An interconnection standard includes the technical requirements and the legal procedures whereby a customer-sited generator interfaces with the electricity grid. Generally, the distribution utility must study and approve a proposed DG system within a framework established by the state’s public utilities commission. Utilities traditionally have determined which systems may connect to the grid and under what circumstances. This arrangement presents a conflict of interest that can result in significant barriers to customer-sited DG. For example, a utility might apply a complicated set of procedures—better suited to a 1,000 MW nuclear power plant—to a 2-kW residential photovoltaic (PV) system, or impose steep fees, redundant safety requirements and other obstacles.
While the underlying engineering standards and requirements are well-known (generally, the IEEE 1547 standard covers all the bases), an engineering standard is not a complete procedure. A complete interconnection procedure must address fees, timelines, insurance requirements and indemnification, forms and certain other issues to provide a comprehensive procedure that supports investment in customer-sited DG—either by individuals or by project development investors.
Wherever the standard is unclear, or where redundant or unnecessary tests or steps are piled on the existing national standards, the results can be costly, significantly affecting small generators. To ensure best practices and eliminate the potential for utility interference, the interconnection process must be governed by a transparent, non-arbitrary set of provisions.
Consider the invoice shown here. Assume Ray McSolar purchases a 2-kW system—more expensive per watt than a larger solar installation, but enough for his needs. His state’s interconnection rules force him to install a redundant external disconnect switch, allow his electric utility to charge him extensive fees, and require his system to endure significant testing— all of which add nearly 10% to his system cost and are unnecessary.
With $48.50 in average monthly savings from the electricity Ray’s PV system generates, it will take him more than two years to pay off the red tape involved with the installation of his system.
