Key points
- PVGIS gives a good starting point for generation modelling
- Self-consumption is the most sensitive input to model
- Layer SEG or PPA tariffs on the export kWh to get revenue
- Always model low/base/high scenarios before committing
Model your generation
Use PVGIS or your installer's shading study to get a monthly kWh profile. Real-world output typically comes in 5–10% below theoretical.
Estimate self-consumption
Half-hourly consumption data (or a load survey) determines how much of your generation you'll actually use on-site. This is the single most sensitive input.
Price the export
Apply your SEG or PPA tariff to the exported kWh. Add any aggregator uplift if you're using one.
Sensitivity analysis
Run three scenarios — low, base, high — for both generation and tariff. Investment decisions should look sensible across all three.
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