Your system.
Your savings.

Fixed charges stay on the bill

The presets use 2026 EAC bill examples: €8.00 supply + €0.94 meter data management, plus VAT. That is €9.39 per two-month bill for the domestic sample (5% VAT), or €10.64 for the business sample (19% VAT). You can enter the amount from your own bill. Fixed charges are deducted before estimating kWh from the total bill, and remain payable after both current export offset and carried credit. One-off fees, arrears and late-payment interest are not treated as regular fixed charges.

Energy and system sizing

Consumption = (two-month bill − fixed charges) × 6 ÷ purchase tariff. Annual generation targets at least 110% of consumption, adjusted for roof orientation and rounded up to 0.5 kWp, minimum 2 kWp. Zero Export shows potential generation, with unused surplus curtailed. Seasonal profiles are illustrative; this is not an hourly simulation.

Savings and export offset

Realistic annual benefit = avoided electricity purchases + export credits actually applied to the six bills. Within each bill, the smaller of imported and exported kWh is offset at the selected rate, capped at the purchase tariff. Surplus export becomes next-bill credit at €0.10/kWh, converted once. Earlier credit reduces remaining energy charges, including transfer, after the current offset; any unused monetary balance is retained. It cannot offset fixed charges or produce a cash payout. Starting credit is zero; closing credit is excluded from current savings. Transfer is counted once. The theoretical model values all generation at the purchase tariff. Payback = budget ÷ annual benefit; 20-year benefit = 20 × annual benefit − budget, with the annual scenario held constant.

Battery storage and EV charging

Automatic sizing: 10 kWh below 8 kWp, 16 kWh from 8 kWp; manual options 10 / 16 / 24 / 32 kWh. Direct daytime solar use defaults to 45% of generation and can be changed above. Storage is calculated separately for an average day of each month: up to one cycle per day, 90% usable capacity and 90% round-trip efficiency. Only solar surplus after direct home and daytime EV use charges the battery; discharge covers remaining home demand, with a 95% monthly home-coverage ceiling. Capacity changes stored energy, imports, exports and financial results. Larger storage stops adding energy when surplus or remaining demand runs out. These are illustrative assumptions, not an hourly weather or equipment simulation. EV charging uses direct daytime surplus only; charging already in the bill is not added twice.

Costs and time horizon

Solar and storage use aggregated 2026 offers, including an assumed 19% VAT. The 24 kWh class includes 23.6 kWh models. Pricing covers 2–20 kWp; larger systems need an individual quote. EAC fees, structures and additional work are quoted separately. A complete EV budget needs the final charger and installation cost; enter 0 only if no additional cost applies. No maintenance costs are included. Tariffs and generation stay constant; degradation, replacements, finance and grants are excluded. Offset parameters define the company scenario and are confirmed for the property.