NOVELTY - A tandem photovoltaic cell device (200) comprises: a lower cell (230) configured for substantial independent operation of an upper cell (220); an upper cell coupled to the lower cell; a first edge sealing material; and a second edge sealing material.    USE - The tandem photovoltaic cell device is useful for converting solar energy into electrical energy.    ADVANTAGE - The tandem photovoltaic cell device is highly reliable, efficient, and environment friendly.    DETAILED DESCRIPTION - A tandem photovoltaic cell device (200) comprises: a lower cell configured for substantial independent operation of an upper cell, the lower cell comprising: a lower glass substrate material (219); a lower electrode layer (217) made of a reflective material overlying the glass material; a lower absorber layer (215) overlying the lower electrode layer, the absorber layer made of a first semiconductor material having a first band gap energy (Eg) in a range of 0.7-1.1 eV; a lower window layer overlying the lower absorber layer; a lower transparent conductive oxide layer overlying the lower window layer; a first optical coupling material comprising first ethylene vinyl acetate overlying the lower transparent conductive oxide layer; the upper cell coupled to the lower cell, the upper cell comprising: an intermediary glass substrate material, the intermediary glass substrate material comprising a thickness, a lower surface, and an upper surface, the thickness being about 1.1 millimeter and less, the lower surface being overlying the optical coupling material; a first upper transparent conductor layer overlying the upper surface of the intermediary glass substrate material; an upper p type absorber layer overlying the first upper transparent conductor layer, the p type conductor layer made of a second semiconductor material having a second band gap energy (Eg) in a range of 1.5-1.9 eV; an upper n type window layer overlying the upper p type absorber layer; a second upper transparent conductive oxide layer overlying the upper n type window layer; a second optical coupling material comprising first ethylene vinyl acetate overlying the second upper transparent conductive oxide layer; and an upper glass material overlying the upper transparent conductive oxide layer; a first edge sealing material provided between the lower glass substrate material and the lower surface of the intermediary glass substrate material; and a second edge sealing material provided between the upper glass material and the upper surface of the intermediary glass substrate material.    DESCRIPTION OF DRAWING(S) - The drawing shows a simplified diagram of a cross-sectional view of a multi-junction photovoltaic cell.    Photovoltaic cell device (200)    Cover glass (201)    TCO (203, 211)    Window (205, 213)    Upper absorber layer (207)    Electrode (209)    Lower absorber layer (215)    Lower electrode layer (217)    Lower glass substrate material (219)    Upper cell (220)    Lower cell (230)    Intermediary glass substrate material (231)