How the household report is calculated

From household inputs to product choices

1. Location uses PDOK/BAG evidence. A province or postcode area is a reference location, not a surveyed roof.
2. Measured household electricity takes priority. Total electricity includes direct solar use; known annual totals are not increased again for additional household members.
3. Historical 2023 PVGIS weather, system size and orientation create the solar profile. Supplied annual or complete monthly generation can calibrate it.
4. EV, heat-pump and other device use is marked as included, excluded or unknown. Included devices change timing rather than being counted twice. Circuit limits constrain charging and discharging.
5. Fixed contracts use a reference rate; variable contracts can use twelve monthly rates; dynamic contracts use hourly market prices with explicit supplier-cost assumptions.
6. Household supply and demand establish a brand-neutral solar-shifting requirement. All computable retail configurations are evaluated before selecting one main choice per brand and showing expansion alternatives.

Capacity, power and conversion losses

The physical reference uses the normalized knee of the annual solar-delivery curve, with scans ending at 15 and 30 kWh. It is a diagnostic sizing choice requiring household validation, rather than a claimed maximum economic marginal benefit.

Charge and discharge limits are applied independently. A 1.2 kW charging limit can absorb at most 1.2 kWh in one hour. Stored energy carries across days and the modeled reference year returns to a consistent inventory.

The default 85% round-trip efficiency is already in the simulation. Charge and discharge efficiency each equal √0.85. Do not divide the modeled capacity by 0.85 again. Product nominal capacity remains distinct from verified usable capacity, and hardware power assumes suitable installation.

The financial comparison

Annual savings compare a household without a battery against the same household and tariff with each configuration. Reduced grid purchases, lost export compensation, export fees, grid-charging costs and conversion losses are accounted for together.

Dynamic and dual-rate optimization uses a 48-hour ideal forecast, executing 24 hours at a time. It includes low-price grid charging for later household use. Battery-to-grid trading income is excluded; actual control performance is not guaranteed.

Each configuration has its own catalogue price and investment calculation. Payback is the first crossing of cumulative net cash flow; ten-year net benefit subtracts initial investment. Policy periods and entered annual reductions are retained, including changed compensation treatment from 2030.

Unknown contract terms prevent a confirmed payback or ROI. Unquoted installation, accessory and operating costs remain unknown; a known-cost result is not a complete installed-cost quotation.

Sources and scenario assumptions

Weather and market prices use a 2023 reference year, not future forecasts. Dynamic prices are attributed to Energy-Charts / SMARD (CC BY 4.0). Reference defaults—zero supplier markup, zero export adjustment, €0.05/kWh minimum gross compensation and no base export fee—are editable assumptions, not supplier quotations or statutory rates.

The additional €0.15/kWh export fee is a stress-test assumption, shown alongside each product. It is not a universal charge. Tax inputs use the 2026 reference schedule; future tax rates are not guaranteed.

Product prices and availability are from the Solar Power Supply catalogue snapshot of 8 October 2026. Each report retains product and specification links; current stock, usable capacity, installation and a full quote need separate confirmation.

Dutch government: net-metering changes · Historical market-price source