微型逆变器是组件级控制观念的呈现

逆变器是光伏发电系统的心脏。不仅承担将太阳能光伏产生的直流电转换为交流电的重要角色，在完成最大功率点跟踪后还要将电能并入电网或用于家用电器。作为分布式电源与电网的接口，逆变器性能将直接影响到光伏发电系统的发电效率及运行稳定性。

逆变器主要分为集中式逆变器、组串式逆变器和微型逆变器。工作原理方面，集中式逆变器是将大量并行的光伏组串连接到同一台集中式逆变器的直流输入端，完成最大功率点跟踪后，再统一并网。组串式逆变器对数串光伏组件单独进行最大功率追踪，在经过逆变单元后并入交流电网。微型逆变器则是每个逆变器只对应少数光伏组件，实现对每块光伏组件单独的最大功率点跟踪，在逆变转化之后单独并入交流电网。

微型逆变器运行效率更高、安全性更好   主要应用于户用发电场景

微型逆变器作为组件级电力电子设备可以对每块光伏组件的输出功率进行精细化调节及监控，在遇到部分阴影遮挡和个别组件性能出现故障的情况下，能够提升光伏系统整体的运行效率。同时比起集中式、组串式逆变器输入端的1000V直流高压，微型的最大输入电压仅为 60V，很大程度上降低了电站的安全隐患，在安装和调试方面也更为简单。不过相比集中式逆变器和组串式逆变器，微逆的单瓦价格较高，当下的应用场景主要以户用光伏电站为主。

一、 需求端：三重渗透下的百亿市场

作为清洁能源的太阳能在电力装机结构中的渗透率正在提升。其主要原因在于（1）加快以光伏为代表的新能源建设已经日益成为全球主要经济体的政策共识；（ 2）近年来全球通胀导致的大宗商品价格高企使得太阳能作为一种能源具备了相当的经济性。因此我们推断光伏在未来将进一步提升其在全球电力结构中的占比。

1 、 组件价格高企   分布式渐成光伏装机主力

在全球光伏装机需求持续高增下，产业链上游原材料多晶硅料价格出现了剧烈的上涨，从而带动组件价格出现了飙升。以 2021年1 月6日为基点，截至 2022年8 月10日，多晶硅料涨幅超过了 260.2%，  166/182/210  组件涨幅分别为17.7% 、 15.9%、 15.9% 。高价组件降低了集中式光伏项目的收益率。以一个100MW ，组件成本为 1.95元 /W ，项目初始投资成本为4.58 元 /W 的集中式光伏电站项目为例。根据开源证券测算，在年利用小时数为 1300h ，上网电价为0.37 元 /kWh 的情况下，项目收益率仅为 6.4% 。高昂的组件价格对当前集中式电站业主的装机意愿产生了较大的影响。

2 、 对组件价格敏感性更低   分布式电站渐成光伏装机主力

通过对比地面光伏电站和分布式屋顶光伏电站的投资成本可以看出，相比地面电站，分布式电站当中非组件成本更低，初始投资成本相比地面电站也更加低廉，这使得分布式电站对于组件价格的敏感性相对更低，对高价组件的接受度更高。

2021年全球分布式光伏占比已达 47.9%，其中户用光伏占比26%，份额连续 5年提升。高昂的组件价格直接降低了下游业主的装机意愿，而相对初始投资成本更低的分布式光伏的装机渗透率正在提升，其中尤以户用光伏装机为甚。

从2020到 2022上半年，中国的分布式光伏装机占比已经从32.2%提升到了65.5%，其中户用光伏装机占比更是从  2016 年的 1.7%提升到了 2021年的  39.4%。同时，在全球范围内的分布式光伏装机占比也实现了大幅提升。从逆变器出货统计口径看，全球分布式光伏装机占比从 2020 年的  38.9%上升到了  2021 年的 47.9%，其中户用光伏装机占比更是连续 5年实现提升，到  2021 年已经达到了26%。

3 、 兼具高效与安全性的微型逆变器是户用光伏的最优选

组串式发电系统存在短板效应会大幅下降发电功率。短板效应即木桶效应，指一只水桶能盛多少水取决于木桶最短的那块木板，光伏系统中的木桶效应则是指系统输出的电流往往取决于系统中电流最小的那块组件。在电站实际应用中，阴影遮挡、云雾变化、污垢积累、组件温度不一致等内外部不理想条件，都会造成组件内部各光伏单元输出功率不一致，进而导致各组输出功率不一致，从而导致整个系统组件失配，整个系统的发电功率都随之下降。

微型逆变器能克服短板效应，最小化个别组件的影响。微逆多路独立的 MPPT输入设计，可将每块组件的输出优化在最大功率点附近，系统发电量是所有组件发电量总和。此外，微逆启动功率更低，决定了其工作时间更长，从质和量两方面贡献更高的发电效率。

微逆的主要优势

微逆可以最小化遮挡物的影响，稳定系统输出。

微型逆变器生命周期更长，省去二次安装成本。

组件级监控，提高运维效率，节约故障维修成本。

基于高转换效率和低运维成本，微型逆变器的LCOE（度电成本）至少可降低 10%。

Micro inverter is the presentation of component - level control concept

Inverter is the heart of photovoltaic power system. It not only plays an important role in converting direct current generated by solar PV to alternating current, but also integrates the energy into the grid or uses it in household appliances after completing the maximum power point tracking. As the interface between distributed power supply and power grid, the performance of inverter will directly affect the power generation efficiency and operation stability of photovoltaic power generation system.

Inverters are mainly divided into centralized inverters, group series inverters and micro inverters. In terms of working principle, the centralized inverter connects a large number of parallel photovoltaic groups to the DC input terminal of the same centralized inverter, completes the maximum power point tracking, and then unified grid connection. The cluster series inverter is used to track the maximum power of the logarithmic series of photovoltaic modules separately, and is incorporated into the AC grid after passing through the inverter unit. The micro inverter is that each inverter corresponds to only a few photovoltaic modules, which can track the maximum power point of each photovoltaic module separately, and be incorporated into the AC grid separately after the inverter transformation.

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Micro inverters have higher operating efficiency and better security. They are mainly applied to household power generation scenarios

As a component-level power electronic equipment, the micro inverter can finely regulate and monitor the output power of each PV module. In the case of partial shadow occlusion and performance failure of individual modules, it can improve the overall operating efficiency of the PV system. At the same time, compared with the 1000V DC high voltage at the input of the centralized and group series inverters, the maximum input voltage of the micro is only 60V, which greatly reduces the potential safety risks of the power plant and is simpler in installation and commissioning. However, compared with centralized inverter and cluster inverter, the single watt price of micro inverse is higher, and the current application scenario is mainly household photovoltaic power station.

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I. Demand side: 10 billion market under triple penetration

As a clean energy, the penetration of solar energy in the installed power structure is increasing. The main reasons are as follows: (1) accelerating the construction of new energy represented by photovoltaic has increasingly become the policy consensus of the world's major economies; (2) High commodity prices caused by global inflation in recent years have made solar energy quite economical as a source of energy. Therefore, we infer that PV will further increase its share in the global power structure in the future.

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1. The distributed component with high price has gradually become the main force of photovoltaic installation

In the global demand for photovoltaic installations continues to increase, the price of polysilicon, the raw material in the upstream of the industrial chain, has risen sharply, which leads to a surge in the price of components. Based on January 6, 2021 as a basis point, as of August 10, 2022, polysilicon materials increased by more than 260.2%, 166/182/210 components increased by 17.7%, 15.9%, 15.9%, respectively. High-priced modules reduce the yield of centralized PV projects. Take a 100MW centralized photovoltaic power station project with module cost of 1.95 yuan /W and initial project investment cost of 4.58 yuan /W as an example. According to the open source securities calculation, in the annual utilization hours of 1300h, the on-grid price is 0.37 yuan /kWh, the project yield is only 6.4%. The high component price has a great influence on the installation intention of the current centralized power station owners.

2. Distributed power stations with lower sensitivity to module prices have gradually become the main force of photovoltaic installation

By comparing the photovoltaic power station on the ground and distributed rooftop photovoltaic power plant investment cost as you can see, compared with the ground station, the components of the distributed power station cost is lower, the initial investment cost is also cheaper than the ground power station, which makes the sensitivity of the distributed power station for a component prices are relatively low, willingness to accept high component is higher.

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In 2021, the global distributed PV accounted for 47.9%, among which household PV accounted for 26%, and its share increased for five consecutive years. The high module price directly reduces the downstream owners' willingness to install, while the installed penetration rate of distributed PV with lower initial investment cost is increasing, especially for household PV.

From 2020 to the first half of 2022, the proportion of distributed PV installed in China has increased from 32.2% to 65.5%, and the proportion of household PV installed has increased from 1.7% in 2016 to 39.4% in 2021. At the same time, the proportion of distributed photovoltaic installed worldwide has also achieved a significant increase. From the perspective of inverter shipment statistics, the proportion of global distributed photovoltaic installed capacity increased from 38.9% in 2020 to 47.9% in 2021, among which the proportion of household photovoltaic installed capacity increased for 5 consecutive years and reached 26% in 2021.

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3. The micro inverter with high efficiency and safety is the best choice for household PV

The short - board effect of cluster - series power generation system will greatly reduce the power generation. The short board effect is the barrel effect, which means that how much water a bucket can hold depends on the board with the shortest barrel. The barrel effect in a photovoltaic system means that the current output of the system often depends on the component with the smallest current. In power station actual applications, cloud shadows shade, change does not agree, dirt accumulation, components, temperature and other internal and external not ideal conditions, can cause the component within the photovoltaic cell power output, resulting in each output power, which leads to the whole system component mismatch, with the decrease of the power of the whole system.

The micro inverter can overcome the short board effect and minimize the influence of individual components. Microinverse multi-channel independent MPPT input design can optimize the output of each component near the maximum power point, and the system energy generation is the sum of the energy generation of all components. In addition, the micro-inverse start-up power is lower, which determines its longer working time and contributes higher generation efficiency in terms of both quality and quantity.

The main advantages of microinverse

Microinverse can minimize the influence of occlusions and stabilize the system output.

Micro inverter life cycle is longer, save the cost of secondary installation.

Component level monitoring, improve the efficiency of operation and maintenance, save the cost of fault maintenance.

Based on high conversion efficiency and low O&M cost, the LCOE (cost per kilowatt-hour) of micro inverters can be reduced by at least 10%.