Holistic assessment of co-located solar photovoltaics and greenery in the tropics: Results on solar photovoltaic output, greenery growth, and roof surface temperature

Co-located solar photovoltaics and green roof systems have gained increased attention for generating renewable energy and incorporating greenery in urban environments. However, few studies approach the topic from a holistic approach of such a system in tropical climates. In this study, the impact of co-located solar photovoltaics and greenery in a tropical climate was investigated across three functional benefits: 1) solar photovoltaic output, 2) greenery growth, and 3) roof and ceiling surface temperature. Results revealed 1) an increase in photovoltaic performance ratio with greenery [absolute increase of 1.0 ± 0.8 %], 2) shade-tolerant plant species located under photovoltaic modules exhibited a significantly higher horizontal ground coverage with good health and vigour [absolute increase of 19.8 ± 8.0 %], and 3) lower roof surface temperature under co-located solar photovoltaics and greenery [reduction of 4.7 ± 0.1 °C]. To quantify the multi-functional impact of the co-located system, the Roof Equivalent Ratio is proposed, which was adapted from the Land Equivalent Ratio used in agrivoltaics, to which a roof equivalent ratio of 2.39 was obtained for the study. The results of this study could inspire similar research, especially in the tropics, to incorporate renewable energy generation through solar photovoltaic and greenery for sustainable urban environments.