The amount of solar energy reaching the earth each year corresponds to more than 10 000 times the earth’s total energy consumption. By covering 0.4% of the country with solar cells, today’s solar cell technology (15% efficiency) can provide Norway with 120 TWh annually. A similar value is also pertinent for the United States. It is therefore possible to utilise solar cells in order to supply all of our electricity consumption, given that we find a good way to store energy for utilization at night or in cloudy weather.
Solar heating can be used directly in buildings in either passive or active systems. This is often a very cost-effective way to heat buildings, even in sun-deprived regions as Norway. Solar heat might also be used directly for cooking, and sunlight can be used to replace electric lighting in office buildings.