When selecting PV modules, what is most concerned about is the material of the components. Which is better? And so on. For the inverter which is silently to pay, there are very few people who care about it! In the life cycle of photovoltaic power plants, the advantages and disadvantages of inverters largely determine the level of power generation revenue of photovoltaic power plants. In the initial investment of the entire photovoltaic power plant, the proportion of inverters is about 7%-10%, but in the actual operation of the power plant, the loss of revenue caused by one failure of the inverter is much larger than that of other equipment! Therefore, the reliability of the inverter is a key consideration for the entire plant revenue.
Hello everyone, my name is inverter.
In a photovoltaic power generation system, if an AC load is included, an inverter is required to convert the direct current generated by the solar module or the direct current discharged from the battery into alternating current. An inverter is such a device that converts direct current (DC) into alternating current (AC, typically 220V50HZ sin wave or square wave).
The surface of the PV module is a layer of tempered glass. The exterior color is mostly blue and black. It shines under the sunlight and is very delicate and beautiful.
In comparison, the inverter is particular low-key, it does not like to be directly exposed to the sun, but to stay in the shade to display its talent! Although its appearance is not good, but powerful!
We all know that the inverter can convert the DC power generated by the PV modules into AC power for us to use daily electricity. However, this square and ugly guy can do more than that.
The inverter also has automatic operation and shutdown functions and maximum power tracking control function to maximize the performance of PV modules and system fault protection!
Automatic operation and shutdown function
After the sunrise, the solar radiation intensity increases gradually, and the output of the photovoltaic module also increases. When the starting power required for the operation of the inverter is reached, the inverter automatically starts to operate. After entering the running state, the inverter monitors the output of the PV module at all times. As long as the output power of the PV module is greater than the minimum input power required for the operation of the inverter, the inverter will continue to run until the sunset. Even in rainy days, the inverter can operate normally as long as the starting voltage is reached. When the PV module output becomes smaller and the inverter output approaches 0, the inverter goes to standby state.
Maximum power tracking control
The output power of the photovoltaic module varies with the intensity of the solar radiation and the temperature of the photovoltaic module itself (the temperature of the silicon wafer). In addition, the photovoltaic module has a characteristic that the voltage decreases as the current increases, there is an optimum operating point at which the maximum power can be obtained. The intensity of solar radiation is changing, and it is clear that the optimum operating point is also changing. Relative to these changes, the operating point of the PV module is always at the maximum power point, and the system always obtains the maximum power output from the PV module. This control method is the maximum power tracking control. In photovoltaic power generation systems, the biggest feature of the inverter is the function of maximum power point tracking.
Inverters are divided into centralized inverters, string inverters, distributed inverters and micro inverters.
As the name suggests, centralized inverters convert the DC power generated by PV modules into AC power, and then boost and connect to the grid. Therefore, the power rating of the inverter is relatively large.
As the name suggests, string inverters convert DC power generated by PV modules directly into AC power, which is combined and boosted and then connected to the grid. Therefore, the power rating of the inverter is relatively small.
The distributed inverter is a new inverter form proposed in the past two years. Its main features are “centralized inverter” and “distributed MPPT tracking”. The distributed inverter is a product that combines the advantages of both the centralized inverter and the string inverter. It achieves the low cost of the centralized inverter and the high power generation of the string inverter. ".
Micro-inverters, also called module inverters, generally refer to inverters with a power of less than or equal to 1000 watts and PV module level inverter with maximum power peak tracking (MPPT). The full name is micro-photovoltaic grid-connected inverter. The micro inverter is only a few tens of volts of DC voltage, all connected in parallel, which minimizes the safety hazard. It is generally used in small photovoltaic power plants.
Ratio of inverter to photovoltaic module
Photovoltaic modules are one of the most important components in photovoltaic power plants. The cost accounts for about 50% of the grid-connected systems. The technical parameters of the PV modules are very important for the system design. Only when the parameters of the PV modules are clearly understood can the PV inverter be properly configured.
Inverter-related professionals have made an analogy between photovoltaic modules and inverters: "The photovoltaic modules are like expensive goods, and the inverter is like a horse. I would rather a big horse pull a small carriage than a small horse pull a big carriage. ”
When the power of the photovoltaic system is between 40-60% of the rated power of the inverter, the system has the highest efficiency and the longest life. In order to optimize the performance of the inverter, the PV modules and inverters have different ratios depending on the lighting conditions.
In class I area, the average sunshine time exceeds 5 hours, and the power generation time is calculated as 10 hours per day. It is recommended that the PV modules and inverters are configured in a 1:1 configuration with an average power of about 50%;
In class II area, the average sunshine time is 4 hours, and the power generation time is calculated as 9 hours per day. It is recommended that the PV modules and inverters are configured in a 1.1:1 configuration with an average power of about 49%;
In class III area, the average sunshine time is 3.5 hours, and the power generation time is calculated as 8.5 hours per day. It is recommended that the PV modules and inverters are configured in a 1.2:1 configuration with an average power of about 49.4%. In class III area with an average sunshine duration of less than 3 hours, the power generation time is calculated as 8 hours per day. It is recommended that the PV modules and inverters are configured in a 1.3:1 configuration with an average power of about 48.75%
Reminder: The montane area power stations are facing different directions. The complexity and orientation of the distributed photovoltaic roofs are different. The PV modules are not necessarily facing south. The tilt angle of the color steel tile roof is not the optimal inclination angle. The configuration of the inverter can be handled flexibly according to the actual situation.
In the life cycle of photovoltaic power plants, the advantages and disadvantages of inverters largely determine the income of photovoltaic power plants. The quality of the inverter provided by well-known brand companies is guaranteed, and will provide customers with quality services in order to maintain the corporate brand image.