Preparation method and key parameters of a novel gel foam for photovoltaic fire suppression

Photovoltaic (PV) fire accidents caused by arc faults and hotspot effects pose growing safety risks globally. Conventional Class A foam fails in PV fire scenarios owing to poor adhesion on smooth inclined glass surfaces and wind dispersion susceptibility, leaving modules vulnerable to sustained heat exposure and thermal-stress-induced fractures. In this study, we develop a novel gel foam (NGF) with superior adhesion, wind resistance, and thermal protection performance specifically tailored for PV fire suppression.

The NGF was formulated from sodium dodecyl sulfate (SDS), konjac glucomannan (KGM), and sodium sulfate (Na₂SO₄). A three-factor, three-level orthogonal experiment was used to optimize their concentrations using the expansion ratio (E), the drainage half-life (T_1/2), and a composite foam comprehensive index (FCI) as evaluation metrics, yielding three candidate formulations. Foam retention was assessed on a 45° inclined glass platform at wind speeds of 0, 6, and 25 m/s. Thermal insulation performance was quantified under a far-infrared radiation system at 15 kW/m², with thermocouples at the foam surface and at 10 and 20 mm depths; total heat absorption was calculated via radiative heat transfer modeling. Finally, two sets of full-scale thermal protection experiments were performed using a 35 cm-diameter gasoline pool fire beneath a standard-size PV module (1640 mm × 990 mm), with visible and infrared cameras recording surface damage and temperature distribution in real time.

Among the three factors, KGM concentration had the greatest influence on E and T_1/2, followed by Na₂SO₄ and SDS concentrations. Increasing KGM and Na₂SO₄ concentrations enhanced solution viscosity and promoted three-dimensional gel network formation through hydrogen bonding and polar interactions, thereby increasing T_1/2 while decreasing E. The optimal formulation (0.5 wt% SDS, 0.8 wt% KGM, and 1.0 mol/L Na₂SO₄) achieved the highest FCI of 3528.7, with E = 5.2 and T_1/2 = 904.8 min. In retention tests on a 45° inclined glass surface, this formulation maintained retention rates of 82.04%, 80.39%, and 82.13% at wind speeds of 0, 6, and 25 m/s, respectively. Meanwhile, conventional Class A foam retained only 15.27% at 0 m/s and collapsed entirely at 6 and 25 m/s. These results demonstrate that NGF provides considerably more stable surface adhesion under static and high-wind conditions. In thermal insulation experiments, compared with conventional Class A foam, the foam collapse time of the optimal formulation was extended by 243.2% and total heat absorption capacity increased by 250.5%. In full-scale fire tests, NGF-coated PV modules exhibited substantially more uniform surface temperature distributions than uncoated modules. During early combustion, the foam absorbed heat through liquid drainage, stabilizing module temperature; as burning continued, the foam drained downward and hardened. Post-experiment inspection confirmed that NGF-protected modules sustained substantially less physical damage.

The developed NGF, leveraging the synergistic salting-out gelation between KGM and Na₂SO₄, forms a robust three-dimensional network that delivers superior adhesion, wind resistance, and thermal stability on inclined smooth PV glass surfaces. Compared with conventional Class A foam, the optimal formulation offers markedly higher retention under wind exposure, a 243.2% longer thermal insulation duration, and a 250.5% improvement in heat absorption capacity. Full-scale fire experiments validate its effectiveness in suppressing temperature rise and preventing thermally induced module fracture under realistic fire conditions. This study provides a scientific foundation and technical reference for developing next-generation fire suppression and thermal protection materials tailored to PV fire scenarios.