Floating Solar: A Blue Alternative to Green Energy

In 2015, the Borough of Sayreville, NJ and J&J Solar Power, LLC began the collaboration for the construction and operation of a Floating Solar Array at the Borough’s Water Treatment Plant (WTP). The team included RETTEW as the design engineer whose scope included full permitting and design. The purpose of the array was to reduce both the annual electricity costs at the Borough’s Bordentown Avenue WTP and increase sustainability by reducing carbon emissions. Benefits to a floating array also included a reduction in the amount of environmental disturbance on the site, a significant reduction in potential tree removal, and reserving the adjacent land for expansion or other future needs. In addition, a floating array stays cooler, increasing output efficiency, and reducing evaporation from the water surface. Floating solar is popular internationally but, it was, and is, a mostly new concept in North America. RETTEW worked closely with regulatory agencies to not only permit the array but to define the permitting process for future floating solar systems. The 4.4MW(DC) array is installed on a floating ballast system, manufactured by Ciel et Terre (CeT), specifically designed for waterborne solar installations. Each section is interlocked with the adjacent sections to create a single mat that can withstand wind and other environmental factors. The total array covers approximately 10.2 acres. Power is transferred from the array to the shoreline at a single location on the eastern side of the array to meet the centralized inverter/transformer pairs and combined to connect to the interconnection point. The floating array produces the annual electrical requirements of the WTP, qualifying for Net Metering under NJ regulations. Power produced by the floating array is fed directly into the WTP’s electrical systems, displacing grid-based energy resulting in an immediate reduction in the usage and load. However, during favorable periods, the array generates more power than the WTP’s needs. Through a bi-directional meter installed during the interconnection process, this excess power is credited against the Borough’s electric account charges up to the annual generation amount. In effect, the Electrical Generation Costs and Electrical Distribution Costs are displaced by the Power Purchase Price under the PPA. These projects have shown to be viable in NJ because of the health of the Solar Renewable Energy Credit Market in the State. These credits allow developers to finance the full design and installation of the project, provide reduced power costs to the client and still make a profit. This presentation aims to introduce the technology to conference goers, share the benefits of floating solar and walk through the challenges and ultimate solutions that arose during the design and construction of the nation’s current largest floating solar array.