The different coupling methods of photovoltaic and energy storage systems are divided into the D.C. coupling system and the A.C. coupling system, respectively, suitable for the total market of newly installed photovoltaic systems and the stock market of installed photovoltaic systems. The larger incremental market space is the main driving force for future market growth:
(1) Incremental market (newly installed photovoltaic + energy storage systems in target households): DC-coupled products are generally used. The DC-coupled energy storage system includes a battery system and a hybrid inverter, which combines the functions of a photovoltaic grid-connected inverter and an energy storage converter. The advantage of D.C. coupling is that both photovoltaic and energy storage batteries are converted through hybrid inverters, and there is no need to install additional photovoltaic grid-connected inverters. The system integration is higher, installation and after-sales service are more convenient, and it is convenient for intelligent monitoring and control. Some households that have already installed photovoltaic systems choose to remove the original photovoltaic grid-connected inverter and install a new hybrid inverter.
(2) In the stock market (target households have installed photovoltaics and newly added energy storage systems), AC-coupled products are generally used. It is only necessary to install batteries and energy storage converters without affecting the original photovoltaic system. In principle, the design of the energy storage system is not directly related to the photovoltaic system and can be determined according to needs. The advantage of A.C. coupling is high safety: in A.C. coupling mode, energy is collected at the A.C. side, which can be directly supplied to the load or sent to the power grid or can be directly charged to the battery through the bidirectional converter, and low-voltage P.V. and low-voltage batteries can be selected. , eliminating the risk of D.C. high voltage in the energy storage system.
Depending on whether the system is connected to the grid, home energy storage systems can be divided into grid-connected systems and off-grid systems. The core difference is whether the system is connected to the grid. Currently, most areas use a grid-connected and off-grid integrated system. (1) Grid-connected systems, photovoltaic, and energy storage systems can be connected to the grid. Electricity can be purchased from the grid when the power of photovoltaics or batteries is insufficient. It is suitable for areas with stable power systems and relatively low electricity prices. (2) The off-grid system is suitable for areas such as deserts and islands without power grids or areas where the power grid is unstable and needs to be used by itself. Use off-grid energy storage converters, usually with a diesel generator interface, to supplement power when the battery power is insufficient at night. (3) On-grid and off-grid all-in-one machine, with on-grid and off-grid switching function or integrating grid-connected and off-grid modes in one machine, it can switch to off-grid mode during a power outage, which is suitable for unstable power systems and frequent power outages.
The core hardware equipment of the home energy storage system includes batteries and converters. According to the degree of integration of the products, there are mainly two modes: all-in-one machine and split machine. Split machines dominate the current market, but all-in-one machines are the development trend in the high-end market. : (1) Split machine, some A.C. coupling products, and D.C. coupling products adopt the split machine mode, the battery system and the inverter system are provided by the pack manufacturer and the inverter manufacturer, respectively, and then through the integrators, distributors, installers Channels reach end users. (2) All-in-one machine, the product is an all-in-one system including a battery and an inverter, usually an AC-coupled product. Upstream battery systems and inverters provide products as suppliers, usually in the OEM mode. The supplier's brand is not displayed in the final product, and the sales and after-sales of the products are all borne by the brand owner.
According to the voltage of the battery pack, it can be divided into high-voltage batteries and low-voltage batteries. The industry shows a trend of switching to the high-voltage battery. The primary purpose is to improve efficiency and simplify system design, but at the same time, it requires higher cell consistency and BMS management capabilities. High-voltage batteries usually have a battery pack voltage of more than 48V and can achieve high voltage at the battery pack level by connecting multiple cells in series. In terms of efficiency, using batteries of the same capacity, the battery current of the high-voltage energy storage system is smaller, the interference to the system is more minor, and the efficiency of the high-voltage energy storage system is higher; in terms of system design, the circuit topology of the high-voltage hybrid inverter is simpler, smaller size, lighter weight and more reliable. However, high-voltage batteries are composed of multiple cells in series and parallel. The higher the voltage, the more batteries are connected in series, and the higher the requirements for the consistency of the cells. At the same time, it needs to cooperate with an efficient BMS management system. Otherwise, it is prone to failure.
The industrial chain has three types of enterprises: 1) Integrators, which only make brands and purchase all equipment. Usually outsourced batteries and inverters, integrated products are sold under their brands, with complete sales channels and strong brand power, such as Tesla, Sonnen, etc. 2) Inverter manufacturers sell inverters separately or purchase cells with integrated batteries/all-in-one machines. Inverter manufacturers benefit from accumulating brands and channels in the photovoltaic inverter industry and can quickly expand. The core of the energy storage system lies in the inverter's control of the battery, that is, the communication between the inverter and the battery. Inverter manufacturers have an in-depth understanding of power electronics technology and have more advantages. 3) There are two modes of participation for cell manufacturers. One is to supply cells for downstream brand manufacturers, not to participate in product integration, and to have no brand exposure. For example, in Ningde Times, etc., cell manufacturers have more diverse business fields and application scenarios. Rich, on the one hand, can benefit from the rapid growth of the home storage industry, and on the other hand, it can generate synergy with other businesses; another mode is to produce battery systems for separate sales or purchase inverter modules at the same time to complete hardware integration and software design, such as BYD, Penang Technology. The business models of industry chain participants show two major trends: (1) Inverter and cell manufacturers are integrated downwards, and product integration can strengthen the control of sales channels and improve profitability; (2) Some manufacturers focus on For equipment supply, it can open up more customers and a wider range of application scenarios, and win by quantity.
1.2 Value: The investment cost of the whole system is nearly 80,000 yuan
Take a 4.68kw photovoltaic + Wotai 5.8kwh/6kw energy storage system as an example; the total investment is about 10,000 pounds, equivalent to a unit price of 17.61 yuan/w. Among them, the photovoltaic system accounts for 32%, the component is 3.08 yuan/w, and the photovoltaic inverter is 2.56 yuan/w. The energy storage system accounts for 35%, and the unit price is 4.97 yuan/wh. Other materials + installation costs £3,400, accounting for 33%.
1.3 Trend: High-capacity battery + hybrid inverter + all-in-one machine trend
From the perspective of battery trends, energy storage batteries are evolving towards higher capacity. With the increase in residential electricity consumption, the electricity charged in each household gradually increases, and some products realize system expansion through modularization. Due to the penetration of cigarettes, the increase in the power of household appliances, and the impact of a home office, the electricity consumption of each household has increased, and the demand for energy storage has increased. (1) Regarding sub-regional markets, the overall charge per household has gradually increased. Taking the German market as an example, the average charge in 2021 is 8.8kwh, while the data for the same period is 8.5kwh in 2020 and 8kwh in 2019. The increase in electricity consumption in the German market is mainly due to the development of new energy vehicles and the increase in household electricity consumption. (2) Modular battery for easy capacity expansion. The charge and power of a single product are limited, and the manufacturer will set the product to achieve flexible configuration through the modular combination to meet the needs of different capacity scenarios. (3) The battery moves from low pressure to high pressure. The higher voltage battery system generates less heat, improving system efficiency, simplifying the circuit structure, and facilitating system installation. With the improvement of cell manufacturing technology and battery management system control technology, high-voltage battery systems have become an industry trend.
In terms of inverter trends, the demand for hybrid inverters suitable for the total market and off-grid inverters that do not need to be connected to the grid increases. (1) The new P.V. distribution and storage power is sufficient, and the demand for hybrid inverters increases. Because the current home energy storage system is dominated by the incremental market (new distributed photovoltaic users supporting energy storage), the demand for hybrid inverters has increased. The stock market already has photovoltaic grid-connected inverters, so when incrementally installing the energy storage system, the energy storage inverter is selected. At the same time, the incremental market generally combines photovoltaic inverters and energy storage converters into hybrid inverters devices. Users are more inclined to install energy storage when newly installed photovoltaics, mainly because the uncertainty of the net metering policy of household photovoltaics overseas has become stronger, and the uncertainty of household photovoltaic income has increased. Reduce earnings uncertainty.
(2) Markets such as the United States and South Africa drive the demand for off-grid inverters. In the United States, natural disasters are frequent, the risk of power outages is high, and the power grid in the United States is relatively fragile and aging. In order to stabilize the power grid, some photovoltaic system power companies do not allow it to be connected to the power grid. Therefore, installing off-grid, spontaneous, and self-use is necessary to replace the generator. The U.S. market is proliferating, and the demand for off-grid energy storage converters that fit the U.S. market has increased significantly. Deye integrates grid-connected and off-grid mode designs in the same machine, and its products are popular in the U.S. market with outstanding cost control capabilities.
From the perspective of the trend of end products, the split type is currently the main one; that is, the battery and the inverter system are used together, and it will gradually develop into an all-in-one machine in the future. In the past, battery manufacturers usually provided battery systems, and inverter manufacturers provided hybrid inverters. The sales channels were based on the compatibility of batteries and inverters. Different brands of products bring tediousness to installation and after-sales. Therefore, pack manufacturers and inverter manufacturers have begun to involve each other. Some inverter manufacturers (such as Huawei, GoodWe, etc.) have purchased cells to assemble packs by themselves and integrated the batteries and inverters for sale. On the one hand, it can expand sales.
On the other hand, it can help consumers save one-time equipment investment, simplify installation, save installation costs, and facilitate after-sales maintenance. All-in-one products of battery manufacturers such as Penang are under development. The overall price of the all-in-one terminal is relatively high. Still, the all-in-one terminal has a high degree of integration, which reduces the difficulty of installation and saves installation costs. The hardware cost in overseas markets only accounts for less than half of the overall cost. The subsequent labor costs, including installation, service, design, grid connection application, and subsidy application, account for the main proportion. The all-in-one machine can save subsequent costs, so it is gradually recognized in the high-end market.
From the perspective of regional market trends, differences in a power grid structure and power market result in slight differences in mainstream products in different regions. The European grid-connected model is the primary model, the United States has more grid-connected and off-grid models, and Australia is exploring the virtual power plant model. (1) There are many grid-connected models in Europe at present. The photovoltaic penetration rate in the European market is high, the power grid is relatively stable, and the grid-connected system can meet the demand. The energy storage system needs to interact with the power grid, so the inverter of the product needs to be certified for grid connection to meet the requirements of the local power grid. In grid-connected applications, customers can switch modes. In standard power generation mode, photovoltaics meet the electrical needs during the day, then charge the battery, and automatically switch at night. With the D.C. output from the battery, the inverter switches to 220V to supply power to the load at home; photovoltaics on rainy days. When the power generation is insufficient, it sends an instruction to the power grid to purchase electricity from the power grid to meet the household load and charge the battery simultaneously.
(2) There are many off-grid models in the U.S. market. The laying of the U.S. power grid was concentrated in the last century, and the power grid facilities were relatively old, which posed hidden dangers for the power transmission capacity and load capacity of the power grid, and the problems of aging equipment and outdated technologies were prominent. According to the U.S. Department of Energy statistics, 70% of transmission lines and power transformers are over 25 years old, and 60% of circuit breakers are over 30 years old. According to the IEA, U.S. users experienced an average of 3.2 hours of outages during a major event and an average of 1.5 hours without a major event, for a total of nearly 5 hours. For areas with frequent severe weather, the average annual power outage can reach more than 10 hours. The on-grid and off-grid integrated machine can realize fast on-grid and off-grid mode switching. The battery is used as the power supply in the event of a power outage. When the battery power is not enough, the battery can only be fully charged the next day, so the on-grid and off-grid need to match diesel engines, photovoltaics or wind power. Interface.
(3) Australia is exploring the virtual power plant model. Multiple households with photovoltaic energy storage systems can accept the VPP agreement and receive grid dispatch. Households can sell excess electricity; when there is a demand for electricity, electricity is purchased through this setting and then connected to the grid. For distributed energy sources such as residential solar systems, residential and commercial energy storage systems, and V2G electric vehicles, the Australian Energy Market Operator (AEMO) has formulated new technical standards and launched a virtual power plant solution. Distributed energy can meet the needs of users. At the same time, demand participates in the electricity market to obtain benefits.
2. Marketspace: distributed photovoltaics exceed expectations + energy storage penetration rate is "double beta," and it is expected that the world will add 58GWh of installed capacity in 2025
Home energy storage is usually used in conjunction with household photovoltaics, and the installed capacity has ushered in rapid growth. In 2015, the annual newly installed capacity of global household energy storage was only about 200MW. Since 2017, the global installed capacity has increased significantly, and the growth of new installed capacity has increased significantly every year. By 2020, the global newly installed capacity will reach 1.2GW, a year-on-year increase of 30%. Europe and the United States are the markets with the most significant growth potential in the world. In terms of shipments, according to IHS Markit statistics, the global new household energy storage shipments in 2020 will be 4.44GWh, a year-on-year increase of 44.2%. Among them, Europe, the United States, Japan, and Australia are at the forefront, accounting for 4.4% of global shipments. 3/4. Among the European markets, the German market is developing the most rapidly. Germany's shipments exceeded 1.1GWh, ranking first in the world. The United States shipments also exceeded 1GWh, ranking second. Japan's shipments in 2020 will be nearly 800MWh, far exceeding other countries.
2.1 Demand-driven: The energy transition is imminent, and distributed photovoltaics exceed expectations
Excessive dependence on foreign energy has brought about an energy crisis, and the Russian-Ukrainian war has exacerbated conflicts. In the European energy structure, natural gas accounts for a high proportion, accounting for about 25%. According to the B.P. Statistical Yearbook of World Energy, in the European energy consumption structure, fossil energy accounts for a high proportion, of which the proportion of natural gas is stable at around 25%. European natural gas is highly dependent on foreign countries, mainly relying on imports. Of the natural gas sources, 80% come from imported pipelines and liquefied natural gas, of which the pipeline gas imported from Russia is 13 billion cubic feet per day, accounting for 29% of the total supply. Excessive dependence on external energy seriously affects energy security. The government hopes to reduce Rely on and maintain national security. Russia's cessation of natural gas supply to Europe will threaten the energy supply in Europe, and there is an urgent need to develop clean energy to ensure energy supply.
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