Written by: Blan Holman, VP, Regulatory Affairs

On September 28, the South Carolina Public Service Commission reaffirmed that the South Carolina Siting Act’s threshold for PSC review of proposed energy facilities applies to an energy facility’s capacity to deliver power to the electric grid, not to the rating of its individual components.  The PSC’s decision is consistent with long-standing Commission practice and precedent, upholds legislative intent, and avoids costly disruptions to the development of solar energy projects in South Carolina.

For background, the 75 MW threshold in the SC Public Service Commission Catalina Solar case refers to the minimum generating capacity of power generating facilities subject to state-level review under the South Carolina Siting Act. The Siting Act was intended to consolidate state regulatory review for large generating facilities, such as coal and natural gas plants. The question in the Catalina case was whether the Siting Act’s 75 MW applicability threshold should be determined based on the theoretical capacity of a facility’s individual components or according to the designed operating capacity of the plant overall to put power on the AC power grid.

AC/DC – What is it? One of the issues raised in the case was whether the Siting Act’s 75 megawatt (MW) threshold refers to AC or DC energy. Alternating current (AC) is what the South Carolina electric system currently uses.  Direct Current (DC) power, by contrast, is produced by solar panels that must be converted to AC before it can be transmitted and used by the grid.  While it is unclear at this point whether the PSC’s decision construes the Siting Act as applying to either AC power, DC power, or both, what we do know is that the Commission’s vote focused on what a power generating plant is designed to produce when operating and serving the grid. That sensible approach declines to focus solely on the DC components of a facility, and instead looks at the plant overall and its designed ability to generate power for the electric system.

Pine Gate Renewables’ position is… Pine Gate agrees with the PSC’s determination that – as has been the practice for 50 years – the Siting Act applies to the designed capacity of a power plant to deliver energy to the electrical system.  The Siting Act is a statute meant to consolidate state review of large generating plants and their role on the South Carolina grid. Notably, if a large plant receives Siting Act approval, the ability of local governments to review a facility is reduced. The PSC’s decision prevents the Siting Act from being applied too broadly, which could hinder affordable clean energy development in South Carolina but also diminish local control.