Meteo data and device models

11.4 Meteo data and device models

11.4.1 Meteo data

The software needs to read 8760 hours of meteo data in the power generation simulation module.

1. When there is no 8760 hour radiation and temperature data, users need to import meteorological radiation data in the "Meteorological radiation" (Chapter 2.2), and then select "Synthesis" in the "Source" of meteorological data. The software will automatically convert monthly radiation and temperature data into an 8760 hour data sequence.

2. In this mode, the software can directly import 8760 hours of meteorological data. The data source support includes Meteonom's "*. dat" files, Solargis's "*. csv" files, and users-defined "Excel file" table. If the users chooses "Excel file" as the data source, they first need to click the "?" button on the right, and then select "download" to obtain the template. users should fill in the customized meteorological data into the downloaded table document.

11.4.2 Horizon profile

"Horizon profile" refers to the obstruction caused by distant objects such as mountains, high-rise buildings, etc. to the PV array field. The condition for creating distant obstruction is that the obstacle distance must be sufficiently far, usually more than 10 times the size of the field, and can have a global impact on the entire PV field.

In the absence of distant obstruction, the horizon appears as a straight line, and the sun's elevation angle is 0 ° during normal sunrise and sunset. However, once there is distant obstruction, during specific periods of the year, when the sun's altitude and azimuth reach a certain angle, the incident light may be blocked by obstacles. From the perspective of the PV field, the time when the sun rises will be delayed, while the time when it sets will be advanced. Therefore, the amount of solar radiation received by the modules will decrease during the year.

In software, the impact of distant obstruction on the field is usually only considered in two extreme states: completely obstructed and completely unobstructed. This means that at a specific point in time, distant obstruction either cast shadows or completely obstruct the entire PV field area.

The software supports distant obstruction data sources including Meteonorm, PVGIS, and EXCEL files.

When selecting "Meteonorm" as data source, users need to choose the "*. hor" file exported by Meteonorm software.

When selecting "PVGIS" as the data source, the users’s computer must be connected to the internet. The software will automatically import PVGIS horizon data corresponding to the latitude and longitude settings set in the "Project settings" during simulation.

When selecting "Excel file" as the data source, users should first click the "?" button on the right, and then select "Download" to obtain the template. users need to fill in the customized horizon data into the downloaded table.

11.4.3 Ground albedo

It is crucial to consider surface reflection when calculating the amount of solar radiation received by the inclined surface of PV modules. Due to the close correlation between the amount of reflected radiation and the properties of environmental objects, the software use ground albedo as a parameter to describe the reflective ability of the earth's surface. The higher the ground albedo value, the better the reflection effect of sunlight, and the surrounding environment will also become brighter accordingly, resulting in an increase in the amount of reflected radiation received by the inclined surface of the PV module.

In the software, users can automatically apply the corresponding surface ground albedo values by selecting a specific surface type. However, these automatically inputted ground albedo values are based on the default values of surface reflectance in PVsyst software and are for users reference only. Users should make necessary adjustments according to the actual situation of the project.

After selecting the checkbox next to 'Monthly Reflectance', click on the word "Month albedo", and users can individually adjust the grond albedo for each month. For example, in the case where the project is located in a high latitude area, users can set different ground albedo values based on the actual situation, taking into account the possibility of snow accumulation in the winter project site.

11.4.4 Device model

The "Device model" is mainly divided into models for configuring modules and models for configuring inverters.

1) Configure module files

Configuring module files is a necessary and sufficient condition for completing 8760 hour power generation simulation.

Before configuring the model file, it is important to ensure that all arrays in the model are associated with the corresponding modules. For arrays that have not yet been associated with modules, such as models imported in reverse, the following steps can be followed to associate them:

①Click the "Create array" button and select the array that needs to be associated with the module from the "Select array" option;

②After completing the selection of the array, select the modules that need to be associated from the "Model" list. If the required module is not in the list, please use the "Create module" function to create it first.

③After completing the above two steps, click the "Update" button to successfully associate the selected module with the arrays. If the project contains multiple arrays, please select each array one by one and associate the corresponding modules.

The software will list all the used PV modules in the model, and users need to click the "Select" button one by one and specify the corresponding "*.PAN" file. Clicking "Select" will open the software's default "*.PAN" folder, users can select files from it or choose another location for "*.PAN" file.

2) Configure inverter files

Configuring inverter files is a necessary and sufficient condition for completing 8760 hour power generation simulation. Regardless of whether the electrcial connection is completed or not, please create the inverter before configuring.

When configuring inverter files, the following situations need to be considered:

①The model has not finished electrcial connection at all or has not finished completely. In both of the above states, the software calculates the 8760 hour power generation based on the unconnected state, using the relevant information of the first inverter in the inverter list as the basis for calculating the power generation.

Tips： 1) Completely unconnected model: It refers to a model that does not finish the power blocks at all, for example, when using reverse import, only the model of the array is imported; 2) Incomplete unconnected model: It may include the following situations: ①A model where some power blocks have been created, regardless of whether they have connected or not, but the remaining parts have not yet been created; ②All power blocks have been created, but either all have not been connected, or only some models have not been connected. Users can view in the "Device hierarchy" that if a array with "Arrays unconnected" or "NC string" is found, the model can be defined as an unconnected state.

②The model has fully connected. In this state, the model has completed the creation of all power blocks and the connection work within each block, and there is no "Arrays unconnected" or "NC string". At this point, the software will list all the inverters that have been used in the model. Users need to click the "Select" button one by one and specify the corresponding "*.OND" file. Clicking "Select" will open the software's default "*.OND" folder, users can select files from it or choose another location for "*.OND" file.

3. Inverter environmental temperature setting

In the process of calculating 8760 hours of power generation, the temperature of the inverter is usually assumed to be the external ambient temperature, which means that by default, the inverter is assumed to be installed outdoors.

At the same time as generating 8760 hour radiation data, the software will also automatically generate corresponding 8760 hour temperature data. Users can set the operating temperature of the inverter according to the actual situation of the project. After clicking on "Inverter temperature", the software will pop up the following parameter setting box:

When the checkbox to the left of "External ambient temperature" is selected, users can set a temperature drift value, which can be a positive or negative number. For example, if the temperature is set to increase by 1℃, it means that when calculating the actual temperature loss, the software will increase all temperature data by 1℃ in the 8760 hour data generated.

When the users selects the checkbox next to the "Fix temperature" option, they can pre-set a "Base temperature" and customize the "Increase acc globlnc". For example, if the "Base temperature" is set to 25℃ and the "Increase acc globlnc" value is set to 1℃/1000W/m ², then every time the current irradiation dose exceeds 1000W/m ², the temperature will increase by 1℃ accordingly. Assuming the current irradiation level reaches 2000W/m ², the actual temperature will be 27℃.

The software also supports the functions of "Allows overpower" and "High temp. limitation". Taking a 300kW inverter as an example, users can open its "*.OND" file through txt. In the file, we can view five parameters and their corresponding values: "PMaxOUT", "PNomConv", "TPNom", "TPmax", and "TPLim1".

If the checkbox to the left of "Allows overpower" is selected, when the ambient temperature of the inverter is below "TPNom", the output power of the inverter is the maximum output power, which is "PMaxOUT"; If not checked, the output power of the inverter is the rated power, which is "PNomConv".

If the checkbox to the left of "High temp. limitation" is selected, the output power of the inverter will begin to linearly decrease when the ambient temperature exceeds the "TPmax" setting value. If the ambient temperature further rises above the "TPLim1" threshold, the inverter will automatically shut down and the output power will drop to 0.

The following figure shows the relationship between the operating temperature and output power of the inverter when both the "Allows overpower" and "High temp. limitation" functions are enabled at the same time, providing users with intuitive reference:

Pout: Inverter output power

PMaxOUT: Maximum output power of inverter

PNomConv: rated output power of inverter

T: Environmental temperature

TPNom

TPMax

TPLim1