Metallization of crystalline silicon solar cells for shingled photovoltaic module application

Abstract The shingled photovoltaic (PV) module is a high-power PV module technology that is manufactured cells dividing and bonding with an electrically conductive adhesive (ECA). Here, the ECA is composed of 70–80% of silver, an acrylic, and a solvent. We focused on the formation of solar cell metallization suitable for the shingled PV module. Generally, the Ag pads on the rear side of the crystalline Si solar cells don’t printed on the Al surface because of the peeling problem. Therefore, a back surface field (BSF) layer is not formed at this area. The characteristics of the solar cell can be improved by applying a rear Ag pad together with the BSF layer in the entire area of the back surface of the solar cell. The formation of the Al-BSF layer and the peeling of the Ag pad off from the interface between Al-BSF and Al were analyzed using by a scanning electron microscope. The peeling phenomenon could be removed by the adjustment of the elevation rate to the peak temperature during co-firing process. The external quantum efficiency (EQE) analysis revealed the influence of the full Al-BSF layer on the rear side of the solar cells showing higher values in the long-wavelength region. Additionally, the divided cell strips were interconnected via ECA bonding, and the characteristics were investigated. The interconnected cell exhibited the efficiency of 18.302% while the efficiencies of two cell strips were 18.039% and 18.162%, respectively.