Solar Panel Efficiency

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What is solar panel efficiency?

A solar panel’s ability to turn the amount of sunlight absorbed on its surface into electricity is defined as solar panel efficiency. Solar panels use materials like silicon, gallium arsenide, cadmium telluride, perovskite, and others as semiconductors. Each material has different efficiency levels, costs, and accessibility. The most used PV material is silicon because it is cheap and widely available. If solar panels are manufactured with high efficiency, a solar owner doesn’t need as many solar panels to get the same amount of energy. An efficient solar panel can also reduce all the component costs of a solar system, such as wiring, switches, inverters, batteries, meters, and charge controllers.

How efficient are solar panels?

Current PV solar panels made of crystalline silicon reach up to22% efficiency levels, a big leap from a10% efficiency in the 1990s, as illustrated in the graphic.

 Panel efficiency over time

Source:Lafayette College

Crystalline silicon is the leading semiconductor material for solar panels because it is affordable, widely accessible, and maintains high performance. The years of research on silicon’s use in the computer industry have also helped the solar industry hone its knowledge about silicon as the most cost-effective and reliable semiconductor for PV solar cells.

What factors affect the efficiency of a solar panel?

All the sunlight reflected on a solar panel doesn’t convert into usable energy; most of it is typically lost. The following solar panel elements determine the most efficient way of turning sunlight into electricity:

• Temperature. Low atmospheric temperature increases the efficiency of solar panels, while a high temperature reduces it. Heat can increase the current in a solar panel but lower the voltage it can generate, reducing its efficiency. Extreme heat can harm solar cells and shrink their lifespan.
• Wavelength. Sunlight has a broad range of wavelengths. When sunlight hits a solar panel, some, but not all, of its particles, known as photons, produce charge carriers and create an electric current. Semiconductor type and solar cell design determine the ability of a solar cell to capture and convert photons into electricity most efficiently.
• Reflection. Simply put, light reflected off solar panels is uncaptured and lost energy. The more light is reflected on a solar cell surface, the less efficient it is. Silicon-made solar cells are naturally reflective. Solar panels with silicon semiconductors use an anti-reflective coating to convert captured photons into energy more efficiently.
• Recombination. A process in which an electron on a semiconductor falls into a “hole” before it gets collected in a solar cell is known as recombination. The absence of a negatively charged electron fails to contribute to the electrical current across the semiconductor. Recombination can happen on semiconductors with impurities and defects during solar panel manufacturing.
• Roof angle and orientation. Solar panels on south-facing roofs with a tilt of 30 to 40 degrees operate most efficiently in North America because they get the most direct sunlight year-round. Solar panels installed at an angle also help snow slide off easily during the winter. However, even if your solar system doesn’t face south, it can still generate enough energy to meet your needs and save you hundreds of dollars annually.
• Shading. If sunlight doesn’t reach solar panels due to partial or complete shading, it prevents them from generating energy and operating to their maximum efficiency. Shading can lead to power losses as solar cells are connected for maximum voltage. Shading one solar cell can reduce the electrical current and voltage of all other cells and compromise their efficiency.
• Upkeep. Solar panels are generally built to last up to 30 years. They don’t require much maintenance during their lifespan, but it is essential to clean them periodically since an accumulation of dirt can reduce their efficiency. Inspection for any damages and regular cleaning can help your solar panels absorb sunlight more efficiently and generate the maximum amount of electricity.

What types of solar panels are most and least efficient?

The most common solar panels are made from crystalline silicon. While the concentrator PV technology leads crystalline silicon in efficiency, it’s more expensive and less feasible for residential energy use. Here are the main characteristics of each crystalline silicon solar panel. 

Curious about solar panel types and what suits best for your needs? SaveOnEnergy provides you the answers: