EN 
PT_BR 
PVSyst is powerful software that should be part of every photovoltaic designer's toolbox. Shadow analysis, energy production estimation, loss study and economic analysis are some of the features that PVSyst provides. Among many other facilities that the software presents, the “View dimensioning” function (Show sizing) on the “System” screen (System) is an extremely useful feature offered by PVSyst. This feature makes the day-to-day life of those who size and design photovoltaic systems much easier.
The task of making inverters and photovoltaic arrays compatible requires thorough inspection of the characteristics present in the component data sheets. Some characteristics and factors that must be analyzed are: maximum current and maximum voltage supported by the inverter, operating range for tracking the maximum power of the inverter, maximum current of the photovoltaic modules, voltage variation of the photovoltaic modules as a function of temperature, maximum number of string modules and inverter overload factor and other things. The task of checking all these parameters, which can consume considerable time for the designer, can be carried out in the blink of an eye in PVSyst. In addition to the reduced working time, the reduction in the margin of error in sizing is a huge advantage of this tool. In the example shown in Figure 1 we have a 9 kWp system composed of 22 410 Wp modules from Jinko Solar and 1 SMA Sunny Boy 8000 grid-tie inverter, with an AC output power of 8 kW. The result of the “View Dimensioning” tool for this configuration is shown in Figure 2.
Figure 2 (PVSyst screen) presents a visual summary of all the characteristics of the inverter and the photovoltaic array (2 strings of 11 modules in this example). Among other things, in this figure you can instantly view and check the compatibility of the following project parameters: Inverter operating voltage range (Vmpp Min – Vmpp Max): It is in this range that the maximum power point of the module arrangement must be located. In Figure 2 we see that the point of maximum power lies exactly within this range. Absolute maximum inverter voltage: is the maximum voltage that the inverter can receive at its terminals. It is not the operating voltage, but the maximum open circuit voltage (Voc) that the photovoltaic modules can apply to the inverter in any situation. In Figure 2 we see that the voltage Voc at 5 oC (lowest temperature considered in this project) is lower than the limit supported by the inverter, therefore the project is safe in this criterion. Maximum current supported by the inverter: is the maximum current that can be received at the input terminals on the DC side of the inverter. In Figure 2 we see that the short-circuit current of the two strings (20 A approximately) is lower than the maximum current supported by the inverter. Inverter maximum power curve: The parabolic dashed line seen in Figure 2 shows the inverter's DC input power limit. The fact that the point of maximum power (at the two temperatures considered in the project) is below this line indicates good compatibility between the arrangement and the inverter. When the maximum power point exceeds the dashed line, the occurrence of power limitation during inverter operation becomes more likely. Inverter overload factor – Parranjo/Pinverter ratio: the inverter overload factor is around 13% in this project, as shown in Figure 2. This means that the nominal power of the photovoltaic array (in STC) is 13% higher than the nominal power (AC) of the inverter. Slight inverter overload is very common in photovoltaic systems, considering that modules will rarely operate at their rated peak power. In Figure 2 we see the characteristics found in the JKM410M-72H photovoltaic module datasheet from Jinko Solar. Without the help of the “See PVSyst sizing” tool, it would be necessary to search for this data, calculate the voltage and current of the array and adjust the open circuit voltage according to the lowest temperature considered in the project. All this information is readily available by PVSyst, saving effort and minimizing the possibility of failures when choosing the characteristics of the photovoltaic array and inverter in a project.
