Comparing and Optimizing of Solar Insolation on Yearly, Monthly and Seasonally Basis for Solar Devices Performance in Nepal

Rijan Karkee, Sumit Khadka, Gaurav Luitel, Mausham Devkota, Bibek Khadka, Shushilata Sapkota, Puja Bhetwal

Solar Photovoltaic panels and solar water heating systems are the most used form of harnessing solar energy (utilizing both diffuse and direct radiation) and evidently, the power harnessed by the system is dependent on location, time of the day, the amount of sunshine hours, cloud cover etc. The orientation of the solar energy harnessing devices is another important factor and in fact, the factor that can be easily controlled for maximum power harnessing. This paper presents the calculation of the optimal tilt angle of solar energy devices according to different month, seasons (summer and winter) as well as for a year based on average data of insolation previously recorded for 5 different places of Nepal (latitude 26.45⁰N  to 29.27⁰N). Furthermore, the solar insolation for yearly fixed optimal tilt angle versus seasonal tilt angles has also been discussed and is compared.