Methodology: sources, prices and reference calculations
Updated
Every figure needs its date, source and assumptions. We distinguish official rules, published offers, modelled results and measurements. None of those categories automatically substitutes for another.
Sources and check dates
We check support against the relevant programme, grid connection with the distributor and sharing with OKTE. For equipment, the exact model and revision documentation matters. A manufacturer's claim about its own product is not an independent test.
A source-check date records when the underlying material was reviewed; it does not guarantee that nothing has changed. A price list or programme may have its own separate date. Confirm current conditions and availability before ordering.
The reference calculation
The calculator uses 81 saved hourly scenarios: three reference cities, three annual consumption levels, three assumed demand profiles and three usable battery capacities. The base installation is 5 kWp facing south at 35°, with PVGIS weather for 2023. The source version is PVGIS-2023 / hourly model dated 21 October 2026.
Generation, direct use, battery delivery, imports, exports and losses are shown separately. Demand profiles are assumptions, rather than measurements of your home. Selecting a city does not forecast a particular roof; the model does not know your shading or interval demand.
Financial equations and omissions
Avoided-import value equals reduced grid imports multiplied by the entered import price. Export value equals exported energy multiplied by the entered export price, which can be negative. Annual benefit equals avoided-import value plus export value, less additional annual fees and operating costs.
Net investment equals investment less the entered support. Simple payback compares investment with a positive annual benefit. Support is a user input, not an eligibility decision, and existing fixed supply charges are not automatically counted as savings.
Simple payback excludes discounting, financing, price changes, degradation and future equipment replacement. No positive payback is reported when the benefit is non-positive. Hourly scenarios do not replace quarter-hour sharing evaluation. Virtual batteries are not physical storage, and the model establishes neither backup capability nor individual capacity-exceedance fees.
Prices, directories and comparisons
Compare the same scope: power, exact equipment, usable storage, installation, inspection, connection, service, VAT and support. A single public offer is not a Slovak market average. Packages with similar power are not necessarily directly comparable.
For companies, we distinguish a registered address, a register entry and a documented project. A district address does not confirm service throughout the region. SIEA registration is not a quality rating, and a supplier reference is not an independently audited household result.
Recommendations describe suitability and limits. We do not assign invented stars or absolute market rankings without consistent test conditions and transparent evidence.
Corrections and commercial independence
Report an error through contact with specific supporting material. For a substantive correction, we update the affected content and the date according to the scope reviewed.
Future paid links or placements must be visibly identified. Commercial funding must not change editorial ordering. The How we earn page explains the current state.