Did you know that the amount of sunlight that hits the earth’s surface in an hour and a half is enough to handle the world’s energy consumption for a full year? Solar energy has amazing potential to power our daily lives thanks to ever-improving technologies.

Solar energy systems come in all shapes and sizes. Residential systems are on the rooftops of the United States and companies are also choosing to install solar panels to offset their energy costs. Utilities are also building large solar power plants to provide cleaner energy to all customers connected to the grid.

There are two main types of solar power technologies: photovoltaic (PV) and concentrating solar power (CSP). You are probably more familiar with photovoltaic energy, which is used in panels. When the sun shines on a solar panel, photons from sunlight are absorbed by the cells of the panel, creating an electric field through the layers and causing electricity to flow.

The second technology is Concentrating Solar Power or CSP. It is mainly used in very large power plants and is not suitable for residential use. This technology uses mirrors to reflect and focus sunlight onto receivers that collect solar energy and convert it into heat, which can then be used to produce electricity.

Every place on Earth receives sunlight at least part of the year. The amount of solar radiation that reaches any point on the Earth’s surface varies according to:

Geographic location

Time of the day

Station

Local landscape

Local climate.

Because the Earth is round, the sun hits the surface at different angles, ranging from 0 ° (just above the horizon) to 90 ° (directly above). When the sun’s rays are vertical, the Earth’s surface receives as much energy as possible. The steeper the sun’s rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. Because the Earth is round, the icy polar regions never get a high sun, and because of the tilted axis of rotation, these areas get no sun at all for part of the year.

Earth revolves around the sun in an elliptical orbit and is closest to the sun for part of the year. When the sun is closer to Earth, the Earth’s surface receives slightly more solar energy. Earth is closest to the sun when it is summer in the southern hemisphere and winter in the northern hemisphere. However, the presence of vast oceans moderates the hottest summers and coldest winters that one would expect to see in the southern hemisphere as a result of this difference.

The 23.5 ° tilt on the Earth’s axis of rotation is a more significant factor in determining the amount of sunlight striking the Earth at a particular location. The tilt results in longer days in the northern hemisphere from the vernal equinox to the autumnal equinox and longer days in the southern hemisphere for the other 6 months. Days and nights last exactly 12 hours on the equinoxes, which occur each year around March 23 and September 22.

Countries like the United States, which are located in the middle latitudes, receive more solar energy in the summer, not only because the days are longer, but also because the sun is almost overhead. The sun’s rays are much more skewed during the shorter days of the winter months. Cities like Denver, Colorado (near 40 ° latitude) receive almost three times more solar energy in June than in December.

The rotation of the Earth is also responsible for the hourly variations of sunlight. Early in the morning and late in the afternoon, the sun is low in the sky. Its rays travel further through the atmosphere than at noon, when the sun is at its highest. On a clear day, the greatest amount of solar energy reaches a solar collector around solar noon.