Photovoltaic inverter "upgrade" trend is coming

The global photovoltaic inverter market is welcoming the first wave of replacement. Market research institutions pointed out that as the life of photovoltaic inverters in early ground-based power stations expires, the global demand for upgrading and replacing photovoltaic inverters is emerging. It is expected that the global demand for replacement of photovoltaic inverters will reach millions of kilowatts this year, of which the Asian market accounts for more than 40%, and the Chinese market accounts for a large proportion.

However, since most of the early domestic centralized photovoltaic power station inverter products were imported products, the output voltage level was different from that of domestic products, resulting in the problem of voltage level and impedance characteristic mismatch in the replacement of photovoltaic inverters in early large-scale ground power stations. In this context, how to upgrade and transform photovoltaic power stations at the lowest cost has become an important issue that the industry needs to solve.

Demand for technical transformation of existing photovoltaic inverters is rising

Founder Securities predicts that the global demand for replacement of photovoltaic inverters will be 13.2 million kilowatts this year, and will grow rapidly to 37.3 million kilowatts by 2025. And as the scale of new global installations continues to increase, the demand for replacement of photovoltaic inverters will continue to grow in the future. Photovoltaic inverter manufacturers will also usher in new major development opportunities.

Market research firm IHS Markit also released a report earlier, saying that as the life of early ground-mounted photovoltaic inverters expires or some of them fail, the first wave of photovoltaic inverter replacement has arrived. China will become the world's second largest photovoltaic inverter replacement market with a huge volume. However, due to factors such as competition in the photovoltaic inverter market and product upgrade technology, it is not easy to open up this blue ocean.

Zhang Hongliang, general manager of the new energy business department of Shandong Aotai Electric Co., Ltd. (hereinafter referred to as "Shandong Aotai"), said: "Before 2014, domestic ground power stations mostly used imported brands of photovoltaic inverter products such as Emerson, Siemens, and GE. The output voltage of photovoltaic inverters such as Emerson is 380 volts, which does not match the voltage level of 270 volts or 315 volts of the current mainstream domestic photovoltaic inverter products. If you simply replace it with domestic products, you can't guarantee the maximum power output of the photovoltaic inverter, resulting in a decrease in power generation efficiency and a direct reduction in power generation."

But it is very difficult to find the imported products in the past. Industry insiders pointed out that nowadays, domestic inverter brands have a market share of 98% in the domestic market and more than 60% in the global photovoltaic market. European and American brands that monopolized the Chinese photovoltaic inverter market have long been forced to withdraw. Take Emerson as an example. It stopped production in 2014 and no longer provides upgrade services. Once there is a problem with the photovoltaic inverter, the only option is to replace the unit module compatible with the Emerson photovoltaic inverter. This method is not only expensive, but also has problems such as poor heat dissipation and failure to meet current national standards.

Technical transformation should “spend less and do more”

In this context, the photovoltaic inverter self-boosting technology developed by Zhang Chenghui, my country's new energy grid-connected control expert and Shandong University Chair Professor, and his team provides a new solution to the above-mentioned problems.

According to reports, the self-boosting technology mainly solves the voltage matching problem when replacing photovoltaic inverters. After replacing a new photovoltaic inverter, only 15% of the total capacity of the self-boosting device is needed to meet the on-site needs, without changing the arrangement of components or spending a lot of money to find original parts.

In the eyes of industry insiders, this technology has two major advantages. One is "spending the least money to do the most". "Cost reduction and efficiency improvement" is the eternal theme of the photovoltaic industry. As an important power conversion equipment in power stations, photovoltaic inverters must also start with this major goal. After using self-boosting technology, the cost of upgrading and renovating 380-volt photovoltaic power stations is extremely low, which has the effect of "a little effort to achieve a great result".

As a school-run enterprise of Shandong University, Shandong Aotai first applied this technology to the inverter technical transformation of early centralized photovoltaic power stations, and completed a series of photovoltaic inverter technology innovations, realizing product innovation and upgrading. "Since 2014, some customers have reported to us the difficulties in photovoltaic inverter technical transformation. Either they can't find a suitable photovoltaic inverter to replace, or even if they find one after great difficulty, they can't afford the replacement fee. The self-boosting technology effectively solves this problem." Zhang Hongliang said.

"Soft instead of hard" advanced algorithms promote upgrades

The voltage matching problem has been solved, but new challenges have arisen. After adding a self-boosting device, the inverter's operating voltage range has also been expanded. To maximize the effectiveness of a photovoltaic power station, it is necessary to maximize efficiency, power generation, and revenue, and find the optimal peak of photovoltaic power generation. Based on the idea of ​​"replacing hardware with software", Zhang Chenghui proposed an automatic optimization technology to find the maximum power point from the software level to achieve the goal of increasing power generation.

In addition, in order to keep photovoltaic power in good grid synchronization and stability, Zhang Chenghui also integrated nonlinear control and power electronics to overcome the problem of precise photovoltaic grid control under grid failure and multi-source disturbance. Zhang Chenghui said: "Although photovoltaic power is clean electricity, its output power fluctuates greatly and interferes with the grid. What we need to do is to upgrade the control system, optimize the control algorithm, enhance the stability and safety of photovoltaic inverters, replace hardware with software, and develop new functions for photovoltaic inverters to improve the quality of photovoltaic power supply, so as to help the grid instead of causing trouble."

At present, the above technology developed by Zhang Chenghui and his team has been industrialized on a large scale and successfully applied in the upgrading and transformation project of 380V photovoltaic power stations. Among them, the first batch of ground power stations in China, the 50,000-kilowatt photovoltaic power station in Qinghai Huaneng Golmud, has increased its power generation by 9% after completing the localization replacement and upgrading of the inverter.