Year-round experimental 4E assessment of an integrated PV/T-BIPV system in an nZEB-oriented test building

This study presents a 12-month field assessment of a 3.55 kWp hybrid solar-envelope system comprising a 1.10 kWp rooftop water-based photovoltaic/thermal (PV/T) subsystem and 2.45 kWp of semi-transparent building-integrated photovoltaic (BIPV) modules installed on the east, south, and west façades of a single-room test building in Elazığ, Türkiye. Annual AC-side renewable electricity generation was 4,327.30 kWh, whereas the adopted annual electrical-load scenario was 3,033.50 kWh. These values correspond to an annual generation-to-load ratio of 142.65% and a nominal generation-minus-load balance of + 1,293.80 kWh. Monthly aggregate generation exceeded the adopted monthly load from February through November. However, these monthly balances do not establish continuous electrical self-sufficiency, self-consumption, or gross grid exchange. The PV/T GHI-referenced thermal-energy index reached a maximum of 55.90%. The area-weighted GHI-referenced system energy and exergy indices ranged from 12.74 to 25.21% and from 8.73 to 14.56%, respectively. These quantities are reference performance indices rather than plane-of-array conversion efficiencies because orientation-specific irradiance was not measured. The embodied energy was 18,018 kWh, and the reported exergy-referenced energy-payback indicator was 3.18 years. Under the load-limited and full-generation electricity-crediting boundaries, the conditional gross carbon-inclusive simple payback periods were 12.57 and 8.81 years, respectively. Combined ± 20% electricity-price and carbon-price scenarios produced simple-payback values ranging from 7.34 to 11.01 years. Under the fixed-factor, full-generation grid-displacement boundary, the estimated operational grid-emission displacement was 2,812.76 kg CO 2 /year, corresponding to 142.08 kg CO 2 /m 2 /year; at the assumed carbon price, its conditional monetized value was 219.40 USD/year. The results provide a boundary-aware year-round benchmark for PV/T-BIPV integration in nZEB-oriented test buildings under continental climatic conditions.