Editor's Desk From the

‘Solar’ is the Latin word for ‘Sun’ and the Sun is the fount of all energy on Earth. It is the source of life for plants, the cause of flow in the atmosphere and waterit is what makes life possible. None can exist without it. Each square metre of Earth facing the Sun receives about 1380 joules of energy. This quantity is known as the solar constant. Solar technologies are broadly characterised as passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful output. Passive solar techniques include selecting materials with favourable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies. In 2011, the International Energy Agency said that ‘the development of affordable, inexhaustible and clean solar energy technologies will have huge long term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered investments; they must be wisely spent and need to be widely shared’. The utilisation of solar energy in India has seen a new dimension with solar energy based grid power generation. Today, the installed capacity for solar grid power has reached over 1040 MW and the major part of it came in the last two years with the launch of the Jawaharlal Nehru National Solar Mission. It is poised to take a leap to about 20000 MW by the year 2022. The current issue is focused on solar energy. Articles in the issue present a range