The impact of different substrates on solar module performance

A research team has analyzed the effects of different substrates on PV module performance and has found that ground soil achieves the highest efficiency at 21.1%, followed by grass (19.6%), wood (17.95%), concrete (16.2%), roof tiles (14.3%), and iron sheets (11.5%).

Researchers from Uganda's Kampala International University have tested the effect of different substrates on the performance of monocrystalline solar panels and have found that substrates with lower thermal conductivity and higher albedo, like ground soil and grass, help the modules achieve higher efficiencies.

Their analysis considered panel temperatures and power outputs daily for half a year, with measurements being taken every hour between 6 am and 6 pm and averaged per hour to represent the entire half-year period.

“The albedo effect influences temperature and can have significant implications for solar panel efficiency and thermal management,” explained the team. “Albedo refers to the measure of the reflectivity of a surface or material. It is the ratio of reflected solar energy to the total incoming solar radiation. Surfaces with a high albedo, like snow or white roofs, reflect more sunlight and absorb less heat, making them cooler. Conversely, surfaces with low albedo, such as asphalt or dark soil, absorb more sunlight, contributing to higher temperatures.”

Six types of mounting surfaces were analyzed: concrete, iron sheet, wood, grass, ground soil, and roof tiles. PV panels with a maximum power output of 70 W were placed on different surfaces with a tilt 0°. Temperature sensors measured each surface's upper and lower areas and the panels' back and front temperatures.

“Iron sheet had the highest temperature of 79 C followed by roof tiles at 70 C, then concrete at 58.8 C, then wood at 50.5 C, then grass at 41.2 C while ground soil had the lowest temperature of 42.3 C,” the scientists said. “The results were further taken for correlation analysis. Iron sheet correlated 0.954, meaning that a rise in surface temperature leads to a 95.4% rise in the cell temperature. For roof tile, it was 0.973; for concrete, it was 0.964; for wood, 0.88; for grass, 0.954; while for ground soil, it was 0.846.”

Per the results, the efficiency of the material was seen to reduce as cell temperature increased, with the lowest efficiency achieved at mid-day when the temperature was highest. The highest efficiency was in ground soil at 21.1%, grass at 19.6%, wood at 17.95%, concrete at 16.2%, roof tile at 14.3%, and iron sheet at 11.5%.

“Natural substrates like grass and ground soil were found to maintain lower panel temperatures, improving the efficiency and longevity of monocrystalline solar panels compared to artificial substrates like iron sheets and roof tiles,” the team concluded. “The study confirms that lower panel temperatures are critical for enhancing performance. Transpiration in natural substrates plays a significant role in heat dissipation, keeping panels cooler and improving efficiency during peak sunlight hours.”

The results were presented in “Effects of substrates on the efficiency of a monocrystalline solar panel,” published in Scientific Reports.