Tarun Bulchandani
← All energy insights
by Tarun Bulchandani

Switching and ATR with the Iberian DSOs

Switching customers in and out of an Iberian retail book runs on the SIPS data exchange with the eight major Spanish DSOs and Portuguese e-Redes. The formats are documented; the operational realities are less so. A note on the patterns that determine whether a retailer's net position grows or quietly leaks.

Every customer change of supplier in the Iberian retail market is processed through the SIPS data exchange. The retailer initiates a switching request, the DSO validates it, the customer's previous supplier is notified, and the change becomes effective on the next billing cycle. The mechanism is well-documented in the ITC/2724/2009 framework and updated through the more recent CNMC resolutions.

The operational realities of running this at scale are where retailers find their largest unrecognised losses.

The eight Spanish DSOs

The retailer operating nationally exchanges with:

  • e-distribución (Endesa)
  • i-DE (Iberdrola)
  • UFD (Naturgy)
  • Viesgo Distribución
  • Hidrocantábrico (EDP)
  • Plus the smaller regional DSOs: Bassols, Solanell, Estabanell, Eléctrica del Maestrazgo, and others

Each DSO has its own implementation of the SIPS message format. They are nominally identical; in practice each has minor variations in how it validates incoming requests, how it formats outgoing responses, and how quickly it processes exceptions. A retailer with a national book runs eight independent integrations.

The Portuguese exchange

Portugal runs the equivalent exchange with e-Redes (the national DSO operated by E-Redes Distribuição). The format is documented; the cadence is similar to the Spanish exchange. The cross-border retailer with business in both markets runs two separate sets of integrations.

What goes wrong

Five patterns drive most of the operational losses.

CUPS mismatches. The customer's CUPS code (the unique identifier of the supply point) is the primary key for the switching request. A mistyped CUPS, a CUPS that has been updated in the DSO registry but not in the retailer's system, or a CUPS with an out-of-date status results in a rejected switching request. The customer thinks they have switched; they have not.

Postal code disputes. The DSO validates the postal code against its registry. A new customer at an address with a recently updated postal code (street renaming, new development) generates a rejection.

Tariff code mismatches. The customer applies for a tariff that does not match the DSO's record of the supply point's tariff eligibility. The switching request rejects.

P1-P6 period misclassifications. The supply point's time-of-use eligibility is recorded by the DSO. A retailer offering a time-of-use tariff against a supply point not registered for time-of-use generates a rejection.

Cancellation race conditions. A customer initiates a switch to retailer A, then changes their mind and initiates a switch to retailer B before A has processed the first switch. The SIPS framework specifies how this should resolve; the implementation across the eight DSOs is not perfectly uniform.

The aggregate effect of these patterns is that a typical national retailer has 1-3% of its monthly switching volume rejected for technical reasons. Of those, perhaps half are recovered through the exception process; the rest are quiet losses.

What a working switching operation covers

Six components.

  1. A validation layer that runs against each switching request before submission, checking CUPS, postal code, tariff eligibility and period classification against the latest DSO data.
  2. A submission discipline with retry logic for transient DSO failures and escalation for persistent ones.
  3. An exception handling workflow covering the common rejection reasons, with documented resolution paths and target SLAs.
  4. Monthly switching analytics covering gross add, gross loss, net position, time-in-switch and exception rate by DSO.
  5. Customer communication discipline. A customer whose switching request has been rejected should be notified within 48 hours, not left to discover the problem on the next bill from the previous supplier.
  6. A reconciliation against the ATR settlement invoices. The switching activity drives the underlying customer book; the ATR settlement invoices have to reconcile against it.

How this lands in operations

A retailer with weak switching operations is losing customers without seeing why and gaining customers it cannot bill. The operational damage shows up in two places: the gross-add to net-add ratio and the unrecovered ATR settlement variance.

For most retailers, switching operations is the single highest-impact workstream in the back office. The operational management pillar covers it as workstream 1.

Related: Back-office operations for Iberian retailers, Billing management: DSO, REE, OMIE and MEFF, Customer service operations in Iberian energy retail.