Study finds greenery can grow under solar panels

Findings challenge view that they cannot be in same space as both need direct sunlight

- Chin Hui Shan

A new study in Singapore has found that co-locating solar panels and green roofs not only uses space more efficiently and enhances rooftop greenery, but also boosts electricity generation and cools buildings.

The higher energy output and lower indoor temperatures could, in turn, help building owners cut costs.

The study was done by the Building and Construction Authority (BCA), National Parks Board (NParks) and National University of Singapore (NUS).

The findings challenge the traditional view that solar panels and green roofs are mutually exclusive as both systems need direct sunlight, said researchers of the study.

"The conventional understanding is that if greenery is shaded by solar panels, the greenery will not thrive due to reduced photosynthesis. However, in this study, we were able to have greenery grow beneath solar panels," said Associate Professor Stephen Tay, who is the lead researcher.

Prof Tay, who is from the department of the built environment at the College of Design and Engineering at NUS, said that the main motivation of the study is to assess if co-location of solar panels and greenery is feasible for Singapore, which faces land constraints.

Four different set-ups were tested on the rooftop of Alexandra Primary School in Bukit Merah for a year from November 2021 to October 2022.

The set-ups were: a bare concrete roof, a bare green roof, a concrete roof with solar panels, and a green roof with solar panels.

Measurements included the electricity generation of solar panels and roof surface temperatures.