With the increasing installed capacity of photovoltaic power stations in China, the power generation capacity and maintainability will become an important factor in the design of power plants. String string inverters have the characteristics of flexible design, convenient maintenance and strong adaptability. They can be used not only in distributed rooftop power stations but also in large-scale ground power stations.
With the continuous development of technology, the string-type inverter presents a trend of full-power segment range. 1KW-50KW, rich power segment grade and more lightweight design have become the development direction of many inverter manufacturers. . At the same time, with the continuous landing of Internet policies in all aspects, the design of string inverters has ushered in a new round of challenges. String inverters with smaller power and more home use have become a direction for future development. . However, how to stand out in many homogenized machines is the most direct and most realistic issue facing manufacturers. How to choose a suitable inverter has become the reality that many owners need to consider.
The new generation of domestic string inverters should have higher power density, integrated design, and more practical features. How to achieve these goals is the focus of this article.
The following figure shows the appearance comparison of the first generation of SS and the new generation of NS of Goodwin inverter. It can be seen from the figure that the overall appearance of SS and NS presents a great improvement, and the NS machine only has 80% of the original SS volume. The weight is 70% of the original machine, and the small size and new weight are more in line with the installation and use of different environments.
Figure 1 Comparison of SS and NS
Integrated design
The biggest difficulty of the low-power string inverter is how to achieve better output characteristics, rich functional experience, smaller size and weight under the premise of ensuring the stability and quality under the optimal design cost.
This often requires a relatively clear understanding and planning of the cost and function of the machine at the beginning of the design. The integrated design is crucial in the design.
Goodwill's single-phase single-phase inverter (GW1000-NS~3000-NS) adopts a higher power density design scheme. This solution is contrary to the design ideas of existing inverters and does not employ more complex topologies and Too fancy hardware design solutions, but using a simple hardware topology, more advanced software control solutions and inverter control algorithms to obtain output characteristics and functions not lower than other models.
The integrated PCB design solution optimizes not only material costs but also installation costs and maintenance costs. The simple and neat design inside the box gives a clear feeling of no inconvenience in the installation process.
The integrated box design reduces the weight by 30% and the volume by 20% compared with the original product. Based on the overall optimized design, the aluminum magnesium alloy box, IP65 protection grade, natural cooling is still Goodwin The consistent features of the machine.
Table 1 Comparison of SS and NS parameters
2. Low voltage start
Although the low starting voltage will increase the difficulty of designing the internal power supply of the machine, such as power chips, transformers, and protection, the relatively suitable low voltage can bring many benefits to the machine.
(1) Low voltage can maximize the use of optical energy to generate electricity (especially in the morning and evening), to avoid frequent switching on and off of the rainy weather inverter and the resulting power loss, and to improve power quality.
The figure below shows the power generation status of the GW2000-NS machine under strong and weak light conditions. It can be seen that regardless of the conditions, the inverter presents a full time period (5:30 to 18:30) The power generation, 13 hours per day of power generation, did not result in frequent restarts due to weak PV panel energy.
Fig. 2 Sunny power generation
Figure 3 cloudy power generation
(2) In low-power systems (such as less than 1KW), there is no need for too many photovoltaic modules in series, and low-voltage start-up requires that at least three conventional components be connected in series to form a photovoltaic power plant. Small-scale photovoltaic power plants can provide more flexible installation methods. Reduce the impact of the regional environment.
As shown in the figure, in a system with less than 1kw, the NS series only needs three panels to complete the configuration of a photovoltaic power plant, which increases the flexibility of the system. Similarly, the photovoltaic system can achieve shadow effects on a complex roof. As a result, the efficiency of the system is improved.
(3) The lower voltage can make the inverter's input PV modules have the same orientation and inclination, which is very consistent with the characteristics of general household use. At the same time, low starting voltage can avoid a large number of components in series configuration, reducing the shadow effect of PV components, reducing the length of the cable in parallel with each other, reducing the cost, while the inverter with the advantages of volume and weight can be directly installed in the photovoltaic Beside the components, it is conducive to reasonable wiring, and it can also be used to maintain the photovoltaic system.
With the continuous development of distributed power stations, a large number of household inverters, high power generation, and easy maintenance are the core indicators for customers. The new generation of GW-NS series has captured this demand and emerged. It shows the direction of future development.
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