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Photovoltaic inverter six major technology trends

With the diversification of power station types, higher challenges are presented for system design: large ground power stations will still maintain a large market share; as policies continue to improve, distributed power plants such as roofs will develop rapidly; New applications such as photocomplementation and floating photovoltaics will increase. The selection of inverters should reflect the basic principle of “according to local conditions and scientific design”. The recommendations for different applications are as follows:
 
1. For large ground power stations, centralized inverters have always been the mainstream solution. Lower initial investment, more friendly grid access, and lower cost operation and maintenance are the main basis for choosing centralized inverters. The actual operation data of multiple power stations show that, in flat and unobstructed applications, the centralized and string power generation are equal; and the single inverter capacity of centralized inverters continues to increase, and systems above 1MW will gradually increase; As a complement, inverters such as the 40-100kW and more larger string inverters will gradually replace the 20-40kW string inverters.
 
2. The complementary fishery, water floating, and large roof power stations need to consider the convenience of installation and maintenance as much as possible: they should be installed as close as possible to the roadside; because the installation surface is flat, there are no different orientations, there is no partial shelter, and multiple MPPTs generate electricity. The quantity increase is not obvious, so the centralized inverter is preferred; and in the high-humidity environment, it is necessary to focus on the PID protection of the system; and the maximization of the comprehensive income of the photovoltaic system and fishery aquaculture.
 
3. The string inverter has a small capacity, a large number of MPPTs, and flexible configuration. It is mainly applied to complex small-scale hill power stations, agricultural greenhouses, and complex rooftops.
 
For the development trend of inverter products, as the type of power station becomes more and more complex, the product spectrum of inverters will be more diversified to meet the needs of different application scenarios. Specifically, it is mainly reflected in the following six aspects.
 
Trend 1: High-speed development of inverter hardware
 
The use of various new devices such as SiC, CAN, and high-performance DSPs, and the application of new topologies, has led to continuous improvements in the efficiency of inverters. At present, the maximum efficiency of inverters has reached 99%, and the next goal is 99.5%; China's efficiency has been improved. Reach A level, the next goal is A+, A++.
 
Trend 2: Centralized inverter power increases, efficiency increases, and voltage level increases
 
Inverters with higher power levels such as 2.5MW will be widely used. Compared with 1MW square arrays, 2.5MW solutions can reduce costs by about 0.1 yuan/W, that is, 100MW power plants can reduce initial investment by 10 million. In addition, after the cable is matched, the loss of the DC part is ensured.
 
It is worth mentioning that the 1500V system will be the development trend of large-scale power plants. Compared with the 1000V system, the investment of 0.2 yuan/W can be saved in addition to the components, equivalent to a savings of 20 million yuan for a 100MW power plant. At the same time, system losses can be reduced by approximately 0.27%.
 
Trend 3: The single-unit power of the string inverter keeps increasing and the power density increases
 
The power of the string inverters has been continuously increased. At present, the maximum power has been increased to 80 kW, the power density is also increasing, and the weight is continuously reduced to meet the complex application environment where installation and maintenance are difficult. Solar Power's 40kW string inverter has achieved 39kg, which is the lightest 40kW product in the industry. In respect of heat dissipation, Sungrow Power has always adhered to smart fan cooling methods to further reduce the temperature rise of internal components and increase the overload capacity of the inverter in high temperature environments. The fan protection rating used is IP65 and the lifetime can reach 70,000 hours. At the same time, the fan can provide a 20-year warranty.
 
Trend 4: Increasingly richer component-level products (MLPE)
 
Component-level products are becoming more and more abundant, such as micro-inverters represented by Enphase and power optimizers represented by SolarEdge. According to industry research agency GTM, shipments of component-level power electronics (MLPE) equipment will increase from 1.1 GW in 2013 to over 5 GW in 2017.
 
Trend 5: The adaptability of power grids continues to increase, and various types of protection are more complete, ensuring safety and reliability
 
Protection functions such as leakage current protection, SVG function, LVRT, DC component protection, insulation resistance detection and protection, PID protection, lightning protection, and PV positive and negative reverse polarity protection, and the ability of the inverter to adapt to the power grid is further enhanced and continuously improved. The protection function makes the system more secure and reliable.
 
Trend 6: The environmental adaptability of the inverter continues to increase
 
With the increasing application of photovoltaic power stations in harsh environments such as coastal areas, deserts, and highlands, the environmental resistance of anti-corrosion and anti-sanding of inverters has been continuously improved to ensure high reliability in harsh environments.
 
When talking about the development trend of photovoltaic systems, Zhao Wei stated that through the application of various new technologies and new products, the progress of photovoltaic technology will continue to be promoted, system efficiency PR will be improved, and the cost of electricity (LCOE) within the system life cycle will be reduced. Cheaper Internet access is the goal of everyone's common struggle.
 
The design of the power station will be more refined; the degree of system integration will be further improved, and the integrated solution of integrated inverters and medium voltage transformers will be able to simplify the system to the extreme, while reducing costs, facilitating use, improving efficiency, and improving reliability.
 
The development of photovoltaic inverter industry is in the ascendant, and various new technologies and products are changing with each passing day, which can be described as local conditions and contend; in large ground power stations, the initial investment of centralized solutions is lower, and the subsequent operation and maintenance costs are only 1/3. The results of a number of power plant operations show that the string and centralized power generation are equal, which is the user's first choice; 2/2.5MW solutions will become the mainstream next year; string inverters are also increasingly used in distributed applications. Many, high power, high efficiency, high power density is the future direction of development; PV + Internet for the majority of customers recognized, digital smart power station will become the mainstream; photovoltaic + energy storage applications have broad prospects.
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