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Hoe wij rekenen — en wat we níét publiceren

Iedere aanname op deze pagina wordt rechtstreeks uit de code gelezen, niet met de hand overgetypt. Verandert de rekenmachine, dan verandert deze pagina mee. Zo kan hij niet stiekem gaan liegen. Ook als JSON: /api/assumptions.

Wat we weigeren te publiceren

Any comparison built on a tariff we have not verified against the provider's own sheet — the dynamic-vs-fixed panel stays hidden until a real fixed contract is verified.
A payback number when the battery does not repay within its lifetime. We say 'never' instead.

De batterij — de kosten die anderen vergeten

Rendement (heen-en-terug)	88%
What real INSTALLED systems achieve with the hybrid inverter in the loop (~85-88%). Datasheet cells look like 95%+; quoting that is how a calculator quietly gains a few percent.
Standby-verlies	10 W continu
The battery + inverter draw 10.0 W continuously = ~88 kWh/yr of pure loss, whether or not they ever cycle. We charge it to the battery case only. It is why a battery can leave you WORSE off on a low-spread day. Most calculators omit this entirely.
Max. cycli per dag	2
Slijtagekosten in dispatch	0
Deliberately 0 in the dispatch: the capital cost is accounted for in the payback calculation instead. Charging both would double-count.

Terugverdientijd

Capaciteitsverlies	2.0% per jaar
Aangenomen levensduur	15 jaar
Cumulative savings with capacity fade until they repay the price. The naive price / first-year-savings pretends savings never decline. If it does not repay within the lifetime we say 'never' rather than quoting a meaningless 27-year 'payback'.

Prijzen — energy-charts.info (Fraunhofer ISE)

Licentie CC BY 4.0 · hourly before 2025-10-01, 15-minute after · stored in UTC; grouped into Europe/Amsterdam local days (DST-correct: 23h/25h days)

Zone	Van	Tot	Intervallen	Gaten
DE-LU	2018-10-01	2026-07-09	88.440	geen
NL	2016-01-01	2026-07-09	112.535	geen

De berekening

Linear program per day (scipy HiGHS), grid-side kWh accounting.

Vooruitblik: Perfect within-day foresight = an UPPER BOUND. Day-ahead prices genuinely are known a day ahead, so that part is realistic; your load and solar are not, so real results will be lower.

SoC bounds via cumulative constraints; SoC returns to its start each day
power cap on charge and discharge
max cycles/day cap
no grid passthrough: export <= solar + discharge (you cannot resell grid imports)

Zon & verbruik

Zon (PVGIS v5.3 (EU JRC), SARAH3 radiation): For price years up to 2023 we align the ACTUAL solar year to the actual prices. Later years fall back to a typical meteorological year, because PVGIS does not have them yet. Shading, inverter clipping and panel degradation are not modelled.

Verbruik: This is the biggest per-household error source: your house is not average. Upload your own smart-meter (P1) export and we use your real metered consumption instead — it typically moves the answer by tens of percent.

Leverancierstarieven — per veld, met hoe zeker we zijn

Geldig vanaf 2026-01-01 · energiebelasting 10.88 ct/kWh · btw 21% · saldering nu actief. Salderingsmodel: Volumetric and time-blind annual netting (that is what saldering actually is), with the surplus above consumption paid at feed-in.

Leverancier	Opslag	Vast/mnd	Terugleverkosten	Zekerheid (opslag / vast / teruglever)	Publiceerbaar
ANWB Energie	1.49 ct/kWh	€8.50	0.00 ct/kWh	geverifieerd geverifieerd geverifieerd	ja
Budget Energie	1.68 ct/kWh	€5.99	0.00 ct/kWh	deels deels geverifieerd	ja
NextEnergy	1.81 ct/kWh	€5.99	0.00 ct/kWh	onbevestigd geverifieerd geverifieerd	ja
Tibber	1.50 ct/kWh	€5.99	2.48 ct/kWh	onbevestigd deels geverifieerd	ja
Zonneplan	1.65 ct/kWh	€6.25	-2.00 ct/kWh	geverifieerd geverifieerd geverifieerd	ja
Eneco Dynamisch	1.99 ct/kWh	€7.00	2.92 ct/kWh	onbevestigd deels deels	nee
Fixed (typical 2026)	0.00 ct/kWh	€5.95	0.00 ct/kWh	unknown unknown unknown	nee
Frank Energie	1.82 ct/kWh	€4.99	1.82 ct/kWh	deels onbevestigd onbevestigd	nee
Vandebron	1.83 ct/kWh	€6.99	1.36 ct/kWh	geverifieerd geverifieerd onbevestigd	nee

"Publiceerbaar = nee" betekent dat een veld nog niet tegen het eigen tarievenblad van de leverancier is geverifieerd. We tonen die leverancier wel, maar zeggen erbij dat het cijfer indicatief is — en we bouwen er geen vergelijking op.

Waar wij onzeker zijn

Geen enkele rekentool is exact. Dit is de eerlijke lijst van waar de onze tekortschiet — de dingen die een verkoper je niet vertelt:

We have never validated against a real household's measured bill. Our verdict is triangulated against independent studies (CE Delft 6.5-22yr, jeroen 10-22yr, Consumentenbond 'often not within the ~15-yr life') and a test fails if we ever drift faster than any of them.
Perfect within-day foresight on load and solar makes results an upper bound.
Typical-year solar for price years PVGIS does not cover yet; no shading or inverter clipping.
Some provider fields (notably the per-kWh markup) are not published by the providers themselves and rest on comparison sites — flagged per field.
§14a Modul 3 tiers are applied year-round, though some German operators only run time-variable pricing in winter quarters.

Aannames gelezen op referentiedatum 2026-07-01. ← terug naar de rekentool