Multi-objective optimization based PV-battery storage system sizing with judicious excess energy transfer framework fostering net-zero energy buildings

Adopting net-zero energy buildings (NZEBs) is a key global strategy for attaining international climatic goals. Integrating onsite renewables is vital for NZEBs, and solar photovoltaic (PV) is widely adopted for its geographical flexibility. However, it demands a battery energy storage system (BESS) or grid support to tackle its natural intermittency, which invokes an affordability-reliability trade-off. Therefore, multi-objective grey wolf optimization (MOGWO) with net-zero focus has been employed in this study to optimally size the PV-BESS for different buildings with levelized cost of energy (LCOE), loss of power supply probability (LPSP), and excess energy index (EEI) as minimization objectives. Despite attaining a competitive compromise solution, EEI and LPSP often become inevitable. To address this issue, an excess energy transfer framework between the DC buses is facilitated and analyzed. The benefits achieved from the proposed framework motivated the optimal sizing of an energy-intensive building while utilizing excess energy transfer from neighboring buildings. This collaborative energy transfer approach cuts BESS requirements by 41 %, lowers LCOE by 37 %, reduces LPSP by 8 %, and eases grid burden by 6 % annually for the considered building compared to the scenario without excess energy transfer. Further, attempting simultaneous optimal sizing of all considered buildings ensures net-zero attainment, while providing similar cost and energy benefits. Hence, incorporating excess energy transfer from the planning stage enables urban high-rise buildings, even with limited rooftop space for PV installation, to become NZEBs economically, thus fostering sustainable power generation across urban environments.