Techno-Economic Analysis of a PV-Battery System for a Commercial Building Under Different Utility Rate Structures

The synergy between solar photovoltaic (PV) systems and behind-the-meter battery storage to reduce utility costs in buildings has drawn increasing attention. This paper presents results of a case study involving an economic analysis of battery-supported PV systems for an existing two-story commercial building in Albuquerque, New Mexico under different utility rate tariffs. The building, with 17,430 ft² conditioned area, has been modeled in a detailed building energy simulation program, and hourly building electricity demand data and electricity demand generated using Typical Meteorological Year 2 (TMY2) weather file. The effect of strategies leading to demand leveling and demand limiting have also been discussed. Parametric analysis using System Advisor Model (SAM) software has been performed to determine the optimal sizing of the PV and battery systems for the given electric demand profiles under the assumed utility rate tariffs which will result in largest net present value (NPV). The results have been found to be highly sensitive to the costs of the PV systems and battery packs. Under the assumed realistic circumstances, we find that the inclusion of a battery pack in either a new or existing PV system does not improve the NPV even when the cost of battery storage is reduced from its current $250/kWh down to an unrealistic $50/kWh.