Eco-friendly minimodules made of n-type Aluminum rear emitter solar cells

We present one-cell-modules made of n-type Cz-Si solar cells with rear Al emitter. Cells are fabricated in an industrial like environment; the interconnection tabs are applied by bonding a conductive adhesive film; modules are made with an industrial type laminator. To our knowledge these are the first modules made from cells with this architecture.The main benefits of this module structure are that the conductive film used for bonding the tabbing is completely lead free, already fulfilling now future RoHS standards (restriction of hazardous substances). Additionally, the cells are completely boron-free which guarantees stable efficiencies when exposed to light.We evaluate different interconnection schemes focusing on the rear side. For that purpose the already fired Al paste on the rear is locally abrased and an interconnection tab is applied by conductive film bonding. With this simple method shunting of the Al emitter has been avoided and the interconnection of cells to strings can be realised with one less process step as compared to conventional p-type Al BSF cell production.Using the above mentioned cells and methods we produced one-cell-modules to prove stable cell interconnection. Individual cells are characterised with IV measurements after co-firing, with bonded tabbing and as a one-cell-module. Finally we performed climate chamber tests. Three modules with different rear architecture are used for damp heat tests and another two for temperature cycle tests (according to DIN EN 61215). For both tests one individual rear configuration is well within the test specifications.