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Energy simulation

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Introduction

Energy simulation is a critical step in estimating the performance of your rooftop system. 
You can run a preliminary energy simulation directly in PVcase Roof Mount. This is useful if you would like to have an understanding of the energy yield early in the design phase.

 

How Energy simulation works

The Energy simulation feature is powered by PVcase Yield, which can handle highly complex shading scenarios and capture the intricate details of your system. 
Although Roof Mount’s Energy simulation is not fully based on PVcase Yield’s thermal-electric model, it does leverage the detailed irradiance analysis by PVcase Yield’s ray tracing technology, which is one of the most advanced algorithms in the market. Simulations are performed at hourly timestamps, resulting in 8,760 values aggregated into annual results.

Information used

  • Detailed 3D drawing, including shading objects and objects around the building
  • Module position (tilt angle, azimuth)
  • Supported modules:
    • Only c-Si (crystalline silicon) PV modules.
    • Only monofacial PV modules.
    • Only 1 type of module; must be the same dimensions and same power
  • Inverter weighted efficiency

Assumptions

The energy simulation model currently used by PVcase Roof Mount is based on the following assumptions:

  • All PV modules have an anti-reflective coating.
  • Losses associated with the electrical design of the PV system are approximated considering:
    • 2% DC cabling loss under Standard Test Conditions.
    • 2% module current mismatch loss (also called electrical shading loss).
    • 1.5% AC cabling loss under Standard Test Conditions.
    • 0% inverter clipping loss.
  • Module mismatch loss is constant at 1%.
  • Low light and module temperature losses are calculated applying the ADR model [1] and generalized coefficients for mono c-Si PV modules [2]. According to this model, the maximum power temperature coefficient of the PV module is -0.4%/°C and the low light efficiency at 200 W/m² is -2.2%.
  • Soling loss is constant at 1%.
  • Maximum power point tracking loss is constant at 1%.
  • DC/AC conversion loss is approximated by the inverter weighted efficiency.
  • System unavailability loss is 1% of the total AC energy yield.

However, you can adjust these default values to better reflect the characteristics of your project site.

RM_Energy-simulation_Edit-fields .png

Run an energy simulation and get a report

After adjusting the different parameters, you can easily run the simulation and see its results in a report, which you can save as an Excel/CSV file or a PDF.

Run a simulation

To run a simulation and get a report, follow the steps below:

1. Go to Energy simulation in the ribbon menu

RM_Energy-simulation_Ribon.png

2. Ensure your project location is correct

RM_Energy-simulation_Location.png

3. Select the module and inverter model from the drop-down (Component library)

RM_Energy-simulation_Module-inverter.png

4. Click Calculate; the Data retrieval process will start

RM_Energy-simulation_Calculate-process.png

5. Once the calculation is complete, the Energy simulation menu will appear again with a confirmation as well as an overview of the simulation results

RM_Energy-simulation_Calculate-ready.png

Get a simulation report

You can see and download your simulation report in two formats:

  • PDF

  • Excel/CSV file

RM_Energy-simulation_Export-excel-PDF.png

PDF format

The PDF report includes a summary of the simulation. To view it, click Export to PDF. Once generated, you can also save it.

RM_Energy-simulation_Report.gif 

The PDF report includes:

  • System characteristics
  • Performance information:
    • AC annual yield
    • AC specific yield
    • AC performance ratio
    • AC monthly yield (graph)
  • Generalized losses

CSV format

You can also download the report as an Excel/CSV file, facilitating further analysis for your sales proposals. To do so, click Export to Excel.

RM_RN_1.55_Energy-sim-excel-export.gif

 

The CSV file report is more comprehensive and includes the following:

  • Global Horizontal Irradiance
  • Diffuse Horizontal Irradiance
  • Direct Normal Irradiance
  • Direct Horizontal Irradiance
  • Ambient Temperature
  • Wind Speed
  • Effective In-plane irradiance
  • Effective AC Power Output

 

FAQs

How is performance ratio calculated?

The performance ratio is calculated as the ratio between the annual AC energy output and the annual theoretical energy output of the PV system. The theoretical energy output is calculated as the annual in-plane irradiation multiplied by the conversion efficiency of the PV module under Standard Test Conditions (STC).

 

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