With the rapid growth of cities, the need for a renewable source of energy is increasing. Simultaneously, the growth of cities has left limited space for installations of renewable energy sources which require a large area. Similarly, installations of large renewable energy farms on the outskirts of cities and rural area leave less space for the farmers for agriculture which is again a primary need for the country. Therefore, there is a need to find a solution to achieve higher energy generation per unit area of land. Moreover, there is a large deviation in the solar energy distribution pattern between various months due to varying solar insolation. Hence, it is desirable to achieve a relatively uniform energy generation throughout the year. The current project aims to design a solar tree where solar panels are appropriately positioned similarly to the leaves of a tree. Compared to fixed orientation solar panels, the main advantage of a solar tree is the ability to optimize the orientation and position of individual solar leaves in order to obtain the required power generation curves, for example, increasing the energy production during the winter months when solar insolation is low. The analytical study has shown that there is scope for location specific design of solar tree to alter the energy generation curve as desired.
The design of a 500 W tree structure (consisting of five 100 W panels as shown in Fig. 1) was optimised for the city of Delhi such that energy generated in the low energy months is improved without compromising too much on the energy generated during high solar insolation summer months. The tree design also takes care of minimizing the shadowing effects of one panel on the other as the sun moves across the sky. Detailed analytical calculations leveraging genetic algorithms were performed to find the optimised angles and positions of the solar leaves for efficient energy generation. Further, analytical calculations were validated with ray optics simulations showing excellent agreement. As shown in Fig. 2, the tree design offers a gain of 15.06% in received energy in the months of November to February. At the same time, it provides a gain of 1.15% in received energy in the rest of the year compared to a horizontal panel ground mounted system. The tree configuration is expected to generate 1226.54 kWh annually in Delhi. Future studies would include optimisation of the solar tree for Bombay and Chennai and fabrication of the same by Central Electronics Limited, Delhi as a part of consultancy project.
Fig. 1: CAD Model of Proposed Solar Tree
Fig. 2: Comparison of energy generarion curve of proposed design with horizontal panels