V2G profit and battery-wear break-even calculator
Estimate whether selling power back from an EV battery (vehicle-to-grid, V2G) pays for the extra battery wear it causes, and find the export price you need just to break even.
Result
Estimated annual net profit
Margin per kWh exported
Break-even export price
Battery wear cost per kWh exported
How to use this tool
- Enter your battery's usable capacity in kWh, not its marketing total if the two differ.
- Enter what you pay per kWh to charge (for example an off-peak rate) and what you would be paid per kWh exported at peak times.
- Enter the replacement cost of the battery pack and how many full cycles you expect it to last, from the manufacturer's warranty or a battery-health figure.
- Enter how many full discharge cycles per year you expect to run for V2G, plus any fixed fee your aggregator or charger charges.
- Read the annual net profit. A negative figure means V2G loses money at these prices.
Assumptions
- Each V2G cycle discharges the full usable capacity. Shallower cycles earn less per cycle but wear the battery less, so treat the cycle count as full-equivalent cycles.
- Battery wear is linear: every kWh discharged costs the same. Real degradation depends on temperature, depth of discharge and charge rate, and is usually worse at the extremes.
- Prices are flat rates in pounds per kWh. Time-of-use prices and export rates that change through the day are not modelled.
- Round-trip efficiency is applied once per exported kWh, and the cost of charging is the only energy cost.
Technical details: what the fields mean
- Usable battery capacity
usableCapacityKwh - The energy the battery can actually deliver, in kWh. Check your car's specification or battery-health report.
- Round-trip efficiency
roundTripEfficiencyPercent - The share of charged energy you get back out. Some energy is lost as heat in the charger, cables and battery. 85% is a cautious default.
- Charging price
chargePricePerKwh - What you pay for each kWh put into the car, from your tariff. Use the cheapest rate you would actually charge at.
- Export (sell-back) price
exportPricePerKwh - What your supplier or aggregator pays for each kWh sent back to the grid. Use the rate in your export contract, not a headline figure.
- Battery replacement cost
replacementCost - The cost of a replacement battery pack, in pounds. Use a quote if you have one, or the cost you expect in future.
- Expected lifetime full cycles
lifetimeFullCycles - How many full charge-discharge cycles the battery is expected to last before it reaches end of life. Manufacturers publish warranty cycle counts; use the figure from your warranty if you have one.
- Full V2G cycles per year
cyclesPerYear - How many full-battery discharges you would run for V2G each year. Partial discharges count as a fraction of a cycle.
- Aggregator or hardware fee
fixedAnnualFee - Any yearly charge from the aggregator, bidirectional charger or software subscription. Leave at 0 if there is none.
Methodology
Battery wear cost per kWh = replacement cost ÷ (usable capacity × lifetime full cycles). This spreads the pack's cost over every kWh it is expected to deliver. Break-even export price = charging price ÷ round-trip efficiency + battery wear cost per kWh: each kWh exported needs more than one kWh bought, and each kWh discharged adds wear. Margin = export price − break-even export price. Annual net profit = full cycles per year × usable capacity × margin − fixed annual fee.
Worked example
60 kWh battery, 85% efficiency, £0.07/kWh off-peak charging, £0.30/kWh export, £6,000 pack, 3,000 lifetime cycles, 200 V2G cycles a year, no fee
Inputs: Usable battery capacity: 60 kWh, Round-trip efficiency: 85%, Charging price: £0.07/kWh, Export (sell-back) price: £0.30/kWh, Battery replacement cost: £6000, Expected lifetime full cycles: 3000 cycles, Full V2G cycles per year: 200 cycles, Aggregator or hardware fee: £0/yr
Result: About £2,211.76 a year net profit. Wear costs £0.033/kWh; break-even export price is £0.116/kWh; margin is £0.184/kWh.
Same battery, but the export price falls to £0.10/kWh
Inputs: Usable battery capacity: 60 kWh, Round-trip efficiency: 85%, Charging price: £0.07/kWh, Export (sell-back) price: £0.10/kWh, Battery replacement cost: £6000, Expected lifetime full cycles: 3000 cycles, Full V2G cycles per year: 200 cycles, Aggregator or hardware fee: £0/yr
Result: About −£188.24 a year. Below the £0.116/kWh break-even price, every cycle costs more in wear and charging than it earns.
Practical guidance
- Ask your supplier or aggregator for the export rate and any fees in writing before relying on a profit figure.
- Check whether your warranty covers V2G use. Some manufacturers limit or void cover for bidirectional discharging.
- Running a lower number of cycles per year keeps wear down. Compare a few cycle counts before committing.
Common mistakes
- Using the export price as the profit. You must also subtract the cost of the electricity you bought to replace what you exported, and the battery wear.
- Entering the total battery size from a brochure when the usable capacity is smaller.
- Forgetting that round-trip losses mean you buy more energy than you sell.
FAQs
What is V2G break-even?
It is the export price where income just covers the electricity bought to charge and the battery wear caused by discharging. Above it you make money; below it you lose money.
How much does V2G wear the battery?
Wear is modelled as replacement cost spread over the energy the battery can deliver in its lifetime. Enter your pack cost and expected lifetime cycles to see the wear figure per kWh.
Is V2G profitable?
It can be, but only when export rates are well above charging costs and the battery lasts a long time. Try the 'export price falls to £0.10' example to see how quickly the margin disappears.
Last reviewed: 2026-10-18
This is a simplified, flat-rate estimate. It uses a linear wear model and ignores warranty effects, temperature, charger losses beyond round-trip efficiency, grid-service payments and tax. It is not financial advice and should be checked against your actual contract and battery specification.
This tool provides an indicative estimate, based on the assumptions stated above.
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