Solar radiation is often known as the solar resource or just sunlight. Is a generic term for the electromagnetic radiation emitted by the sun. Solar radiation can be captured and transformed into different types of energy, such as heat and electricity, using a variety of technological devices. Nevertheless, the efficiency of these technologies at a specific location depends on the available sunlight.
Main factors to consider
Every location on the planet receives sunlight at least half of the year. The amount of radiation that reaches any one spot on the Earth’s surface can vary due to several factors:
- Geographic location
- Time of the day
- Season
- Local weather conditions
- Local landscape
Due to the Earth’s shape (round), the sun strikes the surface at different angles (from 0° to 90°). At the moment when the sun’s rays are vertical, the planet’s surface gets the maximum amount of energy. The more slanted the sun rays are, the longer they will travel through the atmosphere. Becoming more scattered and diffuse.
The Earth revolves around the sun in a specific orbit called “the elliptical orbit”. Which is closer to the sun during part of the year. So when the sun is closer to the planet, the surface receives more solar energy. The season in which the planet is placed near the sun is during the summer in the southern hemisphere and during the winter in the northern hemisphere. However, the climate is not that cold nor that hot due to the vast oceans which moderate the hotter summers and colder winters.
A great example of this is the United States, located in the middle latitudes, which tend to receive more solar energy in the summer not only due to longer days during this season but because the sun is nearly overhead. The sun’s rays are more slanted during shorter days like during the winter months. And so, cities such as Denver and Colorado will receive nearly three times more sunlight in June than they do during December.
Source: Office of Energy Efficiency and Renewable Energy