Energy purchasing

The purchasing function inside an Iberian retailer or aggregator sits at the intersection of forecasting, execution and settlement. A book that is well forecast but poorly executed loses margin to spread; a book that is well executed but poorly settled loses margin to invoice disputes and unrecovered counterparty positions. The function works only when all three layers run together.

This pillar covers five deliverables. Each can be scoped as a standalone engagement or combined into a programme.

1. Demand forecasting

A working demand forecast is the foundation of every purchasing decision. Most retailers under 500 GWh are forecasting with a mix of seasonal averages and the previous-week shape, which is sufficient for a stable portfolio but materially under-prices the cost of a high-PV book on an unusually cloudy day or a high-air-conditioning book on a heatwave.

Deliverable scope:

• Build of an hourly demand forecast covering the book's customer mix, with weather, calendar and tariff shape inputs
• Calibration against the previous 24 months of metered data
• Integration with the purchasing desk's execution workflow
• Ongoing monthly recalibration and exception monitoring

Typical engagement: 6 to 10 weeks of build, with optional ongoing calibration retainer. Sits well with the analytics and dashboards workstream.

Related reading: Demand forecasting in an Iberian retail context.

2. Purchasing in different markets (OMIE, GdO, bilateral)

The retailer's purchasing universe is broader than OMIE day-ahead. A working purchasing function covers:

• OMIE day-ahead and MIBEL intraday auctions
• MEFF futures for hedging the book out 6 to 24 months
• Bilateral PPAs with renewable generators (where the book has a green-tariff offering)
• Guarantees of origin (GdOs) on the secondary market
• Cross-border interconnection where the retail offer includes France

Deliverable scope:

• Execution strategy across the day-ahead, intraday and futures markets, calibrated to the book's risk appetite
• Bilateral PPA evaluation and execution support
• GdO procurement strategy (covered in more depth in workstream 3 below)
• Counterparty selection and onboarding

Typical engagement: 4 to 8 weeks of strategy and process build, with optional execution-desk support for retailers that prefer a managed-service model.

Related reading: Operating against OMIE, Purchasing in MIBEL intraday markets.

3. Calculation and monitoring of guarantees

Trading guarantees are one of the largest line items on the retailer's working-capital position and one of the most operationally fragile. A miscalculation against OMIE or MEFF results in a margin call within 24 hours; a missed margin call results in suspension from the market. Most retailers under 1 TWh are tracking their guarantee position in a spreadsheet maintained by one person, with no formal escalation procedure.

Deliverable scope:

• Build of a guarantee monitoring engine covering OMIE, MEFF, REE and any cross-border CCP positions
• Daily mark-to-market reconciliation against counterparty reports
• Working-capital optimisation across guarantee instruments (cash, bank guarantee, parent company guarantee)
• Escalation playbook for margin events and counterparty default

Typical engagement: 8 to 12 weeks of build, with recommended monthly review as part of the regulatory monitoring work.

Related reading: Calculating and monitoring trading guarantees.

4. GdO procurement and registry management

Guarantees of origin are now a material commercial input for any retailer selling a green-tariff product into the Iberian market. The supply is thinner than the demand, the secondary market is fragmented, and the registry operations (CNMC for Spain, DGEG for Portugal) have process requirements that are easy to miss.

Deliverable scope:

• Annual GdO requirement forecast aligned to the green tariff customer book
• Procurement strategy across the secondary market, long-term offtake contracts and corporate PPAs with renewable IPPs
• Registry operations: cancellation, transfer, expiry monitoring
• Audit trail for the regulator and for the retailer's marketing claims

Typical engagement: 6 to 8 weeks, with optional ongoing registry-management retainer.

Related reading: GdO procurement and registry management.

5. Billing management against DSO, REE, OMIE and MEFF

The retailer receives between five and twelve material invoices a month from the system operators, the DSOs and the market operators. Reconciling these against the internal book is where most retailers find their largest month-on-month variances, and where most retailers have the weakest operational discipline.

Deliverable scope:

• Process design for the invoice reconciliation cycle (DSO ATR settlements, REE balancing settlements, OMIE day-ahead and intraday settlements, MEFF clearing reports)
• Build of a reconciliation engine integrating the retailer's internal book with the invoice feeds
• Exception handling playbook for common dispute types (DSO meter reading disputes, REE balancing curve disputes, OMIE clearing-price disputes)
• Monthly close discipline and variance reporting

Typical engagement: 8 to 12 weeks of build, with strongly recommended ongoing managed support given the operational weight.

Related reading: Billing management: DSO, REE, OMIE and MEFF.

How this pillar typically engages

For most retailers, the right starting point is the guarantee monitoring workstream or the billing reconciliation workstream. These have the largest margin-leak exposure and the clearest payback. The forecasting and execution workstreams pay back over a longer horizon and benefit from being run after the back-office foundation is solid.

The diagnostic engagement takes two weeks and gives a defensible picture of the priority order.

AI-led products under this pillar

The five deliverables above are also available as AI-led products that ship as working systems rather than engagements:

• Forecast. AI-led hourly demand forecasting.
• Execute. Agent-mediated execution across OMIE, MIBEL, MEFF and GdO.
• Margin. Real-time guarantee monitoring.
• Reconcile. AI-led invoice reconciliation.

Read the purchasing products page →

Related pillars

• Operational management: switching, ATR, back office, customer service, regulatory submissions.
• Analysis and pricing: pricing design, market reporting, analytics, regulatory monitoring.