How is the generating power of the double-sided module calculated?

Add Time：2020/5/7    Views：278

Whether domestic or foreign, one component manufacturer after another has announced the capacity planning of double-sided modules, and buyers have begun to consider the power generation gains brought by double-sided modules. According to independent calculations, in countries such as Germany, double-sided revenue growth of up to 15% or more is achievable. Most of the module manufacturers are already selling double-sided modules, and photovoltaic power plants using double-sided modules have also been constructed around the world. It is expected that double-sided modules will emerge in the solar market and occupy a prominent market share.

But in fact, many practitioners do not know what specific benefits they can get from these components, and how to optimize the system. After all, the "easiest, replacement component" approach is impractical.

The double-sided module can capture the light on both sides of the module, so it can generate electricity on both sides; the power generation capacity on the back is the key to the module's power generation.

Senior scientist Christian Reise has predicted the yield of double-sided batteries for many years. He believes that a gain of 5-15% is a realistic goal for large factories. At the same time, he also emphasized that the additional output is not just the contribution of the double-sided component, which mainly depends on the system design.

In order to make full use of the power generation capacity of the double-sided module, the module must be simulated in a specific environment to prove that the additional cost of the double-sided module is reasonable compared to the ordinary module. But in fact, the new components complicate these simulations: in the past, only the position of the sun and the illuminated area on the front of the component were considered, but now the installation system and the projection of the component itself and the reflection of the ground have to be considered. How does the reflectivity change during the year? Summer green grass, winter dry grass, snow, frost will increase the difficulty of simulating double-sided components.

For many manufacturers, it is still not easy to find double-sided parameters on the specification table. However, how to present double-sidedness on the specification sheet, a standardization process is currently being established. At the same time, Reise recommends that measuring components on both sides requires the establishment of independent solutions. This involves covering one side under standard conditions while testing the other side.

A simple and crude measurement method popular with manufacturers is: If a double-sided 300W module produces more than 5% of power due to illumination from behind, it is a 315-watt module. In fact, it is important to understand how much backside irradiance is needed to achieve a 5% increase in output.

The efficiency of the back of the double-sided module is worse than the efficiency of the front. In addition, the relationship between the electrical power output of the module and the light input is not completely linear. Double-sided components will be more accurate. Despite this, there is still no mention of the light absorption capacity of the back. Therefore, Reise proposed that as a standardized measurement in the future, the light from the light source is synchronously guided to both sides via the mirror. With the help of filters, the power of the back can be determined even at lower irradiance. The use of multiple filters that gradually reduce the irradiance level results in a clear power curve on the back of the module.

It is also worth noting that the positive power generation capacity of the double-sided module is actually slightly lower than that of the single-sided component with the same other parameters. This is because the single-sided white backplane can internally reflect and generate additional power of several watts.