Geographic location plays a major role in solar energy production. Solar insolation, which is the amount of energy harnessed annually per square metre, greatly varies worldwide.
Latitude and sunlight intensity
Latitude is a measure of how far north or south a place is from the Earth’s equator and it plays a significant role in solar intensity.
Near the equator, sunlight beams down almost directly, providing a higher concentration of solar energy. Closer to the North and South Poles, sunlight hits the Earth more obliquely, spreading over a larger area and losing its intensity.
This is why solar panels in tropical regions can produce more energy than those in higher latitudes.
Insolation in London reaches 1,100 kWh/m^2, in New York, it’s 1,300 kWh/m^2, and in the Sahara, it’s a considerably higher 2,800 kWh/m^2. This figure varies widely, even in the UK.
Seasonal shifts and day length
The tilt of the Earth’s axis causes daytime lengths to vary as the Earth orbits the sun. Longer summer days offer more sunlight hours, maximising solar energy potential.
Shorter winter days in high-latitude regions offer drastically reduced sunlight hours and less potential energy. It’s not just about the total hours of daylight, though.
Peak sunlight hours are especially crucial. A summer day might be long but nevertheless have a relatively short period in which solar generation conditions are ideal. For example, London receives 0.52kWh/m2 of solar energy per day in December and 4.74kWh/m2 of solar energy per day in July.
The amount and intensity of sunlight are just one part of the solar energy equation. Local weather conditions and climate are another. They can either boost or hinder solar panel efficiency.
Clouds, fog and precipitation can obstruct sunlight, decreasing solar output. Solar panels still function on cloudy days but have a lower efficiency than they do when the weather is clear and sunny.
We associate solar panels with bright, sunny conditions, but temperature also affects the panels’ efficiency. Extreme heat can reduce a solar panel’s performance. So, in regions such as the Sahara, the impact of impressive solar intensity is partly diminished by the effects of extreme heat. Cooler, sunny days in other parts of the world can offer better conditions for solar panels.