We analyse the status and the trends in the growth of renewables in India. We propose a methodology linking micro-simulation to macro-modelling to obtain technical and economic potential estimates for solar water heaters in residential and commercial and biomass gasifiers for thermal applications in industry. We assess the sustainability of renewables based on the criteria of life cycle cost, net energy ratio, resource constraint and greenhouse gas emissions. The renewable based technologies seem to be sustainable based on all criteria, except the high life cycle cost. In some cases e.g. in wind and biomass based systems land availability may constrain sustainability. Biomass is likely to be a sustainable solution only if marginal/scrub lands can be used for biomass plantation with adequate yield. We discuss the barriers to adoption of renewables and policies required for widespread diffusion.