Approximately 174 petawatts (PW) of solar power reaches the outer atmosphere of Earth. However, not all of this energy reaches the surface due to various factors. The percentage of the Sun's energy that ends up reaching the Earth's surface depends on multiple factors, including atmospheric effects, Earth's albedo (reflectivity), and cloud cover. On average, about 70% of the solar energy that reaches the Earth's outer atmosphere actually makes it to the surface.
The remaining 30% is reflected back into space or absorbed and scattered by the atmosphere. Some of this energy is reflected directly by clouds, aerosols, and the Earth's surface, while another portion is absorbed by the atmosphere itself. Ultimately, this percentage can vary depending on factors such as geographic location, time of day, season, and weather conditions.
It's important to note that the percentage of solar energy reaching the Earth's surface refers to the total solar radiation, including visible light, ultraviolet (UV) radiation, and infrared (IR) radiation. Different portions of the solar spectrum are absorbed or interact with the atmosphere and surface in varying ways. For example, the Earth's atmosphere partially absorbs some UV and most of the IR radiation, while visible light passes through more readily.
Overall, while about 70% of the Sun's energy reaches the Earth's surface, it still provides an abundant and vital source of energy that sustains life, drives weather patterns, and supports ecosystems on our planet.