Which Factors Determine the Efficiency of Solar Panels

Solar power systems are considered a key tool in the energy supply. An important metric that is used to compare the performance of solar panels is the solar energy conversion efficiency. This is the ratio of the amount of electricity produced by the system to the amount of solar energy that it captures. This is an important parameter, since most of the sunlight that hits the photovoltaic cell of the solar panel is scattered without being converted into electricity. Currently, the efficiency of solar modules is 22%, although this figure could potentially reach 90%.

Before investing your money in the purchase and installation of a solar energy system that can provide your household with the necessary amount of electricity, it is important to determine the panel efficiency. The higher this figure, the faster your costs will pay off. Due to errors in installation and operation, the installed structure may work with less productivity. To prevent this, you need to know what factors determine the efficiency of solar panels and how to increase this figure.

What are the Factors that Affect Solar Panel Efficiency?

Solar panel efficiency would depend on several conditions. The performance of a home power plant depends on the quality of the modules and the weather conditions in which the system operates. For example, the level of electricity generation by mono crystalline panels is 18-22%, and by polycrystalline – only 13-17%. The rest of the sun’s rays are lost due to reflection from the silicon wafers of the structure and their heating. The level of solar energy conversion also depends on the material of the modules. Silicon panels have the highest performance index (17-22%) when properly used.

The efficiency of the panel is usually indicated in the passport of the solar battery and is calculated by dividing the power of the received electricity by the power of solar energy per a certain area of the panel. This parameter, along with other characteristics, is determined under standard conditions (STS), the main ones being insolation (1000W/m2) and element temperature (250С). Knowing this indicator, you can correctly calculate the required number of panels to create a productive solar power plant.

How to test a solar panel by its technical characteristics? Its performance can be calculated using the solar cell efficiency formula: Efficiency = P: S: 10, where P – battery power; S – its area.

The manufacturer issues the technical characteristics of the module (Fig.). Among them we find the maximum power of the structure (104, 617 W). According to the formula, with a battery area (1.2 x 0.554) m2 its performance will be 15.74%. 

The effectiveness of the panel is also affected by such factors:

  • structure heating temperature and day length (maximum performance is observed at 250C in summer);
  • slope of the panels (they must face the sun and be located on a shed roof in a southerly direction);
  • shading, and a partial shadow on the panel has a worse effect on energy production than a full one;
  • the angle of incidence of the sun’s rays (the performance of the panel is maximum if the rays fall on its surface at an angle of 900). To do this, it must be tilted at an angle of 340 relative to the horizon;
  • cleanliness of the working surface (it must be installed in such a way that precipitation and dirt naturally drain from it);
  • weather conditions (in cloudy weather, the efficiency of the module decreases five times due to a drop in the density of solar radiation);
  • region of residence;
  • type of solar panels (multi-layer modules are more productive than single-layer ones).

The location, time of year and duration of solar radiation determine how much electricity the panel will generate during the day. Strong heating of the panel in hot weather causes a significant drop in voltage and power. Highest power solar panels can be obtained, taking into account all of the above factors that affect their productivity.

Conserving Energy with Better Solar Panel Efficiency

Solar modules are made up of photovoltaic cells connected together. They can be combined and connected in photovoltaic systems of different sizes and capacities. In addition to panels, the elements of a solar energy system are mounting structures, tracking systems (tracking the sun), batteries, an inverter, a controller and equipment for connecting to the network. The amount of electricity generated depends on the power and performance of the panel. The power of the modules depends on the intensity of the solar charge, the technologies used, the material of the photocells, and the performance depends on the quality of the panels and their technical characteristics.

How to improve the efficiency of using solar energy by solar power plants? Today there are several such methods:

  1. Use of modules with double-sided work surfaces. This contributes to an increase in electricity production by 20%. Such modules are transparent to the infrared part of the solar spectrum, which leads to a decrease in their temperature and an increase in performance.
  2. The use of high-voltage solar batteries with a voltage of 10–20 V/cm2 of the working surface, which makes it possible to reduce losses during uneven illumination of solar batteries.
  3. Use of solar modules with solar radiation concentrators.
  4. Application of vertically oriented double-sided solar modules. This increases energy production by reducing dust and snow intrusion on vertically oriented panels, reducing installation and maintenance costs.
  5. Use of sealing technology for solar modules using silicone gels. This technology doubles their service life (from 20–25 years to 40–50 years).
  6. Installation and use of modern solar tracking devices (tracking) increases the utilization of the installed capacity of modules and the production of electrical energy by 20-25%.

The output power of solar modules is constantly changing due to the changing position of the sun in the sky during the day and year. The angle of inclination of the panels is an important indicator of their efficiency depending on regional location and time of year. It is advisable to use accurate calculations to adjust the position of the modules at least 1-2 times per season.

The highest power solar panels have photovoltaic tracking systems linked to the control center of the power plant. They automatically change the angle of the panels depending on the angle of incidence of sunlight on the work surface. A swivel tracker mounted on a pole rotates the panels 360° while simultaneously changing the angle and direction relative to the sun.

You will not be able to get higher performance than that indicated in the solar battery passport by the manufacturer. It depends on the quality of the panel materials and the technical characteristics embedded in them. Modern battery models consist of different multilayer materials and absorb not only ultraviolet, but also infrared radiation.

The service life of solar panels with their proper use is quite long – from 25 to 40 years. The loss of efficiency over time can be associated with either a decrease in plant productivity or an increase in energy consumption. In these cases, its power can be increased by combining old and new parts, if they are compatible.