The concept of agrivoltaic, combining agriculture and solar photovoltaic system, is ideal for populous countries like India as it provides access to eco‐friendly power and crop production from the same land. The main objective of the study was to evaluate the performance of agrivoltaic systems for different geometry of solar photovoltaic strings and their suitability for agricultural practices for the greengram (Vigna radiata L. Wilczek) crop under North‐Gujarat agro‐climatic conditions of India. Eight equal‐capacity strings with different geometry were designed to evaluate power generation and crop production beneath the strings. The experiment involved eight strings taken as eight treatments and the traditional system of greengram (V. radiata L. Wilczek) cultivation practices is taken as the ninth treatment. The greengram (V. radiata L. Wilczek) was shown and all other cultural practices was kept same upto grain yields. The results revealed that 10.5 feet height string with continuous solar panel pattern) provided the highest gross income (Rs. 24,364.00) from power generation and greengram (V. radiata L. Wilczek) yield. In terms of net realization, a 6.0‐feet string with continuous solar panel pattern provided the highest net return of Rs. 12,417.00, as the capital cost was less for the system. Treatment‐5, which involved transparent panels, was found to be better for the photosynthesis process of the greengram (V. radiata L. Wilczek) crop, as it provided the highest yield (12.99 kg) under the agrivoltaic system.

In order to determine the working efficiency and economical size of biogas plants in respect of house hold cattle and family members, a study was carried out during 2007-08 in Chhattisgarh State, India. Fifteen blocks were selected randomly covering 117 biogas plants. Out of them, 99 plants (85 %) were found in working condition for which economic analysis was carried out. Survey results revealed that economically different sizes of biogas plants i.e. 2- 8 m3 were useful in the study area. On an average, the whole initial investment could be recovered in an about 3- 8 years. The annual income of different size of biogas plants from 2 m3, 3 m3, 4 m3, 6 m3 and 8 m3 will be Rs 3620, Rs 5273.6, Rs 4215, Rs 4565 and Rs 4612, respectively. The cost of operations of different size of biogas plants (2-8 m3) were observed in the range 2.73- 4.0 Rs/h. The size of most economical biogas plant was 3 m3 (B/C= 1.23) followed by 2 m3 (B/C= 1.06).