Designing a Photovoltaic Array for Smith College
The development of distributed solar energy is an opportunity for individuals and institutions to support the growth of the clean energy economy, lower their carbon footprint, promote energy security, and potentially save money. This thesis created a decision-making framework for photovoltaic (PV) solar development that focused on the interplay between technical design, stakeholder needs, and constraints. First, stakeholder needs and constraints were assessed and translated into design criteria. Next, eligible sites for solar development were identified and their on-site loads were quantified. Preliminary system layouts were designed for the chosen sites. Capacity and energy production for these arrays was estimated using software modeling and verified with transposition calculations. Optimal combinations of grid connection and financing structure were identified after analyzing regulatory, operational and financial constraints. Finally, design criteria were applied to the arrays and used to determine recommendations for development.
This framework was applied to Smith College as a case study and was based on commercially available technologies and policies in the present and near future. Since Massachusetts is expected to transition to a new solar incentive program next year, both short-term and long-term recommendations were made. A 16 kWAC roof-mounted array on Conway House, the smallest system considered, was recommended for development within the next year. For the long-term, community-shared solar canopies on the parking garage (183 kWAC) and the tennis court parking lots (156 kWAC) were recommended after analyzing feasibility and social, environmental and financial impact, including a life-cycle cost assessment. If both arrays were developed, community-shared solar participants would collectively lower their electricity bills by up to $168,000 per year and pay the developers $111,000 per year for installation, operation and maintenance of the system, for combined savings up to $57,000 per year. Through a sensitivity analysis, it was determined that the lifetime benefits were most sensitive to capital costs and also sensitive to the clearing price of competitive procurement, which has not yet been established. In general, large PV arrays (≥25 kW) connected behind Smith’s main meter were not recommended for development because the variability of solar energy would interfere with the smooth operation of the cogeneration plant.