R&D planning is important for promoting R&D effectively and efficiently. The authors formulate planning of R&D on solar cells as an optimal resource allocation problem by using mathematical programming. The optimal resource allocation model based on this formulation includes technological progress submodels of solar cells and production and market submodels of solar cells. This model is expected not only to make clear the validity of R&D strategy on solar cells in the past, but also to give us the optimal plan of R&D on solar cells in the future. (C) 2001 Elsevier Science B.V. All rights reserved.