Direct Coupling Solar PV Gains Easy Access

The California Energy Commission’s Rule 21 Working Group determined that grid connected solar PV systems installed using the “direct coupling” approach offered by Nextek Technology does not require a utility interconnect agreement.

Nextek is the only solar photovoltaic (PV) company that offers a solar electric system for grid-connected locations that doesn’t require the use of inverters. This recent ruling will help pave the way for more installations in California. The Rule 21 Working Group develops the interconnection requirements for distributed generation. It is made up of representatives from California utilities, regulatory agencies, and industry. California’s standards are used as a model by many other states. After analyzing the architecture this system, they recognized that “direct coupled” commercial PV systems from Nextek do not require the reviews and approvals needed for all other grid-tied inverter-based systems. Before Nextek, all grid-connected photovoltaic solar systems required an inverter. These inverters, converting the locally generated electricity to grid-compatible AC power, use energy themselves, need a utility interconnect agreement, and are required to shut down in the event of grid failure. While the solar modules are the most expensive part of a solar electric project, the inverters also contribute a certain cost to the system. Doing without inverters, Nextek argues, helps drive the cost of the project down. Nextek achieves this by identifying and powering DC loads inside commercial buildings. Fluorescent lighting ballasts are replaced by high-efficiency DC ballasts and powered by the PV solar system at greater efficiencies than when the power is converted by an inverter. In addition to lighting, Nextek can power variable speed motor drives, DC computer power supplies, and other loads. “This increases efficiency, enables the lights to stay on in a power failure, and eliminates the need for a utility interconnect agreement,” the company said. Power for this system can come from solar panels, wind turbines, fuel cells, batteries, or any DC power generation equipment. The Nextek technology uses the locally generated power first, then uses grid power only when needed. The Nextek approach to PV systems can be seen in commercial establishments around the country including Target Stores, Whole Foods Markets, Inc., PowerLight corporate offices, an IBEW training center, the architectural firm of William McDonough + Partners, and more.

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