Interview with Academician Ling Wen|When photovoltaic meets architecture, what changes will it bring?

Climate change is one of the biggest challenges facing the world today, global warming and extreme weather events have a profound impact on our lives, and finding new sustainable energy solutions is an important means for us to combat climate change.

Photovoltaic power generation is a technology that we are familiar with renewable energy, and building photovoltaic integration is to combine the photovoltaic system with the building structure to make it a part of the building. This technology can effectively use solar energy, improve the energy efficiency of buildings, and reduce carbon emissions, which is one of the important technologies in the distributed energy system. Building photovoltaic integration has broad application prospects and will also be closely related to our daily life.

In order to better understand the practical progress and future prospects of building photovoltaic integration, our reporter interviewed Ling Wen, academician of the Chinese Academy of Engineering.

China Environment News: Could you please talk about the idea of building photovoltaic integration?

Ling Wen:Building photovoltaic integration is a good green and low-carbon idea that has only been explored on a large scale in the past decade. To put it simply, 20 years ago, we started putting photovoltaic modules for ground-mounted power stations on the roofs of buildings. Later, it was improved and turned into solar photovoltaic panels hanging on the roof of the building. But it's actually still two skins, the building is the building, and the photovoltaic is the photovoltaic.

Now what we want to do is to combine two things into one, that is to say, photovoltaic panels are building materials, and building materials are photovoltaic panels. This requires a lot of work, such as for photovoltaic panels, it is necessary to consider its dustproof, less efficiency attenuation, wind and sand resistance, etc. However, for buildings, such as building curtain walls, it is necessary to consider its seismic resistance, strength, load, windproof, waterproof, and working life, so the indicators are different, but we have to make photovoltaic building integration, and the needs of both sides must be met.

China Environment News: What is the significance of building photovoltaic integration in carbon reduction?

Ling Wen:China's urban areas account for about 80% of total carbon dioxide emissions, and buildings account for more than 50%. Building photovoltaic integration can reduce carbon emissions in the operation stage of buildings by more than 30%.

At present, the new energy carrying capacity of China's regional power grid is insufficient, and the new energy grid is saturated in many places. Due to the lack of "grid connection and consumption capacity" of the distribution network, Hubei, Guangdong, Henan and other provinces have successively issued a "low-voltage distribution network connection network early warning level of red counties (cities, districts), from the date of announcement to suspend the distribution of photovoltaic power generation project filing" of the document, seriously affecting the promotion of new energy. The integration of building photovoltaics, the nearby consumption of power generation, and the further formation of an integrated system of photovoltaic storage and charging, can play the function of local regulation, which is of great significance to improve the proportion of regional new energy.

China Environment News: What is the connotation of building photovoltaic integration?

Ling Wen:Building photovoltaic integration is a high-performance and diversified photovoltaic building materials technology and products. It is not only a multi-energy technology integration architecture, but also a multi-energy system microgrid architecture and a multi-energy complementary management and control platform.

The first is the integration of photovoltaic and building systems. The building has high requirements for architectural shape, architectural color and architectural culture, so it is not possible to put the photovoltaic panels on the five major and three rough ground, and it must have good performance. At the same time, it can generate electricity, burn, durability and weather resistance, and meet the requirements of both buildings and photovoltaics.

The second is the comprehensive utilization of photoelectric and solar thermal. Photovoltaic building materials will generate a large amount of waste heat at the same time, the surface temperature can reach 70 °C, through the breathing photovoltaic wall technology, combined with fresh air units, heat pump units, to achieve the effective use of photovoltaic thermal energy, building energy saving of more than 10%.

The third is the integration of building smart energy management and carbon cloud platform technology. There is a very famous software called BIM (Building Information Modeling) for architecture. We now add a carbon function to it, put the carbon footprint and carbon emissions of the whole life cycle into it, and further combine it with the energy management system to form a building smart energy carbon cloud platform technology.

Fourth, the collaborative system of building energy, the integration of building photovoltaic and energy consumption systems, energy storage systems, and charging pile systems to achieve an "urban energy microgrid system", which can not only completely change the city's energy structure, but also increase the "resilience of the public power grid" and ensure energy security and national security (peacetime and wartime combination).

China Environment News: At present, where has the integration of building photovoltaics been practiced? The result?

Ling Wen:In 2018, my academician workstation was set up in Shenyang Jianzhu University, which is doing building photovoltaic integration, and I have done a lot of work and made a series of achievements over the years. At present, more than 100 projects have been completed.

Tonghu Science and Technology Town, Zhongkai High-tech Development Zone, Huizhou City, Guangdong Province, is one of the projects we have participated in. Tonghu Science and Technology Town is China's first copper indium gallium selenide - building photovoltaic integration demonstration building, the completion of the project, marking the Tonghu Science and Technology Town building to achieve the independent supply of green electricity, into the era of "self-power generation". The installed capacity of the project is 198.6kW, with an annual power generation capacity of 123,000 kWh and a reduction of 97 tons of CO2 emissions. Based on the 25-year life of photovoltaic panels, it can reduce 2,425 tons of CO2 emissions.

In 2015, we participated in the GROSSPETER building project in Basel, Switzerland, which is a typical office building, except for the windows, all of which are integrated with building photovoltaics, and we have given green building certification. All the tenants in the building are listed companies, and it is interesting to note that the rent of this green office building is more than 10% higher than the rent of the surrounding buildings of the same quality, and they are rushing to rent it.

Why is that? There are three main reasons for our analysis: first, carbon accounting and carbon certification can get corresponding returns, and they can win carbon trading, carbon evaluation, and carbon ranking in the future; Second, more than 1/3 of the electricity in the office building is generated by itself; The third is to make the employees of the enterprise from the original energy consumers to energy producers and consumer complexes. This is a reversal of the idea that each of us is producing energy as much as we can, and that's a good thing.

China Environment News: You just mentioned that the life span of photovoltaic panels is 25 years, so after the life expectancy is up, will the dismantled old photovoltaic panels be disposed of or recycled, will it cause secondary pollution to the environment?

Ling Wen:Photovoltaic panels have always been able to generate electricity, and the 25-year life refers to the attenuation of the efficiency of photovoltaic modules by no more than 10% in the tenth year, and the attenuation in 25 years not more than 20%, which does not mean that it must be removed in 25 years. Of course, according to the specific performance situation, it is necessary to determine whether it is to be stopped or whether it is to be removed. Because the specification stipulates that the life of the building glass curtain wall is also 25 years, and the current photovoltaic can achieve the same life as the curtain wall building materials.

The secondary pollution caused by recycling is a problem faced by all building materials, and building photovoltaic integration is no exception. At present, photovoltaic glass, silicon wafers, etc. have relatively mature recycling and reuse technologies, which is also the content we need to study in the future, and we must solve the environmental problems brought by this link of recycling.

China Environment News: What suggestions do you have for the development of a new energy system for building photovoltaic integration?

Ling Wen:The sustainable development of China's new energy technology and industry still needs the joint efforts of everyone.

First of all, the standard system is the guarantee for the sustainable development of the industry. At the government level, improve the incentive mechanism for enterprises, scientific research institutions and universities, continue to improve the development plan of the renewable energy industry, and build and improve the renewable energy standard system; At the industry level, we will give full play to the platform and guiding role of industry associations, and integrate across borders in the fields of energy, transportation, manufacturing, and construction; At the level of universities and scientific research institutes, introduce and train high-end talents, carry out relevant laboratory construction, and master core technologies; At the enterprise level, we will deeply lay out the whole upstream and downstream chain of the industry, jointly promote breakthroughs in key technologies, and vigorously promote the sound construction of the industry.

Second, we should do a good job in top-level design, introduce relevant policies, and improve the support system for power grid security and resilience. Introduce relevant policies to reasonably allocate the "distributed new energy microgrid system" with security, support and flexibility in the power grid at all levels, find a reasonable balance between concentration and distribution, and improve the extreme survival and renewable operation capacity of the power grid at all levels; Through reasonable power system planning, we will actively promote the "building photovoltaic integration" new energy microgrid system solution, and when building distributed photovoltaic power stations, energy storage power stations, and charging stations, the distribution capacity will be planned according to the off-grid operation capacity, and the access services of supporting power grids will be done well, so as to achieve a balance between the carrying capacity of distributed energy production, energy storage and energy consumption.