Effect of glass Na content on adhesional strength of PV modules

Effect of reduction of soda-ash content and more effective fixing of sodium in superstrate sodalime glass surface on durability of PV modules was studied. Damp-heat acceleration-tested PV modules having higher soda-ash content glass or normal SO₂-treated glass were most severely stained. Their adhesional strength was the lowest and delamination was most severe. High concentrations of impurities correlated with regions of delamination. Increasing the intensity of SO₂ treatment reduced the surface roughness, degree of staining, powder formation, and delamination; and increased the adhesional strength. The best approach is to reduce the sodium content as well as to fix the remaining sodium by an adequate sulfur-dioxide treatment and having fixed it not to disturb it during subsequent processes.