First purchase sales volume curve of box type solar cooker indicated that the product has passed maturity in Gujarat. We have initiated collaborative redesign work to improve the product. Central element of redesign concept is the addition of an electrical back up. This will enable users to cook food even when insolation and or ambient temperatures are low. It is hoped that this will enhance the appeal of the cooker. It is important to estimate the market potential and the likely growth trajectory of the 'new' cooker. One of the ways suggested in marketing literature is to identify an existing product which may be 'analogous' to the new product and use it to draw diffusion related inferences. This is the aim of the present work which will be reported in two parts. In this first part, we review works relating to diffusion of products in India and present results of using Bass model to describe the growth of the present cooker. In the second part to be reported later, we will explore the use of diffusion models as aid to identify product analogues.