Thin film solar cells of β-FeSi2(Al)/Si heterojunctions were fabricated via Al incorporation and rapid thermal processing (RTP). The Al-incorporated FeSi2 films were polycrystalline, orthorhombic and semi-conducting. Photo-voltaic characterisation showed that device prepared with Al interlayer added between Al-doped FeSi2 film and Si exhibited short-circuit current and open-circuit voltage improvement over device without interlayer. These can be correlated to surface passivation of Si by interfacial structure and reduced dark current with Al interlayer. This alternative fabrication method via Al incorporation to β-FeSi2 films using conventional magnetron sputtering and RTP enhances the viability of β-FeSi2 for photovoltaic application.