PVsyst is a globally recognized PV module simulation/modeling software that is used for all types of solar installations (residential, industrial, & utility). As a modeling tool, it takes into consideration a various range of real-life performance factors. The software can be used to virtually add a system of Tigo's optimizers, and even the new EI residential storage solution.
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- Simulation - Optimizer Selection
- Simulation - Detailed Losses
- Simulation - Near Shading & Module Layout
- Simulation - Incorporate monitoring benefits
In this article, the user will be guided into the addition of optimizers to an existing project. The steps described below are necessary to correctly represent the real behavior of an optimizer in a system; therefore, the process of setting up a virtual system and the simulation analysis may require more time than a standard project.
PVsyst supports module-level optimization in versions 6.48 and newer. Newer Tigo products, like: TS4-A-O 700W and EI residential solutions, are available only from version 7.2 onward.
In versions older than 7.2, it is not possible to add the latest optimizer or EI residential solution due to generational differences between the software. Solar Products change properties for each manufacturer, and sometimes, there are even differences between devices of the same manufacturer. Each new product listed, is set to obey particular rules within the newer versions of PVsyst.
Note: To be able to compare a system's production with (and without) the use of an optimizer, you will
need to run two variants of the same project. Only one of them will be equipped with TS4s,
which will include the added energy to the system. Therefore two detailed analyses will be
produced throughout two distinct reports.
Simulation - Optimizer Selection
To simulate the added energy production (from usage of Tigo equipment), go to Project Design and simulation and select a Grid-Connected system. Stand Alone systems can also utilize Tigo's technology; however, they are not supported by the current PVsyst software.
Define the project as usual until you arrive at the Variant stage, where Main parameters are defined.
At the System window, check the box next to Use Optimizer.
This will open a dialog box with different optimizer types.
Select the optimizer type you are using, for example, the TS4-A-O 700W. After choosing the product, if you are interested in getting more details on the optimizer, you can click on the Open button on the right. This will open a window with specific characteristics or parameters of the product chosen. For example, output I/V behavior according to the PV module chosen, the efficiency curve, or partial shading effect.
Simulation - Detailed Losses
After selecting the optimizers, and finishing the System tab, continue to Detailed Losses. This section is particularly important when optimizers are used; thus, you will be able to perform a much more realistic behavior of the PV modules over the lifetime of the project.
Once there, ensure that in the Module quality-LID-Mismatch>Module mismatch losses tab, the mismatch values are both set to 0. Newer versions of PVsyst will do this automatically, older versions will trigger a pop-up that will instruct you to do so. The reason behind this is that the inverter is able to find the best GMPPT point thanks to the impedance-matching technology of optimizers. Also, the optimizer and inverter don't work at constant voltage, contrary to other competitors' technology. Note that in the variant without optimizer, the two values must be set to default.
To simulate using aging, go to the Aging tab (or the Degradation tab in older versions of PVsyst) and select Uses in simulation. In this section, you will be able to take into account the most realistic module degradation of the PV module as it takes into account that module degradation mismatch increases over time (data published by NREL show that there are differences in the rate of degradation between modules. In year 5, this represents 1-2% additional losses, growing to ~4% in year 10 and 12% in year 20. Source: “Outdoor PV Degradation Comparison”; D.C. Jordan, R.M. Smith, C.R. Osterwald, E. Gelak, and S.R. Kurtz. NREL Conference Paper CP-5200-47704).
Since the benefits of optimization add up over a system's lifetime due to increases in mismatch due to variable module degradation, Tigo recommends simulating the halfway point of a system's life to quantify long-term ROI.
For instance, in the screenshot below, the value 10 has been entered because it is hypothesized the system would operate for 20 years (instead, if your system is expected to operate for 30 years, enter 15). Furthermore, this input needs to be changed in both variants with and without optimizers; thus, you will be able to diagnose the optimizer's energy gained over the full lifetime of the project.
Note, if you are running a project for a retrofit installation with optimizers, you need to choose the year that is positioned in the middle among the remaining year of the lifetime of the project. For example, a system has already run for eight (8) years and is expected to run for a total of thirty(30) years. Therefore the expected remaining years of running are 30-8=22yrs. Half of it, eleven (11), which added up to 8 (current year), will result in nineteen(19). Finally, this is the value representing the mid-value to be inserted into Simulation for year no.
If you would like to run additional simulations for increased accuracy in your financial calculations, run 3 (or more) simulations for each scenario:
- Un-optimized/Traditional: Year 1, Year 10, Year 20
- Optimized: Year 1, Year 10, Year 20
Simulation - Near Shading & Module Layout
Once you've completed selecting your detailed losses, continue with the site design and remember to define layout, orientations, and shade profiles in the Shading scene construction (go to Near Shadings > Construction / Perspective to activate). Without it, the effect of the optimizers won't be taken into account accurately in PVsyst.
At the construction phase, Shading scene construction, make sure to verify that the shade profile defined falls on the modules as expected and that the shading loss graph properly represents the behavior. This can be easily activated by pressing F12 and then playing in the bottom left corner.
Once done, go to Module Layout and define strings. This step isn't mandatory when designing a standard system but is crucial for modeling the effect of optimizers and accurately calculating the electrical effects of partial shading. More information about the Module Layout tab can be found on the PVsyst website. Module layout can be done automatically and usually doesn't require more than 1 minute for a simple system like the example above (Module arrangement > Set all modules). Make sure the orientation of your modules (portrait vs. landscape) in Module Layout matches their orientation in your Near Shadings construction.
Once Module Layout is defined, go back to Near Shadings and choose Use in Simulation > Detailed, according to module layout.
Simulation - Incorporate monitoring benefits
For an even more detailed analysis, you can take into account the monitoring benefits that the optimizer is bringing into the system. The monitoring of the optimizer, done with the implementation of Tigos datalogger CCA and TAP, will allow the end customer to increase the amount of time the system is running.
With Tigo's monitoring, it will be possible to improve runtime by detecting timely unexpected malfunctions and undiagnosed losses (diode failure not detected, focused maintenance not planned on time, etc.). This topic is extensively examined here.
To implement the optimizer's build-in monitoring benefits is suggested to set a discrepancy of 2% of unavailability (Detailed losses > unavailability > unavailability time fraction) between the simulation with the optimizer and without. This value will allow you to take into account the benefits that the optimizer is solely bringing with Tigo EI monitoring.
Finish entering other parameters as usual and press Simulation. The results will estimate the energy generated with the optimizers. The comparisons between the two reports results will allow you and your client to compute the actualized ROI scenarios with and without the optimizers.