Solar Energy Potential and Utilization

Solar Energy Potential and Utilization

In addition to being free as a source of energy (it does cost money to harness it and turn it into electricity), energy from the sun is practically limitless. The surface of the Earth receives solar energy at an average of 343 W/m². If we multiply this times the surface area of the Earth, about 5x10¹⁴ m², we get 1715x10¹⁴ W. But, 30% of this is reflected, and only 30% of the Earth is above sea level, so the usable solar energy we receive on the land surface is about 360x10¹⁴ W. We need to reduce this further because not all of the land surface is suited to installation of solar PV panels — we don't want to cut down forests, and ice-covered areas are not suitable, so we reduce the area by about one half. Over the course of a year, this amount of solar energy adds up to 66x10²² Joules. In 2018, we used about 600x10¹⁸ Joules of energy, which is just a shade less than 0.1% of the harvestable solar energy we receive on the land. This means that even if we got all of our energy from the Sun, we would not make a dent in the total! The potential is vast — 10,000 times what we need!

Let’s consider what it would mean for us to get all of our energy from Solar PV — how much of the Earth’s surface would we need to cover with panels? The black dots (radii of 100 km) in the figure below represent areas that could generate enough energy from sunlight to completely power the planet for an entire year. Practically, there are barriers to running the planet entirely on sunlight (everything would need to be electrified, we would need very large quantities of battery energy storage, and so forth), but the dots are useful as a demonstration of just how vast the energy production potential from solar is.

Global average solar irradiance. Areas in red have a higher-strength solar energy resource on average. The black dots indicate areas with sufficient solar energy potential to supply the entire world’s energy demands.

Click here for a description of the Global average solar irradiance image.

This image is a world map illustrating the annual mean solar potential across the globe, measured in watts per square meter (W/m²). The map is sourced from Matthias Loster, 2006, and includes a total solar potential estimate of 18 terawatt-equivalents (TWe) indicated in the bottom right corner with the symbol "Σ⦿ = 18 TWe."

Map Overview:
The map shows a global view with continents outlined in black, including North and South America on the left, Africa in the center, Europe and Asia above, and Australia on the right. The background is a gradient of colors representing solar potential, with a color scale at the bottom ranging from purple (lowest) to red (highest)

• Color Scale:
  The color bar at the bottom ranges from 0 to 350 W/m². Purple represents the lowest solar potential (0–50 W/m²), transitioning through blue (50–100 W/m²), green (100–150 W/m²), yellow (150–200 W/m²), orange (200–300 W/m²), and red (300–350 W/m²) for the highest solar potential.
• Solar Potential Distribution:
  • High Solar Potential (Red/Orange): Areas with the highest solar potential (250–350 W/m²) are concentrated near the equator, including Central Africa, the Middle East, northern Australia, and parts of the central Andes in South America. These regions appear in shades of red and orange.
  • Moderate Solar Potential (Yellow/Green): Moderate solar potential (150–250 W/m²) spans much of South America, Southern Africa, India, Southeast Asia, and northern Australia, shown in yellow and green shades.
  • Low Solar Potential (Blue/Purple): Areas with the lowest solar potential (0–150 W/m²) include the polar regions, northern North America, Northern Europe, and parts of Russia, depicted in blue and purple shades
• Black Dots:
  Several black dots are scattered across the map, likely representing specific locations or solar energy projects. These dots are located in the southwestern United States, central South America, central and Southern Africa, the Middle East, India, and northern Australia.
• Additional Details:
  The map uses a gradient color scheme to visually represent the intensity of solar potential, with equatorial regions showing the highest potential due to their proximity to the sun’s direct rays. The source, "Matthias Loster, 2006," is noted in the bottom right corner.

It’s kind of amazing to see how little area of the Earth would need to be covered to achieve this.

Source: Total Primary Energy Supply(link is external)

One of the important differences between Solar PV and CSP is that CSP requires more intense sunlight, and as such, it is not a viable option in many places. In contrast, Solar PV works just about everywhere — it is more versatile. Another important difference is in scale — CSP is really suited to utility-scale power plants, whereas Solar PV works at both the utility-scale and the very small scale.

The map below shows the PV potential for the world. The variability in the map is mainly a function of cloudiness and latitude. Many of the big, utility-scale solar PV plants are located in the red areas, but there is a surprising amount of Solar PV energy being harvested in places like Germany and Japan, both of which are fairly cloudy. But, even in a fairly cloudy place like Pennsylvania, you can see from the map that we could expect about 1460 kWh per year from a 1 kW PV array. From this, you can calculate how many square meters of PV panels you’d need to provide the electricity for a house that uses the typical 10,800 kWh per year. If you divide 10,800 kWh by 1460, you see that you’d need about 7kW of solar panels, which would fit on a typical house roof. The main point here is that Solar PV is a viable energy source in most parts of the world where people are living. In contrast to Solar PV, energy from CSP is only viable in places where the daily totals in the map above are higher than 6 kWh/day. Nevertheless, there are many regions where CSP viability and human population coincide, so it too can be an important energy resource in the future.

This world map from the World Bank Group’s Global Solar Atlas shows the estimated potential for Solar PV energy in terms of kWh energy produced from a solar PV array of 1 kW. It is important to understand that daily totals are an average value — the output each day will vary according to how cloudy it is and how high in the sky the Sun is. The yearly totals are just the daily total times 365.

Click for a text description of the Photovolitic power potential map.

The image is a world map titled "Solar Resource Map: Photovoltaic Power Potential," displaying the global distribution of photovoltaic power potential. The map uses a color gradient to indicate the long-term average of photovoltaic power potential (PVOUT), measured in kilowatt-hours per kilowatt-peak (kWh/kWp). Areas with higher potential are depicted in shades of red and orange, while lower potential areas are shown in blues and greens. Notably, regions such as North Africa, the Arabian Peninsula, and parts of Australia show high potential with intense red and orange hues. Northern Europe and parts of Canada show lower potential with blue and green shades. A scale beneath the map indicates the PVOUT values ranging from 2.0 to 6.4 kWh/kWp. Below the scale, yearly totals are listed from 730 to 2337 kWh/kWp. Logos of the World Bank Group, ESMAP, and Solargis are displayed at the top right.

Credit: Global Solar Atlas(link is external)