The Virginia State Corporation Commission has approved the continued use of a grid security device that could make midsize solar projects financially exorbitant.
In early February, the state’s SCC authorized the utility Dominion Energy to continue making demands direct transfer journey (DTT) for interconnected solar and storage projects, which prevent distributed energy sources from generating power when operating independently of the grid, or ‘islanding’, when not necessary.
Producing isolated power in this way can pose safety risks, such as keeping power lines energized during a power outage. But critics of DTT believe that existing utility and inverter safety protocols can limit these risks.
DTTs apply to interconnected solar projects of 250 kW or higher. The Interstate Renewable Energy Council (IREC) believes that the cost of implementing DTTs could prevent solar and storage projects from happening at all. IREC reported in a study published in July that DTT communications components, such as radios or fiber optic wiring, can cost tens to hundreds of thousands of dollars, and solar project developers to purchase them.
“This is an incredibly disappointing result after years of collaboration between industry and utilities, decades of research and gigawatts of interconnections in other areas that all prove DTT is indiscriminate for use in inverter DER applications,” said Brian Lydic, chief regulatory engineer for IREC.
In that report, IREC estimates that an “unintended island scenario” that could pose safety risks is unlikely – that it would happen “once every approximately 3,800 to 10,000 years.”
“These claims are supported by empirical data, as there has only been one documented sustained island event in North America, which occurred under highly unusual transmission-level conditions not addressed by typical DTT schemes,” the report said.
As Virginia hobbles its community and commercial solar markets by requiring DTTs, other states in the region are installing this scale of solar at a faster pace.
“It is disappointing that – at a time of historic energy price increases, in the data center capital of the world – Virginians will have less access to the energy cost savings of community DERs,” said Shay Banton, regulatory program engineer and energy justice leader at IREC.
