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The Simulation Settings page allows you to configure the prediction timeframe and select the sub-models used for irradiance calculation, module performance, shading analysis, and degradation. These settings control the algorithms applied during the energy prediction simulation.
Simulation Settings

Simulation Settings

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Overview

The Simulation Settings page is organized into the following sections:
  1. Timeframe — Set the prediction start and end dates, and access uncertainty analysis configuration. Weather file summary information is displayed for reference.
  2. Irradiance Models — Select decomposition, transposition, and circumsolar treatment algorithms, plus toggle options for using weather file DNI and pre-calculated POAI values.
  3. Module Related Models — Choose incidence angle modifier (IAM) and module temperature calculation methods.
  4. Shading Models — Configure direct and diffuse shading calculation approaches.
  5. Degradation — Define long-term degradation parameters including annual rates and LeTID modeling.

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User Inputs (Timeframe)

#InputTypeUnitsDescriptionRelated Documentation
1Start DateDate Picker—Beginning date and time for the prediction simulation. Must fall within the weather file date range shown in the summary panel.—
2End DateDate Picker—Ending date and time for the prediction simulation. Must fall within the weather file date range shown in the summary panel.—
3Show Uncertainty AnalysisButton—Opens the Uncertainty Analysis configuration panel to define P-value selections and uncertainty parameters for probabilistic energy estimates (P50/P90/P99).Uncertainty Analysis
The Timeframe section also displays Weather File Summary information (read-only):
  • Weather File Name — Name and location coordinates of the loaded weather file
  • Start Date / End Date — Date range available in the weather file
  • Time Step — Temporal resolution of weather data (e.g., 60 min)
  • Duration — Total years of weather data

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User Inputs (Irradiance Models)

#InputTypeUnitsDescriptionRelated Documentation
4Weather File DNIToggle—When ON, uses Direct Normal Irradiance (DNI) values directly from the weather file. When OFF, DNI is calculated from GHI using the selected decomposition model.Horizontal Irradiance
5Frontside POAIToggle—When ON, uses pre-calculated frontside Plane-of-Array Irradiance from the weather file instead of calculating via transposition models.—
6Backside POAIToggle—When ON, uses pre-calculated backside irradiance from the weather file for bifacial modules instead of calculating via the bifacial model.Bifacial
7DecompositionDropdown—Select the algorithm for decomposing GHI into direct and diffuse components. Options: None, DIRINT, Erbs, Reindl.Decomposition
8Circumsolar TreatmentDropdown—Select how circumsolar radiation is handled in transposition. Diffuse treats circumsolar as part of diffuse; Direct treats it as part of beam irradiance.Transposition
9TranspositionDropdown—Select the transposition model for calculating plane-of-array irradiance from horizontal components. Options: Perez, Hay-Davies.Transposition Models
10Perez CoefficientsDropdown—Select the coefficient set for the Perez transposition model. Options: PlantPredict, All Sites Composite 1990, All Sites Composite 1988, Sandia Composite 1988, or location-specific sets (USA, France, Phoenix, Elmonte, Osage, Albuquerque, Cape Canaveral, Albany).Perez Model
#InputTypeUnitsDescriptionRelated Documentation
11Incidence AngleDropdown—Select the Incidence Angle Modifier (IAM) model. Options: None, Tabular IAM, Physical IAM, Sandia, ASHRAE.Incidence Angle Modifier
12Module TemperatureDropdown—Select the module temperature calculation method. Options: Heat Balance, NOCT, Sandia, DC Field Defined.Module Temperature

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User Inputs (Shading Models)

#InputTypeUnitsDescriptionRelated Documentation
13Direct ShadingDropdown—Select the direct beam shading calculation method. Options: Module File Defined Shading, None, Linear, Fractional Electrical Shading. Note: This field is disabled when a 3D scene has been configured; shading settings are controlled via the 3D Scene Overview page.Direct Beam Shading
14Diffuse ShadingToggle—When ON, applies diffuse sky shading factors to account for horizon obstruction and row-to-row diffuse blocking. When OFF, no diffuse shading is applied.Diffuse Shading
When a 3D Scene is configured for the prediction, the Direct Shading dropdown is disabled. Shading calculations are controlled by the settings in the 3D Scene Overview page, which provides more advanced shading analysis options.

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User Inputs (Degradation)

#InputTypeUnitsDescriptionRelated Documentation
15Number of YearsText FieldyearsTotal project lifetime for degradation calculations. Determines how many years of degraded energy output are calculated.—
16Degradation ModelDropdown—Select the degradation calculation method. Options: Linear DC, Non-Linear DC, Linear AC, Stepped AC.Degradation
17Degradation RateText Field% Per YearAnnual degradation rate applied according to the selected model. Typical values range from 0.25% to 0.7% per year for crystalline silicon modules.Degradation
18First Year DegradationToggle—When ON, applies degradation starting from Year 1. When OFF, Year 1 energy is calculated at full capacity with degradation beginning in Year 2.—
19Use Leap YearsToggle—When ON, accounts for leap years (366 days) in multi-year degradation calculations. When OFF, all years are treated as 365 days.—
20LeTIDToggle—Enable Light and Elevated Temperature Induced Degradation modeling. When ON, applies additional degradation in early years that recovers over time, typical of PERC cells.—
21LeTID RatesTable%Year-by-year LeTID degradation rates. Typically shows elevated degradation in Years 1-3 followed by recovery. Values are editable for each year.—
22Add More YearsButton—Extends the LeTID Rates table with additional years beyond the default 25-year period.—
23Apply LeTID DefaultsButton—Populates the LeTID Rates table with default values based on typical PERC cell degradation and recovery curves.—

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Saving Changes

Click Save + Close Simulation Settings to save all configuration changes and return to the prediction. Click Save Progress to save without closing. Click Cancel to close without saving.