Frequently Asked Questions: Photovoltaics
We have again compared the simulation results from PV*SOL® with actual measured PV module data. For all PV modules, for which manufacturers provide details on the part-load performance of their PV modules, the projected yields after simulation with PV*SOL® correspond very closely with the measured results of the PV modules, due to the precise efficiency curve.
If, however, the manufacturer has not provided details, so that for these PV modules the corresponding efficiency curve in PV*SOL® must be based on standard part-load performance data, the simulation results are considerably lower compared with the measured results, at least for crystalline PV modules.
In order to meet the current development trend for crystalline PV modules, in version 5.5 of PV*SOL Expert the standard part-load performance efficiency curve has been adjusted. Therefore the yield can increase up to approximately 3% in the latitude regions of 30° and 5% in the mid latitudes (50°).
This concerns the following crystalline cell types:
- Si monocrystalline
- Si polycrystalline
- EFG
- ribbon
- microcrystallineThe Sunny Tripower inverters have 2 asymmetrical MPP trackers and there are thus a few things that need to be taken into consideration with the design.
In the 2D-planning you have to design to sub arrays. One for the modules that you want to connect to the input A of the inverter and one for the rest of the modules which you want to connect with input B.
The main inverter (input A) is saved in PV*SOL’s inverter database with a reference for the inverter type. In addition, for the second array, the Tripower Extraeingang inverter (input B) must be selected (for all models the same).
Input B can bear up to 8.8 kW in a maximum of one string. This actual installed power must then be withdrawn from input A. If you want to configure input B with more than 2 kW, you will need to go to "Databases" - "Inverter" - "Grid Connected" and select the inverters that match the power values correspondingly (input A low, input B high) and save in the database as a user-created data record using "Save As".
As a rule, the majority of modules should be connected to input A and the rest of the modules to input B (ewith g, 60 modules - 2 strings with 24 modules to input A and 1 string with 12 modules to input B).
In 3D planning you have to select the self-created Tripower records as appropriate inverter combination.
It is recommended that a test using the manufacturer’s design tool is carried out!
Here you can find a video tutorial on this subject.
Go to the menu "System" - "Technical Data" and then choose the "PV Array" tab. For mounted systems select the installation type "Free-Standing". You can either enter a set number of modules (select "Define Module Number") or you can select "Determine Output from Roof Area", in which case you can click on the "Roof Parameters" button to open the corresponding dialog. With mounted systems ("Free-Standing" installation type) and "Determine Output from Roof Area" when you click on the "Roof Parameters" button an additional dialog appears showing the minimum distance between modules.
Please note that mutual shading of the modules is not taken into account in the simulation.
How do I design a mounted system in the 3D visualization of PV*SOL Expert? Learn more here.
The current feed-in tariffs can be downloaded from the Download area of our website. Please save and extract the *.zip file in the tariff folder of your PV*SOL program. Under "Options" - "Paths" - "Electricity Tariffs", you can see where the tariff folder is kept on your computer. If you want to set the new feed-in tariff as the "Standard Feed-in Tariff for New Projects", you can update this under "Options" - "Settings" - "Projects".
Yes, it is planned to include this function in future versions of PV*SOL.
Your module does not have 100W, but only 98,5W. The output given by manufacturers is often rounded. The actual nominal output, as calculated in PV*SOL, results from the MPP current and MPP voltage under standard test conditions (STC).
The automatic update function from within PV*SOL does not work if the PC you are using does not use the standard internet settings. We can provide you with the latest module and inverter database for PVSOL by download link, so that the database can be imported locally. Please use the following link to load the latest database and then save the PVSOL.mdb file locally on your PC: www.solar-software.de/update/pvsol/db2/pvsol.mdb Please also remove the tick set against the (Internet) Updates option "Automatically 1x per Day on Starting PVSOL" (menu: Options -> Settings; Update Check worksheet) Please then enter the local path, where the PVSOL.mdb file has been saved, in the field under "Database Import / Local Directory:". You can then start the Database Import faciltiy.
- Is it possible to perform calculations for mounted systems in the 3D visualization of PV*SOL Expert?
Yes. To do this, please go to the module mounting window and define your mounting system by using the PV*SOL standard rack.
Please note that this tool is only available starting PV*SOL Expert 5.0.
Yes, because the module array is simulated in terms of its installation type, azimuth and tilt angle of the modules and its height above the ground, independent of whether the modules are installed on a roof or on the ground. In the 2D planning you should select "Free-Standing" for the installation type. The height above ground can be defined in the "Losses" window. In the 3D visualization set the building height to 0 in the terrain view window.
Start a new project with the option "System Planning without 3D visualization". Open the "Technical Data" dialog. In the "Technical Data" dialog window please change to the "PV Array" tab and choose the option "Create preview of roof layout with Photo Plan". The button "Photo Plan" is now activated and you can access to Photo Plan.
Please note that Photo Plan is only available starting PV*SOL Pro 4.5 and PV*SOL Expert 4.5.
Please go to the "Electricity Tariff" window by choosing "Conditions" and then "Tariffs (Grid Connected Systems)" in the menu bar. Now select the "Net Metering" option. Leave the window with the "OK" button. Your entries made previously retained when switching between the grid concepts.
The discount is taken account of in the loan interest for the first year.
A horizon with an elevation angle of 2° all-round is entered as a shading object as a default in the PV*SOL Expert software. This setting leads to a small yield reduction due to horizon shading. It has been selected because all locations worldwide, and residential areas in particular, effectively never have a horizon that is completely free of shading. If you wish to delete the horizon object, please select the "Horizon" menu item in the terrain view and delete it by changing the elevation angle from 2.00° to 0°.
The programme will automatically check for updates and additions to the database if you select the option "Automatically 1x per Day on Starting PV*SOL" in the menu "Options" - "Settings" - "Update Check".
You are also able to carry out an "Update Check" manually by clicking on the button "Check Now" in the same dialog. Internet access is required for both of the above options.
If the software and database installed on your PC are the latest versions, you will receive the following message: "The latest versions of both PV*SOL and the Database are installed." Otherwise the following message will appear: "A database with a more up to date version is available." By clicking on "Install Now…" you can start the update.
In PV*SOL express you can plan pv systems up to 1 MWp.
In the 2D planning of PV*SOL Pro and Expert there is a limit of 65535 modules per sub-array. This means that the output entered in the "Quick Design" dialog cannot exceed the output for the selected module x 65535. In the 3D visualization of PV*SOL Expert the module number is limited to 2000.
For example, if the selected module only has 36 W, it is only possible to enter a target system output of 65535 x 36 W = 2.3 MW.
This is not possible directly from PV*SOL. However, you can copy the table to the clipboard (button “Copy Table”) and then paste it into e.g. Word or Excel. You can then print the table from there.
If you want to determine the number of modules by using the roof dimensions you have to select the option "Determine Output from Roof Surface" in the "Technical Data" window. The button "Roof Parameters" beside this is then activated. Click the button to access the "Roof View" window.
The climate data are stored in a database and can be viewed by using the menu item "Results" - "Energy and Climate Data". Select the desired data category, like "Radiation", "Wind" or "Temperature" and press the "OK" button. To view more detailed results you can scale the graph via the "Axes" - "X-Axis" menu. Choose your desired time and display interval. The graph can also be viewed in tabular format. To do this click on the "Table" button. The table can be exported for further processing, e.g. in Microsoft Excel.
The feed-in tariff to be used for all new projects can be loaded via the menu "Options" - "Settings" - "Projects". Click on the load file icon next to the "Standard Feed-in Tariff for New Projects" option and select the preferred tariff file.
The data correspond to the first full year of operation.
Yes. In the dialog "Technical Data" - "PV Array" you can select between single and dual axis tracking:
- With single axis tracking, an azimuth of -90° to 90° is taken into account, with a vertical rotation axis.
- Dual axis tracking calculates the situation with movement of both rotation axes.
In both cases, the technical limits of the tracking system are not taken into account. This means that if the tracking system can only be rotated up to a certain angle, this is not taken into consideration by the software.
To use this feature in PV*SOL Expert please select system planning without 3D visualisation.
The PV Solar Surface Area is the area that forms the basis of the manufacturer’s measurement of module efficiency. For simulation, the program determines the Solar Surface Area from the calculated power and efficiency (ETA), using the following formula:
PV Solar Surface Area = Nominal output(STC) / (1000 W/m² * ETA(STC))
In some cases, the resulting figure is different from the Gross PV Surface Area. If, for example, the manufacturer does not take the module frame into account when calculating the ETA (STC), in order to obtain a better ETA (STC), the Solar Surface Area will be smaller. For a Solar Surface Area that corresponds to the Gross PV Surface Area, you should click on the calculator symbol to calculate the Module Efficiency.
With PV*SOL you can build modules and inverters from different manufacturers into a system and mount these at different orientations and inclinations. To do this, the program splits the system into a number of different sub-arrays.
A PV array/sub-array is a PV surface unit made up of the same types of module mounted together and set at the same angle and orientation. If you have a number of inverters connected to an array, these also have to be all the same type and configured in the same way.
You are able to define up to 6 sub-arrays in PV*SOL.This message means that an important hardware feature for the 3D display is not available on the graphics card being used.
Possible reasons for this:
- DirectX version lower than 9.0c.
- DirectX 9.0c is not supported by your graphics card.
- You are using a terminal server solution. The DirectX graphics component is not capable of running on a terminal server.
- You are using a Windows emulator. Not all Windows emulators support DirectX.
In many cases an update of your graphics card drivers can help.
Whether the system is roof-integrated or roof-parallel does not play a decisive role in visual planning in the 3D tool, and thus the 3D tool does not yet differentiate between the two. Categorisation of the system as being roof-integrated or roof-parallel only occurs after 3D planning has been completed and you have returned to PV*SOL in the dialog "Losses" under Installation Type. Please select the option " With Ventilation" if your system is installed on a substructure parallel to the roof cladding or "Without Ventilation" if the system is integrated into the roof cladding. The calculation then takes the corresponding temperature situation into account. You can access the dialog "Losses" via the losses icon in the PV*SOL Expert main menu (a white bar in a red circle).
The decisive factor for the yield is the part load efficiency. In this area, amorphous modules usually have a better efficiency than monocrystalline modules. The part load efficiency is presented in the efficiency characteristic curve which can be displayed under "Databases" - "PV Module" - "U/I Char. – Part Load" by clicking the "Efficiency Char. Curve" button.
No, with our PV programs it is not possible to calculate costs. There are no component prices or other costs included in the software. Every user will need to find out the costs for the planned system themselves. The system price determined by the user has to be entered in the "economic efficiency calculation" dialog and forms the basis of the economic efficiency prognosis. Default values are provided in the economic efficiency calculation and should not be viewed as average or empirical values. They need to be adjusted by the planner.
Yes. You can print the roof layout as a separate document via the menu "Results" - "Project Report" - "Roof Layout". This function is only active if the roof layout has been used for the project planning. Alternatively, the roof layout can be integrated in the detailed project report via the menu "Results" - "Project Report" - "Detailed Project Report".
In theory, yes. To do so, you have to set the required central file path under "Options" - "Paths" and then copy the locally installed files from the local folder into the new central folder.
Please note the following potential problems:- Special network configurations, server operating systems or access rights can prevent access. Unfortunately, we cannot guarantee operability under your concrete network conditions.
- The automatic database update for the component database (module and inverter data) may not function because special network configurations or security systems, e.g. firewalls, on the server do not allow this.
- You should make sure that only one user at a time carries out the automatic update for the component database.
- Simultaneous access by a number of users to the same project is not supported by the software! This can lead to data losses.
Many PV*SOL customers do, however, successfully use data that is stored centrally.
Please note that in case of problems with the network configuration Valentin Software in general cannot give support.
The database delivered with the programme includes values from GEMIS (Global Emission Model for Integrated Systems) that were first published in 1990 by the German state of Hessen (Environment, Energy and Federal Affairs Ministry). You can view and change the values via the menu "Databases" - "Pollutant Mix". Further information on GEMIS is available here.
All modules are calculated with the part-load characteristic curve (efficiency or ETA curve). The specific part load operation for the modules is in some cases given by the manufacturer (see "Databases" - "PV Module" - "U/I Char. – Part Load"). In all other cases a characteristic curve is used that is specific to the cell type. It is possible to select from 11 different cell types. For the 5 thin film types: amorph, HIT, CIS, CdTe and triple a-Si, standard characteristic curves are available for typical part load operation. For the other 6 cell types the standard operation for monocrystalline modules is used.
The specific annual yield is calculated as follows:
specific annual yield = (energy produced by PV generator – energy from grid / (exact) PV output
Four decimal places are included in the calculation. The value for the energy from grid can be viewed in the "Results" – "Annual Energy Balance" dialog and in the Detailed Project Report.
The energy from grid is comprised of the appliance’s electricity requirement which is met by the grid (if connected) and the PV system’s own requirement (for inverter stand-by and night use).
At the current time, module tolerances are not taken account of in the calculations carried out during simulation. However, they will be in a future version.
The net present value is displayed, and not the amount of the feed-in tariff. This means that the feed-in tariff every year is shown minus the capital interest calculated since the starting point. If you wish to see the course of the feed-in tariff over time without interest being taken into account, select “Payment Behaviour without Interest” in the dialogue “Viability Calculation” on the “Graphics” or “Tables” windows. This selection has no influence on the results and the graphics in the project report; net present values are always shown here.
