1. The header — who you're paying
Every Spanish bill (factura de la luz) shows two companies: your commercialiser (whom you pay — Iberdrola, Endesa, TotalEnergies, Naturgy) and your distributor (the local grid operator, e.g. i-DE on the Costa Blanca). You can change commercialiser; the distributor is fixed.
2. CUPS code — your villa's unique ID
The CUPS (Código Universal del Punto de Suministro) is a 20–22 character code identifying your supply point. You'll need it for any provider switch, solar registration or subsidy application — keep it handy.
3. Potencia contratada — the silent monthly cost
This is the maximum power (in kW) your home can draw at any moment. You pay for it every single day, used or not. Most villas have 5.75–14.49 kW contracted. Since 2021 you have two values: peak (P1) and off-peak (P2). Common villa mistake: contracting 9.2 kW or more 'just in case' and overpaying €15–€40/month forever.
4. Energy consumed — the kWh section
Your actual usage. Since 2021 most tariffs split the day into three periods: P1 Peak (10–14h, 18–22h weekdays — most expensive), P2 Mid (8–10h, 14–18h, 22–24h weekdays — medium) and P3 Off-peak (00–8h weekdays + all weekends — cheapest). Solar produces most during P1/P2 — exactly when grid power is most expensive.
5. Taxes and surcharges
Impuesto sobre la Electricidad (around 5.11%) and IVA (VAT, typically 21%). Both apply to power + energy + meter rental. Lower the bill, lower the taxes.
6. Spot savings in 5 minutes
Check peak demand vs. contracted power — if you never come close, lower it. Compare P1 vs. P3 — if most usage is in P1/P2, solar pays back fast. Total annual kWh ÷ 12 = your monthly average — that's how solar is sized.