Mahsa Esmaili - BSc Student of Green Space Engineering from Mohaghegh Ardabili University

Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy including solar water heating, and solar architecture. It is an essential source of renewable energy, and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power, and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air. The large magnitude of solar energy available makes it a highly appealing source of electricity. In ۲۰۲۱, Carbon Tracker Initiative estimated the land area needed to generate all our energy from solar alone was ۴۵۰,۰۰۰ km۲- or about the same as the area of Sweden, or the area of Morocco, or the area of California (۰.۳% of the Earth's total land area). The Earth receives ۱۷۴ petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere. Approximately ۳۰% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and nearinfrared ranges with a small part in the near-ultraviolet. Most of the world's population live in areas with insolation levels of ۱۵۰–۳۰۰ watts/m۲, or ۳.۵– ۷.۰ kWh/m۲ per day. Solar radiation is absorbed by the Earth's land surface, oceans – which cover about ۷۱% of the globe – and atmosphere. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anticyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of ۱۴ °C. By photosynthesis, green plants convert solar energy into chemically stored energy, which produces food, wood and the biomass from which fossil fuels are derived.

Solar energy, solar power, solar design, thermal energy, global warming