Aurora Sales vs. Design Mode: Solar Simulation Accuracy Comparison

Definition

Aurora Solar provides two simulation modes: Sales Mode (fast, ±5–8% accuracy, for customer conversations) and Design Mode (NREL SAM-driven, ±3–5%, for permit-stage engineering). Choose based on project stage.

Key Takeaways

Aurora Sales Mode: fast, simplified loss factors, customer-facing.
Aurora Design Mode: NREL SAM-driven, granular, permit-stage.
Use Sales Mode for proposals; Design Mode for final design.
Sales Mode accuracy ±5–8%; Design Mode ±3–5%.

Why Aurora Splits the Workflow Into Two Modes

Aurora built Sales Mode and Design Mode around two different jobs that happen at two different points in a project’s life. Early on, a sales rep needs a production estimate and a proposal fast enough to close a deal on a first call — accuracy within ±5–8% is acceptable because the customer is comparing options, not signing off on a stamped engineering package. Once a project is under contract, the same site model needs to hold up to permit reviewers and financiers, so Aurora runs it through SAM — NREL’s System Advisor Model — with finer loss granularity to tighten the estimate to ±3–5%.

What Changes Under the Hood

The two modes don’t just apply a different rounding rule; Design Mode recalculates the same roof and shading model with more loss factors broken out individually — soiling, module mismatch, wiring, inverter clipping, and temperature derate — rather than folding them into one blanket assumption the way Sales Mode does. Both modes typically draw from the same underlying irradiance dataset (for US projects, this is usually NSRDB/TMY3 data), so the accuracy gap comes from how finely each mode processes that data, not from a different weather source.

A Simple Illustration

Take a straightforward residential roof with one section of afternoon tree shading. In Sales Mode, Aurora applies a simplified shading and loss factor to produce an annual production number quickly enough to show the homeowner on the spot. Re-running the identical layout in Design Mode — same roof, same array, same shading obstruction — pushes that estimate through NREL SAM’s more granular hourly loss modeling, which can nudge the annual yield figure by a few percentage points once the finer-grained shading and derate calculations are applied. That shift is exactly why permit-stage and financing documents should be built from Design Mode output rather than the original sales estimate.

Aurora’s dual-mode workflow is one reason it remains a common pick for US residential and light-commercial teams, though plenty of installers weigh it against alternatives before committing — see our comparisons in Aurora vs HelioScope: 2026 Head-to-Head for Installers and Aurora Solar Alternatives for US Installers in 2026. For projects where even Design Mode’s SAM-driven output isn’t granular enough — think bifacial gain calculations or complex row-to-row shading on a commercial array — engineering teams often pair Aurora’s site model with a dedicated yield-simulation pass, a workflow covered in Advanced PVsyst Analysis: How Accurate Yield Predictions Save Millions. Teams still deciding whether Aurora’s two-mode approach fits their stack can also see how it stacks up against alternatives in SurgePV’s Aurora Solar comparison.

Frequently Asked Questions

6 commonly searched questions about Aurora Sales Mode vs Design Mode.

What's the actual difference between Aurora Sales Mode and Design Mode?

Sales Mode uses simplified loss factors and a faster rendering pipeline so it can generate a proposal-ready estimate in seconds, at roughly ±5–8% accuracy. Design Mode runs the same shading and layout inputs through NREL's System Advisor Model (SAM) engine, applying granular losses — module mismatch, wiring, soiling, temperature derate — for a tighter ±3–5% accuracy band suited to permit-stage engineering.

When should a designer switch from Sales Mode to Design Mode?

Switch once the deal moves past the initial customer conversation and into contract or permit submission. Sales Mode is fine for a same-call proposal; any output that will support a stamped permit set, an interconnection application, or a financial commitment should be re-run in Design Mode.

Does Sales Mode use the same weather and irradiance data as Design Mode?

Both modes pull from the same underlying site and weather inputs (typically NSRDB/TMY3 data for US projects), but Design Mode's SAM engine processes that data with more granular hourly loss modeling, which is the main source of the accuracy gap between the two modes.

Can I submit a Sales Mode production estimate for a permit or utility interconnection application?

No. Sales Mode's ±5–8% accuracy is intended for customer-facing proposals, not for documents an AHJ or utility will scrutinize. Permit and interconnection packages should use Design Mode output, since it reflects NREL SAM's more detailed loss and shading calculations.

Is Design Mode slower to run than Sales Mode?

Yes. Because Design Mode recalculates shading and losses at a finer granularity through the SAM engine, it takes longer per run than Sales Mode's quick estimate — a reasonable trade-off once the extra accuracy is worth the wait, such as at permit or final-design stage.

Do Sales Mode and Design Mode ever produce meaningfully different production numbers for the same roof?

They can, especially on roofs with partial shading, mixed orientations, or non-standard racking. Sales Mode's simplified loss factors tend to smooth over these details, while Design Mode's finer-grained SAM modeling captures them — which is exactly why the two modes carry different accuracy bands.