We present the results of three novel approaches to the fabrication of kesterite solar cells from scalable, Cu2ZnSnS4 (CZTS) nanoparticle inks. Firstly, CZTS nanoparticles are annealed in a Se-rich atmosphere inside a transmission electron microscope (TEM). This allows observation of the thin film PV absorber formation in real-time and provides the new insight that chalcogen atom exchange and grain growth occur in different temperature regimes. Secondly, we demonstrate an approach to alkali doping Cu2ZnSn(S,Se)4 PV absorbers on flexible Mo-foil substrates that is compatible with high volume manufacturing. Adding NaF directly to the CZTS nanoparticle ink promotes grain growth and improves the device efficiency to 4.4%. Lastly, In2S3/CdS dual buffer layers are investigate to reduce the usage of Cd and result in device efficiency of 7.8% on a glass substrate.