Lightweight and Scalable Hierarchically Engineered Epoxy–Graphite Composite Coatings for Passive Thermal Management of Photovoltaic Modules

Photovoltaic (PV) technology is central to global decarbonization efforts, however, PV deployment in hot and humid climates, such as those prevalent in ASEAN countries, is severely constrained by elevated operating temperatures that can exceed ∼60 °C, leading to accelerated degradation and reduced energy conversion efficiency. Although numerous thermal management strategies have been explored, many rely on active cooling or complex system integration, introducing penalties in cost, weight, and scalability. Here, we report a lightweight and scalable passive cooling strategy based on a thermally conductive epoxy coating that can be directly applied to the rear surface of PV modules. The epoxy matrix is engineered with bulk graphite (GC) and graphitic carbon quantum dots (GCQD) to enhance heat dissipation through the backsheet. Coatings were fabricated using a doctor-blade process with GC loadings ranging from 10 to 70 parts per hundred resin (phr) to systematically evaluate structure–property–performance relationships. An optimized composite formulation incorporating GC (50 phr) and a small fraction of GCQD (4 phr) exhibits markedly enhanced thermal transport, resulting in a surface temperature reduction of 2–3 °C under outdoor operating conditions. This temperature suppression translates to a relative efficiency gain of up to ∼9% at ∼48 °C while maintaining a low coating density of 1.43 g cm–3. The combination of low cost, minimal added weight, and scalable processing makes this epoxy-based coating a practical passive thermal management solution for large-area PV installations in high-temperature environments, with potential benefits for module reliability and lifetime extension.