Performance simulation settings control the defaults Aurora uses when calculating energy production for your designs. These defaults apply in Sales Mode and can be adjusted on a per-design basis in Design Mode.
To access these settings:
- Go to Settings in the left navigation.
- Under Projects and designs, select Performance simulations.
- Click Edit to make changes, then click Save.
In this article:
General
General settings apply across all simulation engines.
- Simulation — Choose the default simulation engine: Auto, Aurora, or PVWatts. Auto defaults to the Aurora engine when panels are connected to an inverter; it falls back to PVWatts for Aurora AI-generated designs, which don't require strung systems.
- Shading engine — When enabled, Aurora calculates incident irradiance on each module, accounting for shading from nearby trees, buildings, and roof obstructions.
- Use LIDAR shading — When enabled, Aurora uses available LiDAR data to determine shading profiles. Learn more about LIDAR shading.
- Use horizon shading — When enabled, Aurora accounts for shading caused by distant terrain features such as hills and mountains. Default: On. Learn more about Horizon Shading.
- Use module's light-induced degradation and annual degradation data, if available — When enabled, Aurora uses manufacturer-supplied LID and annual degradation values for the module in the design (if available in the database), rather than the default system loss values. Default: On.
Aurora simulation settings
These settings apply when the Aurora simulation engine is active.
- Irradiance model — The irradiance model used in the Aurora simulation engine. Options: Perez (default), Hay Davies, or Reindl. Learn more about Aurora's Simulation Engine.
- Inverter clipping — When enabled, Aurora reports how much energy is lost when DC input power exceeds the inverter's AC power rating. Learn more about Inverter Clipping. Default: On.
- Use sub-module simulation if available — When enabled, Aurora models every cell string in the design for the highest available simulation accuracy. Only supported for modules where Aurora has verified the internal cell string configuration with the manufacturer, and for compatible inverters. Learn more about Submodule Simulation.
- Weather dataset — The weather dataset Aurora uses for simulation.
PVWatts settings
These settings apply when the PVWatts simulation engine is active. PVWatts does not require inverters or a strung system. Learn more about PVWatts.
- Default inverter efficiency — The default inverter efficiency percentage used in PVWatts simulations.
- Default DC:AC ratio — The default DC-to-AC ratio used in PVWatts simulations. Learn more about choosing the right size solar inverter.
- Weather dataset — The weather dataset used with PVWatts.
System losses
System losses account for the difference between a module's rated power and the actual power output of a complete installed system. These default values apply to all new projects and can be adjusted per design in Design Mode. Learn more about System Losses.
The estimated total loss is calculated from the sum of all individual loss factors:
- Module nameplate rating — Accounts for the tolerance between a module's rated and actual output.
- Mismatch — Accounts for performance differences between modules in the same string.
- Connections — Accounts for resistive losses at electrical connections.
- Light-induced degradation (LID) — Accounts for the initial output drop that occurs when crystalline silicon modules are first exposed to sunlight.
- Wiring — Accounts for resistive losses in DC and AC wiring.
- Soiling — Accounts for output reduction due to dust, dirt, and debris on module surfaces.
- Availability — Accounts for downtime due to scheduled maintenance and system outages.
- Shading — Dynamic; calculated from the site model and shading analysis. Shown as n/a until a design is created.
- Age — Accounts for long-term module degradation beyond the first year.
- Snow — Accounts for output reduction due to snow coverage. If you install in snowy climates, review guidance on monthly snow loss values.
- Other — A catch-all for any additional system losses not captured by the above categories.
Estimated total loss — The sum of all individual system loss percentages. Displayed as a read-only total for reference.
📝 Note: If you install in areas with regular snowfall, set an appropriate Snow loss value to ensure your production estimates accurately reflect local conditions.
Related articles