1) How do you see inverter technology evolving to 2030?
It has become a global consensus to vigorously develop clean energy in the context of carbon neutrality and global energy security. According to the renewable energy development expectation of the International Energy Agency (IEA) and the International Renewable Energy Agency (IRENA), it is estimated that the proportion of renewable energy power generation will reach 90% and the world's cumulative PV installed capacity will reach 14,000GW by 2050, compared with 970GW by the end of 2021.
As the PV power station type becomes increasingly complex, the inverter type spectrum is expected to be more diversified to meet the demands of different application scenarios. PV inverter technology is developing towards the goal of helping minimize LCOE. Both central and string inverter capacity will be continuously improved for large block sizes catering to high power and bifacial PV modules. In order to be better compatible with high power modules, the capability of higher MPPTs and the ability to operate at higher current have been improved especially on string inverters. Meanwhile, for utility-scale inverters, voltage level will be increased to 2000V or even higher to save cable cost. The adaptability of power grids has been continuously enhanced with the increasing penetration of renewable energy and multi-energy complementarity, and various protections have been improved to ensure safety and reliability as well. With adding installation of PV + ESS system, DC/AC ratio and inverter overloading capacity will be increased to a higher level. The application of various new devices and new topologies such as SiC and DSP with excellent performance promotes the improvement of the inverter efficiency, realizing higher power density and optimized overall costs.
2) How have your own inverters evolved in the past decade?
Driven by the pursuit of lowest LCOE, the technical solutions of PV power plants have changed rapidly in the past decade, such as higher voltage, higher power, large block size, etc.
As one of the global leading inverter manufacturers, Sineng is committed to innovating in inverter design and technology. Now the Company possesses a full range of inverter from 8kW to 3400kW, covering residential, C&I and utility scenarios.
Both of Sineng’s central and high power string inverters have been switched from 1000V to 1500V, with a higher capacity of 3.4MW for central inverter and 275kW for string inverter. Catering to high power PV modules, the string inverter input current per string is improved from 11A, 13A, 15A to 20A. In the meantime, the string inverter input current for C&I and residential projects have be modified with higher level input current.
Latest technologies like two-phase heat exchange ventilation to improve IP level, Power Line Communication (PLC) to save communication cable cost, Intelligent IV-curve scanning for easy O&M have been applied, which ensures to meet the demands of various application scenarios.
3) As storage becomes cheaper, how are storage plus inverters different from regular grid tied inverters?
The impact of PV power generation system on the power grid is mainly caused by the instability of power supply. From the perspective of grid safety, stability and economic operation, the PV generation system without energy storage tend to have negative effects on line power flow, system protection, power grid economic operation, power quality and operation dispatch. The impact of PV power station grid connections on the power grid can not be ignored, especially large-scale ones. At present, storage inverter is the effective solution to tackle that problem.
Large scale storage inverter is equipped with a variety of working modes, such as system peak shaving, frequency modulation, planned tracking output, smooth output control, economic operation, etc. Different regions have different requirements for energy storage, but the overall design principle of PV + ESS operation strategy aims to achieve 3 objectives: first of all, the requirements of dispatching frequency modulation or peak shaving ought to be responded, while the economic goal of optical storage power station be achieved; secondly, each working mode should set a reasonable priority according to actual needs; moreover, it should realize coordinated operation and seamless switching of multiple working modes.
With regard to residential and commercial PV + ESS, it can effectively improve the penetration and consumption capacity of renewable energy, better meeting the diversified needs of customers, achieving accurate energy supply with lower power consumption deviation and more assessment yields. The combination of energy storage and PV power stations is able to reduce customers’ dependence on power grids and make power consumption more convenient.