On January 13, the 5th Home PV System Promotion Conference (Shijiazhuang Station) came to an end. Photovoltaic counterparts from all over the world gathered together to discuss the development of distributed photovoltaics. Yuan Ruimin, Product Manager of Guruwatt, was invited to attend the conference and shared with the participants how to select the inverter for distributed PV systems.
Yuan Zhimin pointed out: "With the development of the photovoltaic market and the advancement of reform, the distributed photovoltaic market is developing better and better. Previously speaking, distributed, it is considered to be distributed on the roof, such as household and industrial and commercial roofs. But now Distributed also includes terrestrial distributed types such as wasteland, barren hills, fish ponds and greenhouses. Then, the selection of inverters is particularly critical. When selecting inverters for distributed PV systems, you need to pay attention to these five points, matching scenarios, Efficient power generation, safe and reliable, grid friendly, intelligent operation and maintenance."
Five elements of distributed photovoltaic selection inverterFirst, it is necessary to match the inverter from the application scenario of distributed photovoltaics, and to select the appropriate inverter according to local conditions in order to play the maximum role. How to choose the inverter model? Single or three phase? These depend on the condition of the roof, the roof or the courtyard of the home, and the installed capacity is small. Generally, single-phase or three-phase grid-connected inverters are selected. When the roof area is too large, three-phase inverters are selected; industrial and commercial roofs, Complex mountain and greenhouse projects, for scenes with irregular orientation, prone to partial occlusion, large installed capacity, and low-voltage or medium-voltage multiple grid-connected voltages, generally select three-phase string inverters; for northwestern regions For large ground and desert power plants, a centralized box inverter is recommended.
Second, the key factor in choosing an inverter is efficient power generation. To achieve high-efficiency power generation in photovoltaic power plants, one indicator is the conversion efficiency of the inverter. The inverters often see the two concepts of maximum efficiency and weighted efficiency. What is the difference between these two concepts? Maximum efficiency is the best performance of the inverter in the best case. The weighted efficiency is the overall performance of the inverter. Inverter can achieve high-efficiency power generation is a comprehensive manifestation, so it seems that the weighted efficiency is more manufacturing significance.
Another key indicator is MPPT efficiency, with both dynamic and static strategies. For the time being, the algorithm of static MPPT efficiency is not much problem that most manufacturers can achieve. The key is the dynamic MPPT efficiency. In the actual working environment of the inverter, the conditions of illumination and temperature are constantly changing. Inverter conversion efficiency and MPPT efficiency, which affect the power generation of the inverter, can prolong the power generation time and thus increase the power generation.
Third, the distributed photovoltaic system is close to the user side, and safety and reliability have become an important factor in selecting an inverter. Owners and developers want the power station to operate reliably and safely for 25 years. 1. Realize group string monitoring, which can perform detailed monitoring on each string, and timely discover problems such as line faults, component faults, and occlusions, and reduce fault location time. 2. The inverter has protective function, it must be able to prevent fire. For example, the color steel tile roof and mountain scene are prone to fire; it can prevent lightning strikes. For example, the roof and mountain scenes are prone to thunderstorms; to prevent PID and defense Electric shocks, such as fishing lights and agricultural light complementary scenes often have operations or work personnel. 3. Inverter heat dissipation design, electronic device life 10 °C rule: for every 10 °C increase in device ambient temperature, life expectancy is reduced by half. 4. Consider the process design and period selection of the inverter. With good design, it is necessary to carry out a large number of experimental verifications, such as waterproof, dustproof, high and low temperature.
Fourth, the choice of inverter should consider grid friendliness. In the photovoltaic system, the inverter is an important tool for converting light energy into electrical energy. The front is connected to the light, followed by the power grid. There are three indicators of inverter grid friendliness, power factor, current harmonics, and DC components. Power factor PF, PF=1 is ideal under normal conditions, the smaller the current harmonic THDi, the closer to the sine, the DC component DCI, the smaller the ideal.
Fifth, intelligent operation and maintenance, different monitoring schemes are selected for different scenarios, and there are three modes of non-operation and maintenance, such as remote monitoring, online customer service, and remote operation and maintenance.
It is understood that Guruwatt is established in 2010. By the end of 2016, the cumulative global shipments exceeded 600,000 sets, and it is the only manufacturer with 60,000 inverters operating stably for more than 5 years. As China's largest exporter of household energy storage systems, Guruwatt is committed to the world's largest provider of user-side smart source solutions.
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