Expected System Yields

Via the ‘Results’ button on the system page, you can navigate to the ‘Expected yield’ page. Here you will find a tonne of information on the expected performance of the system you designed. This is the most important source of information to further optimize the power output of your system, before creating a quote and selling the project.

Both for the system as a whole and all the individual installation areas, Helios provides you with detailed calculations on shade, yield and maximum power. The following tables are shown:

  • Yield per installation area: this will give you the nominal power and expected yields for all areas within your PV system, as well as the maximum AC power and currents.
  • Shading profile: you can select different shading profiles. The ‘modelled’ profile will give the most accurate results, since it’s based on the designed model and takes all shading and string groups into account.
  • Shading analysis: in this table you can see the effect of shading on the modules, caused by obstacles within and around your installation areas. It will also show what improvements are obtained by the different mitigation methods like string groups and optimizers. Lastly, the possible yield for when all modules are equipped with optimizers is calculated, to show the (most often limited) effect of this.
  • Yield per month: the yield for the entire system, split out by month and presented in either a graph or a table.
  • Installation area details: the same table, but it lets you select one of the installation areas within the PV system to zoom in on its details. By selecting an area you will also be presented with a horizon plot of the most shaded module within that area, and an overview of the shading losses. Here a colour scale going from green to red will indicate the percentage of shade loss per module.
  • Expected yield: this shows the yearly expected yield for the entire system together with cumulative values.
  • kWh guarantee: this table holds the different options available for the kWh guarantee. The guaranteed yields and related costs are calculated based on the system design.
  • Energy balance: an extensive calculation of the system’s yield, showing how the expected irradiation on the given location leads to the projected yields.

When yields are not as expected, there are many ways to correct and edit your system design. Different measurements will lead to different results that will heighten the expected yields to more or less effect. Based on the expected yields, you may:

 

  • Create and/or edit string groups: with string groups, the yield for each string group is calculated based on the most shaded module within the group. If only a small number of the modules in your system is shaded, isolating them in their own string group will stop them from influencing the rest of the modules negatively. Yields can be further enhanced by creating more string groups, but make sure they stay in line with the number of MPPT’s and DC inputs on the selected inverters.
  • Add optimizers: an optimizer will isolate the yield for a single inverter from the rest of the string, so a single shaded module will no longer limit the yield of an entire string when it’s equipped with an optimizer. Make sure to follow Tigo optimizer design rules
  • Remove modules: even with string groups and optimizers added to your module, some modules are too heavily shaded. Removing the most shaded modules as indicated on the shading losses image, will enhance yield in kWh/kWp. By doing so, nominal power becomes less, but the remaining modules will perform better, leading to a more economic installation.
  • Adjust height map: if the horizon plot and the shading losses image show unexpected results, you may need to change the height map. Make sure the area details are set correctly, and the height map represents the current situation. You may need to add masks or obstacles to correct the height map.
  • Change the orientation of the modules: for flat roof systems, it may be effective to change azimuth of the modules, particularly if the modules are partly shaded. Also changing from Matrix Universal to Symmetrical and vice versa will affect yields.

In order to generate the most accurate expected yields our model uses a variety of data sources, including

  • Historic irradiance levels
  • Historic temperatures
  • Performance history of thousands of Autarco systems

Yes, our yield model is fully endorsed by LLoyd’s of London who insures our production guarantees. Our yield predictions are also accepted by most major banks.

In most cases differences between Autarco’s expected yields and other software modelling tools are caused by;

  • Difference (or lack) of shade modelling
  • Different assumptions on system availability (Down-time) which has a big impact on expected performance ratio (PR).

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