If you want an inverter with less (or no) operation and maintenance, comprehensive selection is very important!-EEWORLD

Collect

The photovoltaic inverter is the core equipment for energy conversion in photovoltaic power stations. It is responsible for converting the DC power of photovoltaic modules into AC power and incorporating it into the public grid. It also serves as the information collection center of the entire power station, acting as the "ears", "eyes" and "nose" of the power station. For such an important device, the owner certainly hopes that there will be as few problems as possible, and it would be best if it never needs maintenance after installation. To achieve this goal, we need to have a deeper understanding of the inverter and understand clearly which characteristics of the inverter will cause failures and generate operation and maintenance.

In terms of selection, the standard warranty period for string inverters is 5 years. To ensure that the inverter will not fail due to its own reasons within 5 years, since many inverters are installed outdoors, the protection level must be above IP65. The larger the number, the better. The larger the number, the better the protection performance. l The casing processing technology is divided into traditional sheet metal technology and die casting technology. Die casting technology is better than sheet metal technology. l In terms of shell material, aluminum shell is better than iron shell.

Considering the maintenance-free design, the inverter should avoid the use of vulnerable and consumable parts as much as possible. Common vulnerable parts are: Fan: self-failure, loud noise, causing derating, regular maintenance. DC fuse: self-failure, increased loss, causing fire. LCD screen: self-failure. Button: self-failure.

Based on this aspect, a more reliable inverter should adopt natural cooling method, without DC fuse, and use Bluetooth, radio frequency and other methods to replace LCD screen and buttons.

In terms of component selection, the inverter, as a power electronic product, is composed of numerous electronic components. The reliability of the components directly determines the reliability of the inverter and is the cornerstone of the inverter's reliability. Well-known brands in the industry must be selected.

Components that affect the service life of the product should be examined in detail, such as electrolytic capacitors, film capacitors, IGBTs, relays, connectors, spoiler fans, etc. Fragile and consumable parts should be avoided as much as possible.

The string inverter is located between the photovoltaic panels and the public power grid, and plays the role of power conversion. The front end must adapt to the DC input voltage of the components, and the back end must adapt to the AC reference voltage of the power grid. Only when both sides are adapted can the machine work normally. If either side is not adapted, the machine will report a fault and fail to work.

l Considering the adaptability of DC voltage, the lower the DC starting voltage value, the stronger the adaptability; the wider the DC voltage range, the stronger the adaptability.

The wider the AC voltage range, the stronger the adaptability. Current harmonic THDI: <3%, the smaller the better. Output current DC component value: <0.5%ln, the smaller the better. Power factor: normal PF=1, the wider the adjustable range, the better.

In addition to the above matters regarding inverter selection, we can only ensure that the inverter's own reliability and adaptability are OK, which only solves "self" problems. As one of the electrical equipment in the photovoltaic system, the inverter must be designed and applied in conjunction with the entire system. Whether it can work normally is closely related to the system design and application environment in addition to its own reasons. If the system design and on-site construction are not standardized, "external" factors that exceed the normal working conditions of the inverter will be introduced, causing the inverter to fail to operate normally, thereby causing operation and maintenance.

In terms of the on-site application environment, the installation location of the string inverter is recommended as follows:

1. Install the inverter as close as possible to avoid long-distance routing of DC cables.

2. Try to install it on the bracket below the component, under the eaves, or on the outer wall (it is recommended to install a sunshade cover on the top) to avoid excessive external ring temperature causing machine derating or even shutdown.

(II) Electrical environment considerations

The grid voltage should remain stable. For power consumption areas with weak rural grids or strong inductive loads in factories, you can contact the manufacturer to appropriately relax the inverter output voltage range to avoid machine shutdown due to overvoltage or undervoltage faults.

2. The distance from the inverter to the grid connection point should be as short as possible. If there are objective reasons for long-distance wiring, it is necessary to pay attention to the inverter output voltage being increased by the cable voltage, resulting in overvoltage and disconnection from the grid. You can also contact the manufacturer to appropriately relax the inverter output voltage range.

3. The number of inverters connected in parallel should not be too many. It is better to have a certain load usage in the same grid-connected point. Too many inverters connected in parallel at one grid-connected point can easily cause harmonic interference, leading to system instability and affecting the normal operation of the machine.

There are many factors that affect the normal operation of string inverters. The above are some factors that need to be considered for the normal operation of the inverter analyzed by the author from three aspects: the inverter itself, system design and application environment. Only by taking these factors into consideration can we ensure the normal operation of the inverter for a long time and avoid unnecessary operation and maintenance investment.

Reference address：If you want an inverter with less (or no) operation and maintenance, comprehensive selection is very important!

Previous article：GoodWe's "first move" again: energy storage inverters begin to reap dividends
Next article：Barn Energy installs BYD energy storage batteries at 2 UK hydropower projects

Popular Resources
Popular amplifiers