Solar panel efficiency: what is it?

Solar panels can lower utility bills and produce clean, environmentally friendly energy. But what makes them efficient? The efficiency of photovoltaic solar panels is related to the quality of their photovoltaic (PV) cells. The conversion efficiency of a PV cell is the percentage of solar energy shining on a solar panel that is converted into usable electricity. The more efficient a solar panel is, the more energy output it will have per amount of light hitting the cell, which will in turn take up less surface area to meet your energy requirements.


What factors affect solar panel efficiency?

The efficiency of the PV cells that make up a solar panel is based on energy from sunlight that is converted into electricity through the process of photovoltaics. An efficient solar panel is one that generates more electricity by occupying less space. A cell's efficiency can be increased by minimizing the amount of light reflected away from the cell's surface. Other factors that affect the average efficiency of solar panels include the intensity of the sun, the amount of cloud cover and heat build-up, which affects the conductivity of the semiconductors in the PV cells.


Do solar panels lose efficiency over time?

Solar panels slowly degrade over time, meaning that they produce less electricity from the same amount of sunlight. The causes of solar panel efficiency degradation include wear and tear due to weather. The average productive life of solar panels is 30 years. According to the National Renewable Energy Laboratory (NREL), solar panels and their output degrade at a rate of about 0.5% per year: a 20-year-old panel will produce approximately 90% of the electricity it produced in its first year of life.


Are solar panels efficient in winter?

Solar panels generally only produce electricity when the sun is shining. Obviously, there is less direct sunlight in winter than in summer, so solar panels produce less electricity during the cold season when days are shorter. Although solar panels are more efficient in summer, they can still generate enough electricity to heat your home in winter. One way to make sure of that is to pair solar panels with energy storage systems made up of batteries. This way you can store excess energy produced by your solar panels to power your home at night, or on a rainy day.

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