Energy Payback and Life-Cycle CO sub(2) Emissions of the BOS in an Optimized 3.5 MW PV Installation

The energy payback and life-cycle carbon dioxide emissions of the balance of system (BOS) in an optimized 3.5 MW photovoltaic (PV) installation were examined. Tucson Electric Power (TEP) instituted an innovative PV installation program guided by design optimization and cost minimization. The energy payback time (EPT) of the BOS was 0.21 years for the actual location of the plant, and 0.37 years for average US insolation/temperature conditions. The total cost of the BOS components was $940 US per kW sub(p) of installed PV, another milestone in improvement. The results were verified with data from different databases and further tested with sensitivity- and data-uncertainty analyses.