Home-battery brochures, in the Netherlands as elsewhere, lead with two numbers: capacity (kWh) and price (€). Both are necessary. Neither is sufficient. The honest break-even model for a residential battery requires four numbers, three of which the brochure does not contain. This piece is the worksheet — walked through with the figures of a typical 2026 Dutch household — and a frank statement of when the answer is no.
The four numbers
A battery's value, per cycle, is the spread between the price at which you fill it and the price at which you discharge it. Over a year it is the spread times the cycle count times the round-trip efficiency, minus the cost spread over the warranted cycles. Written out:
- Δp — the average daily spread between your cheapest charge window and your most expensive discharge window. This is the number the brochure cannot give you, because it depends on your contract and your discipline. On a dynamic contract in 2025, the daily peak-to-trough spread averaged around €0.22/kWh in the Dutch zone, with high-variance days reaching €0.40 and low-variance days under €0.05. On a fixed-tariff contract with no day/night split, Δp is zero and the battery loses money.
- N — the number of full-cycle-equivalents per year. A 5 kWh battery that discharges 3 kWh and recharges 3 kWh every day completes 0.6 cycles/day, or roughly 220 cycle-equivalents per year. On a household with solar surplus to absorb, the figure is more like 280.
- η — round-trip efficiency. Modern LFP residential batteries deliver between 0.88 and 0.92, after inverter losses. We use 0.90 below.
- C / L — the cost of the battery, divided by the cycles it is warranted to deliver. A €3,200 5 kWh battery warranted to 6,000 cycles costs €0.107 per delivered kWh of cycle capacity, or €0.535 per full-cycle of the 5 kWh pack.
The example, fully numbered
A household with a 4.5 kWp solar array, an 8,000 kWh annual import on a dynamic contract, and a habit of charging the EV at midday. They install a 5 kWh battery for €3,200, warranted to 6,000 cycles.
- Δp (12-month observed average on their contract): €0.21/kWh
- N (full-cycle-equivalents, mixed solar absorption and arbitrage): 260/year
- η: 0.90
- C / L: €3,200 / 6,000 = €0.533 per full cycle of 5 kWh
Annual gross saving from arbitrage:
5 kWh × €0.21/kWh × 260 cycles × 0.90 = €246/year
Annual amortised cost:
€0.533 × 260 cycles = €139/year
Net annual contribution: €107/year. Payback against the €3,200 capital outlay: roughly 30 years — well beyond the warranty.
This is not the brochure number. This is the honest one. For the typical Dutch household on a dynamic contract today, with today's spreads and today's hardware prices, a battery sized for energy arbitrage alone does not pay for itself.
Where the answer flips
The arithmetic above shifts under three conditions, in increasing order of likelihood:
- Spreads widen. Forward curves for the Dutch zone in 2027–2030 suggest Δp of €0.30–€0.38/kWh as more inflexible gas capacity retires and solar penetration deepens. At €0.35, the same battery yields €410/year gross, €271/year net, payback under twelve years.
- Saldering ends in 2027. A household with solar exports that no longer cancel one-for-one suddenly has 1,500–2,500 kWh per year of "free" charging energy, valued at the gap between the feed-in tariff (€0.07) and the household's own import price (€0.30) — a per-kWh saving of €0.23 on charging alone, before any discharge arbitrage. The figure for a 4.5 kWp household shifts from €107/year to roughly €425/year, and payback falls under nine years.
- The capacity tariff rises. Some Dutch grid operators are pricing in a household kW-peak charge from 2028. A battery that shaves the household's monthly peak by 2 kW, at €1.50/kW/month, contributes €36/year on top, and the case improves further.
What about backup?
Most Dutch residential batteries are not configured for islanded backup; they pass through the grid and shut down with it. Customers who specifically want power during a grid outage need either a different inverter or a different product entirely, with a meaningful (€800–€1,500) cost premium. The backup question is real, but it is a separate purchase from the arbitrage question — and the case is sentimental more than financial in a country with 99.99 per cent grid availability.
The honest summary
Today: a battery on a fixed contract loses money, slowly. A battery on a dynamic contract, with no solar, roughly breaks even over its warranted life. A battery on a dynamic contract with solar and after saldering ends pays back inside its warranty, and the closer you live to a household that uses electricity flexibly, the better the case looks.
The wizard above runs the four numbers for your contract and consumption shape against the prevailing spreads in each supplier's last twelve months of tariff data. It returns a single line — net annual contribution, in euros, with sign — and that is the figure that should drive the decision.
