a multilayer conformal coating is optimized in both composition and geometry to protect the back and sides of a transparent - fronted thin - film solar photovoltaic panel or similar device from various damage mechanisms associated with long - term outdoor exposure without an additional backcap or edge frame . a “ barrier stack ” or “ barrier layer ” of inorganic moisture - barrier and chemical - barrier layers is applied to the back of the photovoltaic functional film stack , extending into a bare - substrate border zone around the functional stack edges . the barrier stack shields the functional stack from moisture and chemical invasion , and the coated border zone effectively seals the vulnerable edges of the functional stack . an “ envelope stack ” or “ envelope layer ” of thicker polymer films is applied over the mechanically delicate inorganic barrier stack and around the solar photovoltaic panel edges . the envelope stack electrically insulates the solar photovoltaic panel and substantially protects the panel back and sides from mechanical shock , stress , and abrasion , thermal stress , fire , weathering , and uv - exposure degradation .