The voltage technology of photovoltaic power generation systems is mainly divided into several different voltage levels, and the selection of these voltage levels usually depends on the scale of the system, geographical location, and requirements for grid access.
Here are several common voltage levels and their development trends:
Common voltage levels
1. Low voltage grid connection (220V/380V)
Suitable for small distributed photovoltaic systems, such as rooftop installed photovoltaic systems in residential buildings or small businesses. This type of system typically has lower power and an installed capacity generally not exceeding 400kW.
2. Medium voltage grid connection (10kV)
When the installed capacity of photovoltaic power generation is greater than 400kW, 10kV voltage is usually selected to be connected to the grid. This system requires the installation of a step-up transformer to match the grid voltage.
3. High voltage grid connection (such as 35kV, 110kV, etc.)
Large scale ground photovoltaic power stations usually use higher voltage levels to connect to the grid, which reduces transmission losses and is suitable for long-distance transmission.
4. Increase the DC side voltage to 1500V:
This is currently one of the more advanced voltage levels for photovoltaic systems. By increasing the DC voltage from the traditional 1000V to 1500V, cable losses can be reduced, component string length can be increased, and system costs can be lowered.
5. Increase the AC voltage to 1000V:
Increasing the AC voltage also helps to reduce transmission losses, especially in long-distance power transmission. In addition, it also allows for the use of fewer inverters and transformers, simplifying system design and reducing costs.
6. High boost converter technology:
High boost converters are used to increase voltage output without significantly increasing current, which is crucial for optimizing the efficiency of distributed generation systems. For example, the boost structure of the coupling circuit has added a new gain adjustment unit, which enables the photovoltaic system to stably output higher DC voltage.
7. Multi level inverter design:
The multi-stage inverter design adopts multiple power conversion stages to achieve higher voltage gain while reducing the pressure on individual components. For example, a three-level BOOST converter not only increases voltage gain, but also reduces conduction, switching losses, and reverse recovery losses.
Development trend
The development trend of voltage technology in photovoltaic power generation systems is mainly reflected in the following aspects:
The system voltage continues to increase
The DC side voltage of photovoltaic power generation systems has gradually increased from the early 600V to 1000V, and now to 1500V, and will further develop towards higher voltages in the future. For example, Huawei predicts that by 2030, the DC side voltage of photovoltaic systems will exceed 1500V, and even reach 2000V. The main purpose of this trend is to improve power generation efficiency and reduce system cost per kilowatt hour (LCOE) by reducing line losses, equipment quantity, and material costs.
Coexistence of high voltage and high reliability
With the increase of voltage, the system has higher requirements for reliability. For example, although the 1500V system has significant advantages in reducing costs and improving efficiency, it also brings problems such as electric shock hazards, fire hazards, and PID (potential induced decay) risks. Therefore, future development requires strengthening the safety and stability of the system while promoting high voltage For example, adopting a bipolar high-voltage architecture and system level safety protection capabilities.
Technological innovation drives voltage increase
Technological progress is an important driving force for voltage increase.
For example, the application of third-generation semiconductor materials such as silicon carbide and gallium nitride, as well as the development of chip heat dissipation and topology architecture technology, have significantly improved the power density and efficiency of inverters, thereby supporting the realization of higher voltages. In addition, the application of modular design and digital technology also provides guarantees for the stable operation of high-voltage systems.
Integration and Application of Energy Storage Systems
With the development of energy storage technology, the integration of photovoltaic systems and energy storage equipment has become a trend.
For example, the 1500V DC voltage configuration has gradually become the main choice for energy storage systems, which not only reduces system costs but also improves the volumetric power density and operational efficiency of equipment. In the future, with the further maturity of energy storage technology, the voltage of photovoltaic systems may be further increased to 2000V.
Intelligent and energy-efficient design
Intelligence is an important development direction for future photovoltaic systems. By integrating intelligent components such as sensors and controllers, photovoltaic systems can monitor operating status in real time, diagnose faults, and automatically adjust operating parameters, thereby improving the reliability and operational efficiency of the system. At the same time, the design concept of high efficiency and energy conservation will also be integrated into the research and development of key equipment such as transformers and inverters.
Balance between safety and economy
Although high-voltage systems have significant advantages in reducing costs and improving efficiency, their safety issues still need to be addressed. For example, high voltage systems increase PID risk and exacerbate series mismatch issues. Therefore, future technological development requires strengthening system safety protection measures and improving technical standards while increasing voltage.
