Information About Solar Panel Efficiency
Solar panel efficiency; It is determined by the power produced in 1 m2 area when radiation is applied to the panel under standard test conditions (1000 W/m2). For example; A panel on a 1m2 cell area with 15% efficiency generates 150 W/h electricity when 1000 W/m2 of daylight is received vertically. The efficiency of the solar panel; It varies depending on the cell type used, cell design and quality, and the quality of glass and other components.
Since the average radiation value in our country is at the level of 1300 W/m2, it is possible to produce above the standard efficiency rates of the panels. Crystal panels have an efficiency between 16% and 24%, and thin-film panels have an efficiency between 10% and 15%. In parallel with the development of technology, cell productivity increases every year. Although there are solar panel prototypes with 45% efficiency as a result of scientific studies, they are only used for special occasions (space studies, etc.) due to the high cost.
The efficiency of solar panels decreases at a slow rate over their lifetime. Factory productivity rate for the first 10 years measured under standard test conditions; Values such as 10% reduction between 10 and 20 years and +10% reduction between 20 and 30 years are given by the manufacturers as performance guarantees. For example, a solar panel with an efficiency of 17%; While it shows an efficiency of close to 17% at the end of the first 10 years, this value may decrease to 15% in the 20th year, and to 10% when approaching the 30th year, which is considered to be useful life. Difficult environmental conditions and not cleaning the panels frequently are also important factors in decreasing panel efficiency.
The Effect of Location and Weather Conditions on Solar Panel Electricity Production
The average solar radiation value in our country, which is 1300 W/m2, varies according to the geographical location and varies according to whether the weather is clear, cloudy or rainy.
For example, considering that the average radiation in Ankara is 800 W/m2; It can be predicted that the amount of radiation will be 1000 W/m2 in clear weather, 200 – 750 W/m2 in cloudy weather, and 50 W/m2 in rainy weather. A solar energy system consisting of polycrystalline panels with a total power of 1 kW and an efficiency of 18%; It will produce 1 kW of electricity in clear weather, 0.5 kW in cloudy weather and 0.05 kW in rainy weather. The same values are approximately for Antalya province; It will be 1.15 kW in clear weather, 0.6 kW in cloudy weather and 0.06 kW in rainy weather.
As seen in the example; Solar panels also produce electricity on cloudy days. Even if the solar panel does not receive direct sunlight, it produces a certain amount of electricity every time it receives daylight. Since the amount of light is minimal in rainy weather, the amount of electricity produced is not sufficient to fill the batteries in off-grid systems. For this reason, the number of consecutive rainy days in the region should be taken into account while designing the solar energy system.