Friends who are familiar with photovoltaic power stations know that photovoltaic grid-connected inverter is an indispensable part of photovoltaic power stations. The efficiency and annual power generation of photovoltaic power stations depend on it. Today, we mainly talk about the purchase points and common sense of photovoltaic grid-connected inverters.
1. Classification
Photovoltaic grid-connected inverter is a special device that inverts the DC electric energy generated through the photoelectric effect (solar energy is converted into electric energy) of the photovoltaic array (photovoltaic cell/module) into AC energy and then integrates it into the public power grid.
Different from conventional inverter products, it can follow the changes of sunshine conditions to the greatest extent and maintain the best power conversion efficiency and power output characteristics.
It can be divided into three categories: photovoltaic grid-connected micro inverter, series inverter, and centralized inverter.
Its application scope covers large-scale ground photovoltaic power stations, wind-solar complementary street lamp lighting, household roof photovoltaic power generation, photovoltaic agricultural power irrigation, and other fields.
There are many product styles, which can be divided into indoor and outdoor products. In response to different application environments, the product shapes are different. At the same time, its output power ranges from tens of watts to hundreds of kilowatts, or even megawatts, to meet different application needs.
2. Purchase
Photovoltaic grid-connected inverter is one of the essential core devices in photovoltaic power generation applications. The efficiency and annual power generation of a single photovoltaic power generation project depend on the product.
At the same time, it is also the core device for the safe operation of photovoltaic power generation. Consumers (users) can choose different power levels and different types of products according to different functions to meet the purposes of household power generation, industrial and commercial distributed power generation, and then special photovoltaic power station power generation of power production enterprises.
When purchasing photovoltaic grid-connected inverter, first pay attention to the identification on the packaging box and products to identify the input voltage range, voltage type, and maximum input current of the photovoltaic grid-connected inverter; Output voltage level, voltage type, and frequency; Maximum continuous working current, maximum output power, inverter efficiency, etc.
Secondly, it shall be checked that the random data of the product shall be complete, and the random data shall at least include the following contents: detailed product introduction (including technical parameter description), product installation instructions, operation instructions, and maintenance instructions, etc.
As a general industrial product, photovoltaic grid-connected inverter products are recommended to be used by nonprofessionals under the guidance of professional technicians. After purchasing products, nonprofessionals shall carefully read the product manual and other accompanying documents, and install and use them in strict accordance with the requirements of the accompanying documents. In case of doubt, they need to contact the manufacturer or manufacturer to ensure correct installation and use.
When purchasing imported products from abroad, attention should be paid to whether the foreign products declare the requirements of applicable domestic standards. At present, the current effective domestic product standard is Nb / t32004-2013 technical specification for grid-connected inverter for photovoltaic power generation.
In particular, attention should be paid to that the output voltage and frequency of foreign products should match the domestic public power grid point to which the products are connected. In addition, It should also be noted that the requirements for overvoltage and undervoltage protection implemented by foreign products are significantly different from those in domestic standards.
When using foreign products, the products will cause misoperation or refusal to operate, and there are huge potential safety hazards. It is not recommended for nonprofessionals to buy foreign imported products.
When purchasing photovoltaic grid-connected inverter, professionals should not only pay attention to the maximum conversion efficiency marked on the product nameplate but also pay attention to the maximum power point tracking efficiency of the product, as well as the power quality status (such as output harmonic, DC component, etc.) and overvoltage / undervoltage protection parameters when the product operates at medium and low power (50% rated output power and below).
The products shall be purchased and used according to different use environments. For example, household products shall pay attention to the electromagnetic compatibility and noise indicators of the products; For products used in high altitude areas (the altitude applicable to conventional products does not exceed 1000 m), pay attention to volume reduction;
For products used in extremely low temperature and high-temperature areas (the temperature range of conventional products is – 25 ℃ ~ + 60 ℃), pay attention to the adaptability of the product to the climate and environment, and leave sufficient safety margin for the normal use of the product.
3. Maintenance
The service life of photovoltaic grid-connected inverter is generally 10-20 years, and the quality level of products is uneven. If it is not used and maintained properly, it will seriously shorten the service life of photovoltaic grid-connected inverter, and even bring huge potential safety hazards.
Firstly, the technical parameters and indicators of the products to be purchased must be determined by professionals according to the user needs and then installed by professionals. After passing the acceptance with the permission of the local power department, the products can be connected to the power grid and put into use.
During daily use, it is necessary to regularly check that the input and output terminals of the product are firmly connected, the input and output wires and cables are not aging or damaged, and scratched, and the grounding wire is firm without fracture or falling off. If any problem is found, it shall be replaced by professionals.
Do not remove the input and output terminals at will. The input terminals have dangerous voltage during the day. The output terminals are always charged before disconnecting the power grid. The live parts of the terminals should be avoided from being exposed and not touched by personnel.
In daily use, in case of inverter operation fault, disconnect the protection switch connected to the power grid immediately, and ask professional personnel to eliminate the fault before starting the inverter again.
Before carrying out any maintenance work, first, disconnect the electrical connection between the photovoltaic grid-connected inverter and the power grid, then disconnect the electrical connection at the DC side, and wait for at least 5 minutes until the internal components are discharged. The maintenance operation shall be completed by professional technicians.
Nonprofessionals shall not disassemble the product shell. Professionals shall abide by the warning signs on the product during maintenance, wear anti-static gloves to avoid unnecessary circuit board contact, and pay attention not to directly contact the power devices and heat dissipation devices of the inverter with bare hands. The product still has a high temperature for a period of time after power failure, so they shall avoid scalding.
In the daily use of the product, clean the dust on the product surface and air inlet and outlet with a clean and soft dry cloth regularly to maintain good heat dissipation of the product and keep the product in a well-ventilated environment. It is not recommended that the maintenance of the disassembled shell of the product be operated by non-technical professionals.
