, but that is misleading. Many produced 20% less electricity over those years than what we ratepayers were promised.

Steve Haner is a Senior Fellow for Environment and Energy Policy. A previous version of this article appeared in Bacon’s Rebellion. Steve Haner can be reached at Steve@thomasjeffersoninst.org.