Let you understand photovoltaics from three aspects: radiation, pollution, and energy consumption

With the rapid rise of photovoltaics in recent years, some voices in the society have questioned it, including whether photovoltaics have radiation, whether they produce pollution, whether they consume too much energy, and so on. Although the photovoltaic industry has proved from the principle and technology that photovoltaic power generation has no negative impact on the human body, the environment and energy consumption, there are still some people who are keen to spread false news and mislead others. Nenghuanbao once received a similar message on the self-media, saying, "Photovoltaic is not environmentally friendly and pollutes!" Today we will use science to prove it!

about radiation

First of all, we need to figure out what radiation is and what kind of radiation is harmful to the human body!

In nature, any object whose temperature is higher than absolute zero can produce radiation. Therefore, almost all objects around us are producing radiation all the time, including ourselves! But not all radiation is harmful to the human body!

Radiation is divided into ionizing radiation and electromagnetic radiation. The former is a high-energy ray, such as X-rays and nuclear radiation that we are familiar with. They all belong to this type of radiation. Long-term exposure to the radiation area will damage human tissues. Compared with the former, the latter has a much lower radiation intensity, and the radiation frequency can be divided into ultraviolet, visible light, infrared, microwave, radio wave, low-frequency electromagnetic wave, etc. from high to low.

The principle of photovoltaic power generation is the photoelectric effect, which is related to photons, and photons are a type of electromagnetic wave, so electromagnetic radiation will be generated. So, as a low-frequency radiation, is photovoltaic power generation harmful to the human body?

We know that photovoltaic power generation is a technology that directly converts light energy into DC power by using the photovoltaic effect. The entire power generation system is mainly composed of three parts: photovoltaic modules, controllers and inverters. Electrical boxes, transformers, etc. Among them, the photovoltaic modules and cables are DC, which can only generate electric fields, not magnetic fields, and the radiation it produces can be ignored. The one that can really measure the radiation data is the transformer, but the frequency is very low, only 50 Hz; the other is the inverter, the frequency is 5-20 kHz, but the country has strict regulations on the electromagnetic compatibility of the inverter. standard. It can be said that the electromagnetic radiation of the inverter is about equal to that of our laptops, and even lower than that of household appliances such as refrigerators and hair dryers.

So some people say that photovoltaic power generation has radiation, no problem, because everything has radiation! But if you want to say that photovoltaic power generation is harmful to the human body, then please don’t equip your home with refrigerators, microwave ovens, TVs, computers, or even mobile phones used!

about pollution

Photovoltaic power generation generates electricity, and air pollution is nonsense. The more controversial issue here is light pollution. Light pollution refers to the situation where a certain amount of light enters the eyes, exceeds a certain range, causes discomfort to the eyes, and even causes adverse physiological reactions. Common light pollution is caused by reflections from mirrored buildings and unreasonable lighting at night.

Photovoltaic power generation does not have the problem of glowing at night, it can only be reflected in buildings. Let's first understand the photovoltaic module, which is mainly composed of cells, tempered glass, backplane, adhesive film, frame and other parts. Among them, the role of the battery sheet is to absorb visible light and convert it into electrical energy without reflecting light, and only glass is the most likely to reflect light.

The glass we see in many fields such as architecture, automobiles, and display screens needs to be coated. Among them, the glass commonly used in buildings and photovoltaic curtain walls is a kind of heat-reflecting glass, which is coated with one or more layers of metals such as chromium, titanium or stainless steel or their compounds on the surface of the glass to make the product present rich colors. Appropriate transmittance for visible light, high reflectivity for infrared rays, and high absorption rate for ultraviolet rays, also known as solar control glass. Typically, their reflection coefficients for visible light are between 9% and 11%. With the development of technology, some photovoltaic architectural glass is now made of colored and frosted surfaces to further reduce light reflection. So do PV modules reflect light? It does, but not to the extent that it creates light pollution.

About energy consumption

Photovoltaic cells are extended by relying on silicon raw materials, and silicon is a non-ferrous metal. When it comes to non-ferrous metals, "careful people" will link photovoltaics with "high energy consumption and high pollution".

In fact, photovoltaic cells do consume a certain amount of energy during the production process. Among them, the energy consumption of industrial silicon purification, high-purity polysilicon production, monocrystalline silicon rods, and polycrystalline silicon ingot production is relatively high. Consumption accounts for about 56%-72% of total energy consumption, but photovoltaic cells can continuously generate energy during a conservatively estimated 25-year lifespan. According to estimates, under the average sunshine conditions in my country, the energy return of a photovoltaic system in its entire life cycle exceeds its energy consumption by more than 15 times. It's like paying for children to go to school. If you can't enter the society and earn money later, you feel that the investment in learning skills in the early stage is a waste of money!

On the other hand, regarding "high pollution", it mainly comes from the by-products of high-purity polysilicon production. At present, the improved Siemens method is mainly used in the production of high-purity polysilicon in my country, and closed-circuit production has been achieved, and the by-product silicon tetrachloride and tail gas (hydrogen and chlorine) that may cause air pollution are recycled to achieve clean production. In December 2010, the state issued the "Polysilicon Industry Access Conditions", which stipulated that the recovery and utilization rates of silicon tetrachloride, hydrogen chloride, and hydrogen in the reduction tail gas should not be lower than 98.5%, 99%, and 99%. Therefore, the mature improved Siemens production technology can fully meet the requirements of environmental protection.

Based on the above analysis, from the point of view of nitpicking, the remarks that photovoltaic power generation has no radiation and no pollution lack rigor, but those rumors that photovoltaic radiation will harm the human body, cause damage to the environment, and consume too much energy are also true. Talking nonsense! After all, the country will not do things like throwing stones at your feet! Being able to get government support shows that photovoltaic power generation must have significant green attributes, and it is an important part of promoting the transformation of my country's energy system and helping to achieve the double carbon goal!

Here, I hope that those who don't know about photovoltaics, or those who have only a half-knowledge, don't listen to rumors and spread rumors. If you want to know more professional knowledge in the photovoltaic industry, please pay attention to the official WeChat and video accounts of Nenghuanbao, let us participate in environmental protection and help low-carbon!