Context <p>Driven by the carbon neutrality goals, photovoltaic systems have been widely deployed in northwestern China and become a prominent landscape feature. Understanding the thermal effect of photovoltaic is crucial for offering key insights into the energy balance processes and dynamics of this emerging landscape.</p> Objectives <p>We quantified the impact of photovoltaic systems landscapes on its surrounding area and addressed three key questions: (1) Do photovoltaic systems landscape produce a warming or cooling effect? (2) What are the patterns and driving factors of the thermal effect? (3) Is there an optimal patch size for maximizing thermal impacts in bare land landscape?</p> Methods <p>We utilized Landsat-8 imagery, combined with field observation data, to explore the thermal effects of 86 photovoltaic sites in northwestern China, incorporating the accumulative thermal indicators and threshold value of efficiency for all seasons in 2019.</p> Results <p>Photovoltaic systems showed a steady cooling effect throughout the year. It produced cooling effect of 166.23 hectares with a temperature difference of 1.58&#xa0;°C. The average thermal intensity was 0.05 and thermal gradient was 0.44&#xa0;°C. Only thermal intensity exhibited seasonal variations. The area was the dominant factor for the maximum thermal indices, while temperature inside the station and albedo significantly influence the accumulative effect. The threshold value of efficiency determined the optimal landscape size to be 127.47 hectares.</p> Conclusions <p>This study confirmed that photovoltaic systems consistently exhibited a cooling effect on the surrounding LST and provided crucial evidence for determining the optimal landscape size. It provided an important reference for assessing the scale and impact of future photovoltaic landscape.</p>