Model (At Least) Twice, Build Once: Experiences With the Design-Bid-Build Process for Solar Photovoltaic Arrays

Commercial-scale solar photovoltaic (PV) arrays were designed, constructed, and are now operational on the Gaithersburg, Maryland campus of the National Institute of Standards and Technology (NIST). A design-bid-build process was followed where the contractors used photovoltaic system modeling tools both during the initial design phase and during the postbid, prebuild phase. To help investigate the specific aspects of the contractors' evolving designs, the authors conducted their own independent photovoltaic system modeling. This independent modeling helped identify design elements that could be improved and so aided efforts to maximize the annual renewable energy generation. An estimated 2.5% gain in annual energy generation is being realized as a result of this independent modeling effort. To provide context for the modeling work and the lessons learned, key events impacting the design-bid-build process are described. The installed systems are summarized and also contrasted with the proposed designs. The power generation at three sites are compared over two different 12-month intervals.