Quick Answer
First separate imported energy, contracted power, services and export compensation on the bill. Match its dates to the meter readings and check whether compensation is active. A high generation figure alone does not show how much grid electricity your home avoided buying.
Check these five things before buying more equipment
Collect your bill, distributor import/export readings and inverter production for exactly the same dates. Compare imported kWh per day across similar seasons and occupancy, rather than comparing only the final euro amount. Check whether readings are actual or estimated and whether this bill includes earlier adjustments.
- Little or no recorded generation: check monitoring connectivity and fault messages. Send dated screenshots to the installer; an offline app alone does not prove generation stopped.
- Normal generation, high imports: compare hourly usage with production. Evening cooling, water heating and EV charging may explain the difference.
- Metered exports, no bill credit: request registration evidence from the installer, self-consumption status from the distributor and an activation date from the supplier.
- Fewer imported kWh, similar bill total: compare unit prices, billing days, power charges, services, meter rent and taxes.
- A full battery while the home imports: ask the installer to check reserves, discharge limits, schedules and metering configuration.
Use our missing export credits guide for the administrative checks. Do not open electrical enclosures. Burning smells, visible damage or repeated trips need a qualified electrician.
Worked example: why the whole bill does not halve
Illustrative arithmetic, not a customer bill or a current tariff offer. Assume a 30-day period and an import price of EUR 0.20/kWh. Before solar, 400 imported kWh cost EUR 80. After solar, 250 imported kWh cost EUR 50. If 200 exported kWh receive EUR 0.05/kWh, the EUR 10 credit leaves an energy subtotal of EUR 40.
The energy subtotal has halved, but power charges, services, rent and taxes still need to be calculated. If the post-solar import price instead rises to EUR 0.28/kWh, those same imports cost EUR 70, leaving EUR 60 after the credit. That difference comes from the tariff, not the panels.
Understanding post-solar bill disappointment
It is a common scenario in Spain: homeowners invest thousands of euros in solar panels, only to receive their first few bills and see minimal savings.
Possible causes include equipment faults, changes in consumption, administrative delays, fixed charges and tariff prices. Check the evidence before deciding whether the installer or supplier needs to act.
1. Export compensation (compensación) is not active yet
Your system will start generating power immediately, but you cannot receive bill credits for exported surplus energy until the system is officially registered (legalised) and your utility supplier activates your export tariff.
Ask the installer for the applicable commissioning and registration evidence, then confirm distributor status and supplier activation. Timing varies by case. Keep a written reference for missing records and ask whether a billing correction applies; do not assume all pre-activation exports will be credited retrospectively.
For qualifying low-voltage installations up to 100 kW, Article 16 bis of Real Decreto 244/2019 sets an activation-delay framework measured from the distributor receiving the necessary documents, not the installation date. Ask whether its delay discount applies; eligibility depends on the cause and documentation of the delay.
2. Contracted power (potencia) is set too high
In Spain, you pay a fixed daily standing charge based on your contracted power capacity (potencia contratada, measured in kW). If your contracted power is set to 8.8 kW, you pay for that capacity every month even if your solar panels cover your entire energy usage.
Review maximum demand in both contracted-power periods, including winter evenings and times when a battery is empty. Panel capacity in kWp does not establish a safe reduction in grid capacity in kW. Obtain advice based on your demand records before changing capacity.
3. You are on the wrong electricity tariff
Compare the complete annual cost under your current contract and alternatives. You do not necessarily need to switch supplier or buy a product labelled a solar tariff. A higher export rate can be outweighed by higher import prices or monthly fees.
For electricity tariff switching and post-install bill optimisation, we work alongside weSwitchSpain to find the best tariff matching your new solar generation profile.
Illustrative bill layout, not a customer bill or a current supplier offer.
4. Sizing and consumption misalignment
If your baseline consumption occurs entirely in the evenings (e.g., running air conditioning, pool heating, or charging an electric vehicle overnight) and you do not have a physical battery, you will still import a large amount of expensive energy from the grid. Try shifting your heavy appliance usage (washing machines, dishwashers, pool pumps) into peak sunshine hours.