As a new solution to effectively solve the problem of distributed photovoltaic consumption, energy storage in the station area has quickly become popular in the market.
Recently, the Shaanxi Provincial Large-scale Distribution Station Area Distributed Energy Storage Project designed by China Energy Construction Shaanxi Institute was completed and put into operation, which is the largest distributed energy storage project in China, covering 130 villages in 7 districts and counties, nearly 8,000 square kilometers, supporting 149 sets of energy storage equipment in the distribution area, with a total capacity of 29,986 kWh, committed to solving the problem of voltage overrun and distributed photovoltaic absorption, and improving the flexible adjustment capacity of the distribution station area and the flexibility of distribution network operation.
Benefiting from policy support, distributed photovoltaic in mainland China has developed rapidly in recent years, becoming the main force in the new installed capacity of photovoltaics. However, since the second half of 2023, there has been news of the filing of distributed photovoltaic projects and the suspension of grid connection in many places, mainly due to the lack of carrying capacity of access to the power grid, which brings uncertainty to the fast-growing industry. In this context, as a new solution to effectively solve the problem of distributed photovoltaic consumption, energy storage in Taiwan area has quickly become popular in the market.
Demand is rising rapidly
According to data from the National Energy Administration, in the first quarter of this year, 45.74 million kilowatts of new photovoltaic were connected to the grid across the country, a year-on-year increase of 36%, including 21.93 million kilowatts of centralized photovoltaic and 23.8 million kilowatts of distributed photovoltaic. The newly distributed installed capacity is once again overtaking the centralized.
However, the rapid growth of distributed photovoltaic installed capacity has brought about a prominent problem - the lack of consumption capacity is becoming more and more prominent. Previously, Shandong, Heilongjiang, Henan, Guangdong, Fujian and other places have successively released the assessment of the carrying capacity of distributed photovoltaic grid, showing that a large number of areas have insufficient power grid capacity. According to incomplete statistics, more than 150 counties and cities have a grid-connected capacity of distributed photovoltaics, which is the so-called "red zone".
"A large number of distributed photovoltaic access to the distribution network has brought some safety problems, such as user overvoltage affecting the safety of power supply, reverse heavy overload of distribution and transformation equipment affecting the safety of system operation, and insufficient system regulation capacity resulting in limited access to new energy." Yue Fen, deputy secretary-general of Zhongguancun Energy Storage Industry Technology Alliance, told the reporter of China Energy News that one way to solve the problem of distributed photovoltaic grid connection is to transform the distribution network, and the other way is to build energy storage in the station area.
In the distribution system, the power supply area covered by a single transformer is the station area, and the energy storage in the station area is a distributed energy storage, which is installed in the distribution station area, which can be used for dynamic expansion, load fluctuation and smooth the output of new energy power generation in the station area.
Energy storage in Taiwan area is mainly used in rural areas, and some mountainous villages are scattered in load, far away from the backbone power supply network, and the annual load peak and valley difference is significant, such as the surge of electricity load during the busy agricultural season and the Spring Festival, if the voltage loss is reduced by expanding the transformer capacity, adding a distribution station area or updating the distribution wire, the cost is high, and there are also problems of excess power supply capacity and power waste. The addition of energy storage equipment in the station area can provide additional power supply capacity during the peak power demand, ensure the stable power supply of the station area, and create conditions for large-scale grid connection of new energy.
Shandong is a major province in mainland China in terms of distributed photovoltaic installed capacity. In November 2023, Shandong took the lead in the trial and put into operation the country's first distributed photovoltaic supporting energy storage project in Dezhou City. At present, Dezhou in Shandong, Nanning in Guangxi, Jinhua in Zhejiang and other regions have issued policies to force or encourage the distribution and storage of distributed photovoltaic projects, with a distribution and storage scale of 10%-20% and a duration of 2 hours. In February this year, the National Development and Reform Commission and the National Energy Administration issued the "Guiding Opinions on the High-quality Development of Distribution Networks under the New Situation", which proposed that by 2025, it will have about 500 million kilowatts of distributed new energy access capacity. This means that in the past two years, the mainland distributed photovoltaic will maintain a rapid growth trend, if the configuration of energy storage, the scale is huge. Yue Fen believes that with the large-scale development of distributed photovoltaics, the future development space of energy storage in the Taiwan area is broad.
The cost accounts are yet to be settled
Although energy storage plays a role on the grid side, it is not the same as grid side energy storage. Yue Fen introduced that grid-side energy storage is usually large-scale, can accept the unified dispatch of power dispatching agencies, and plays a systematic and global role in peak regulation, frequency regulation, congestion alleviation, voltage support and reactive power control, and emergency backup of power system operation. The energy storage in the station area is mainly distributed in the local distribution network below 35KV. From the perspective of access location, energy storage in the station area can be regarded as a kind of energy storage on the grid side. From the perspective of the role played, limited by factors such as market mechanism, installed capacity, access voltage level, etc., the energy storage in the station area does not have the conditions to play the function of grid-side energy storage in the conventional sense.
"In fact, distributed distribution and storage has been controversial for a long time, and if there is open capacity in the local area, distributed photovoltaic projects will not be equipped with energy storage; If there is no open capacity in the local area, the local PV project is forced to use energy storage. It is important to know that energy storage itself does not generate economic benefits, and distribution and storage will undoubtedly increase the investment cost of the project and prolong the return on investment cycle. Industry experts pointed out that the construction of energy storage in the station area has become a pass for distributed photovoltaic investment and construction to a certain extent.
For a long time, there is a certain information gap between photovoltaic enterprises and end users, and the dealer model builds a bridge between enterprises and users, and the salesman finds the right site resources and introduces the order for the successful installation of photovoltaic panels, and will obtain a certain intermediary operation fee, which can also be understood as an introduction fee or resource information fee. In the current situation that distributed photovoltaic access capacity is becoming more and more scarce, the intermediary business fee of terminal salesmen has risen.
Dong Dahai, deputy general manager of the national channel center of Guangying New Energy and general manager of Shandong Province, admitted to the reporter of China Energy News that the intermediary business cost of a photovoltaic panel in the Shandong photovoltaic market has been as high as five or six hundred yuan, and the price of a five-piece household photovoltaic set (module, inverter, bracket, cable, grid-connected box) is now about 1.7 yuan/W, which is converted, of which the business fee accounts for nearly 1 yuan/W. The Shandong Dezhou project expands the amount of photovoltaic installation through the distribution and storage of the Taiwan area, which can greatly reduce the business cost of household photovoltaic intermediaries and return to the level of 50-80 yuan. "In fact, in a different way of thinking, in the entire EPC price, the original cost to the business terminal was diverted to the construction of energy storage, and the owner's investment income has not changed."
Yue Fen further pointed out that the main problem in the large-scale promotion of energy storage in Taiwan is that the revenue model is uncertain, there is no clear source of income, and third-party investors have no enthusiasm for investment.
Multi-party collaboration to solve problems
In view of the above situation, Yue Fen pointed out that energy storage in the Taiwan area is more suitable for power grid companies, on the one hand, because the power grid has load data and understands where the actual demand is; On the other hand, the power grid company can decide whether to build energy storage in the station area to replace or delay the investment in distribution facilities through economic comparison, which is more time-efficient and economical.
The above-mentioned industry experts pointed out that the problem of distributed photovoltaic consumption cannot be solved by only one way of distribution and storage. In addition to distribution and storage, power grid expansion and transformation, by adjusting the dispatching mode, promoting distributed photovoltaic to participate in the electricity spot market, and adjusting the load-side demand with a price mechanism are also effective means to solve the problem of consumption.
"Energy storage in the station area is not the only and preferred way to solve the problem of distributed photovoltaic grid connection, even if it is done, it needs to be clarified the allocation method and proportion, and the policy measures will be implemented in detail." Shi Jingli, a researcher at the Energy Research Institute of the China Macroeconomic Research Institute, pointed out to the China Energy News reporter that it is necessary to do a good job in the overall planning of photovoltaic development and grid-connected capacity, increase the transformation of the distribution network, improve the access capacity of distributed photovoltaic on the low-voltage side, and strive to solve the problem of power grid capacity. In areas where the proportion of photovoltaics has reached a certain proportion, the centralized convergence mode will be promoted to increase the capacity of stations and lines.
The centralized confluence mode is to concentrate the confluence of distributed photovoltaic projects in an area to one or several dedicated step-up transformers, which are connected to the grid through a 10 kV line. Dong Dahai said that the centralized confluence solves the problem of insufficient transformer capacity in the station area, while the distribution and storage in the station area solves the problem of excess power and insufficient consumption of the line, and the two should be coordinated and matched.
"The distribution and storage of the Taiwan area is not a panacea." Yue Fen suggested that in order to achieve high-penetration distributed photovoltaic access, it is feasible to strengthen the construction and transformation of distribution networks, improve the electricity price mechanism, and promote distributed photovoltaic to participate in the market. The cost-effectiveness of various measures varies, and in practice they should be considered on a case-by-case basis. On the whole, it is a relatively reasonable path choice to accelerate the promotion of market-oriented construction, improve the enthusiasm of market players, and realize the increase in the adjustment cost brought about by the power grid, distributed photovoltaic owners and users through market-oriented methods.
Text丨Reporter Lu Qixiu