Electrical Output
Currently, solar panels are too inefficient to replace fossil fuel electricity generation around the world. For simplicity, let's evaluate the total electrical output of solar technology in two ways: electricity production and storage capacity.
Electricity Production
To put it bluntly, solar cells don’t produce nearly as much electricity as fossil fuels do. A Tesla solar panel, for example, can produce a maximum of 340 W of electricity when placed in perfect sunlight conditions. On an average day in New York, this panel would produce about 1 kWh of electricity. On the other hand, burning 1 ton of coal will produce an average of about 2,460 kWh of electricity. This means that to eliminate the use of coal, the most dangerous fossil fuel for the environment, we would need around 2,460 Tesla solar panels to replace every ton of coal burned. For reference, billions of tons of coal are burned each year. The amount of electricity one solar panel can generate must improve drastically if the world wants to use them as a viable alternative to fossil fuels.
There are many factors that limit the electricity production of solar panels, including band gap energy and geographic and seasonal conditions. The amount of sunlight that hits a solar panel each day is one of the determining factors of how much electricity it produces. A solar panel’s subjection to sunlight can vary depending on seasonal and daily weather, as well as a panel’s position relative to the sun. By position, I mean that a panel could be on a slanted roof, or it could be flat and facing upwards.
The coal-powered Four Corners Power Plant in New Mexico.
Image: The Arizona Republic
The geographic location of a solar panel will effect the amount of sunlight it receives as well. A solar panel in London, a generally cloudy place, will receive less sunlight than one in Florida. As a result, the Florida panel will generate more electricity than the London one, and will be more useful. The differences in sunlight that solar panels receive depending on their location makes the electrical output of solar technology unreliable. This unreliability has caused solar panels to struggle to compete with other forms of energy generation.
Average monthly hours of sunshine in London, England.
Image: Weather & Climate
Average monthly hours of sunshine in Miami, Florida.
Image: Weather & Climate
Three popular solar batteries: the LG Chem RESU (left), sonnenCore battery (center), and Tesla Powerwall (right).
Image: Solar Reviews
Storage Capacity
Sometimes, solar panels will generate more electricity than a building needs. To avoid wasting energy, excess electricity is stored in solar batteries, and is used at times when solar cells can’t produce electricity, like the nighttime or on cloudy days. Most solar batteries today, however, don't have large storage capacities. Because of this, homeowners with solar panels often run out of stored energy during less sunny times of the year, and are forced to rely on local energy providers to continue to power their homes.
The improvement of thermal energy storage—the storage of electricity produced by solar panels—is vital to increase the overall efficiency of PV technology. Without an effective way to store the energy solar panels generate, much of their electrical yield is wasted.
References
Lane, Catherine. “What Is the Best Solar Battery for Your Home?” Solar Reviews, Solar Reviews, 6 Apr. 2021, www.solarreviews.com/blog/is-solar-battery-storage-worth-it-given-current-solar-battery-cost#tesla-powerwall.
Randazzo, Ryan. “Coal-Burning Four Corners Power Plant Will Cut Back on Operations, APS Says.” The Arizona Republic, Arizona Republic, 12 Mar. 2021, www.azcentral.com/story/money/business/energy/2021/03/12/aps-four-corners-power-plant-reduce-operations-one-generator/4655198001/.
“Solar Panels: Tesla.” Tesla, Inc., www.tesla.com/solarpanels.