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Explore one transparent home-energy illustration
Adjust four broad inputs to compare a synthetic current annual cost with simplified solar and solar-plus-battery outcomes.
Illustration, not advice. This deterministic model is not a quote, engineering assessment, financial advice, or savings guarantee. It does not submit or store entered values.
Synthetic output
Illustrative annual costs
- Current
- €1,440
- With solar
- €900
- With solar + battery
- €720
Illustrative reduction: €540–€720 per year.
Selected illustration: solar + battery at €720 per year.
How the synthetic formula works
The model multiplies the monthly bill by 12 and rounds to the nearest €10. It caps the roof contribution at 35 m², then combines that factor with daytime use in a bounded solar-reduction heuristic. Selecting battery adds a smaller fixed adjustment, also bounded.
The formula is deterministic so the same inputs always produce the same illustration. It does not predict energy generation, system size, or financial return.
Deliberately excluded
- location-specific solar irradiation and shading
- equipment efficiency, condition, price, and installation cost
- electricity tariffs, export payments, and future price changes
- battery degradation, financing, payback, and electric-vehicle demand