Shape Factor
Capture Price ÷ Baseload Price
What is it?
The Shape Factor (also called "capture ratio" or "profile factor") is the ratio of a technology's capture price to the baseload average price. It quantifies how much value a technology extracts from the market relative to flat 24/7 generation.
Formula
Example:
If wind captures £45/MWh and baseload average is £50/MWh:
Shape Factor = 45 ÷ 50 = 0.90 (or 90%)
How to Interpret
The technology generates disproportionately when prices are low. Common for wind (0.85-0.95) and solar (0.80-0.90) due to cannibalization.
Generation profile perfectly matches the average price. Theoretical for a plant that runs at constant output 24/7 (like nuclear baseload).
The technology generates more when prices are high. Possible for peaking plants, storage, and demand-side response.
Typical Values (UK)
| Technology | Shape Factor | Notes |
|---|---|---|
| Onshore Wind | 0.88 - 0.95 | Higher in winter, lower in summer |
| Offshore Wind | 0.90 - 0.97 | Better profile than onshore |
| Solar PV | 0.80 - 0.92 | Lower due to midday concentration |
| Nuclear | ~1.00 | Flat baseload profile |
| Battery Storage | 1.20 - 1.50 | Arbitrages price peaks |
Impact on PPAs
Shape factor directly impacts PPA economics:
A wind PPA priced at £50/MWh with a 0.90 shape factor means the generator effectively earns £45/MWh on average. This discount is typically negotiated upfront or passed through in the settlement calculation.
Future Trend
As renewable penetration increases, shape factors are expected to decline further. More wind and solar capacity means more price suppression during high-output periods.
Aurora Energy Research projects UK wind shape factors could fall to 0.70-0.80 by 2030 without significant storage or flexibility investment.
API Endpoint
GET /uk/analytics/capture-price/{year}/{month}Returns shape factors alongside capture prices.
{
"wind": {
"capture_price": 48.50,
"shape_factor": 0.91
},
"solar": {
"capture_price": 45.30,
"shape_factor": 0.85
}
}