Daily guide · UA · 2026-09-06
What a home battery earned in Ukraine this week, hour by hour
All numbers computed from the week's published auction results at publication and frozen — this article is an honest snapshot, not a page that rewrites itself. Reproduce via the API.
A 10 kWh battery cycling once a day earned 573,08 EUR across the six days on record this week, an average spread of 10.644,54 EUR/MWh between the cheap and peak windows. The pattern was remarkably consistent: on most days the cheapest hours clustered around late morning, from 09:00 to 12:00, while the evening peak landed at 19:00 or 20:00. Charging midday and discharging into that evening ramp was the whole trade.
The standout day was 3 September, when the peak averaged 14.926,87 EUR/MWh and a single cycle returned 122,79 EUR. The weakest was 4 September at 66,76 EUR, the one day the peak arrived early at 06:00 rather than in the evening, and the cheap window shifted to midday with an average of 524 EUR/MWh. That break in rhythm cost roughly half a day's earnings.
The takeaway: the evening peak did the heavy lifting all week, so the discipline that matters is holding charge for 19:00 to 20:00 rather than discharging early. At a 90 percent round-trip efficiency and this week's spreads, the annualised figure works out to 34.862 EUR.
A home battery makes money on one thing: the gap between the day's cheapest and priciest hours. Charge low, discharge across the evening peak instead of buying it, repeat daily. The size of that gap is set every afternoon at the day-ahead auction — so it's measurable, not hypothetical. Here is what one full daily cycle of a 10 kWh battery (at 90% round-trip efficiency — losses included, unlike most brochures) would have captured in UA this week.
€573.08
captured this week — one cycle per day, wholesale component, after losses
10644.54
€/MWh average cheapest-2h → priciest-2h spread this week
≈€34862
a year at this week's spreads — the honest run-rate, not the best-day fantasy
Day by day: the two windows that mattered
| Day | Charge (2h) | at €/MWh | Discharge (2h) | at €/MWh | Cycle value |
|---|---|---|---|---|---|
| 2026-08-30 | 09:00–11:00 | 10 | 19:00–21:00 | 10037 | €90.23 |
| 2026-08-31 | 10:00–12:00 | 10 | 19:00–21:00 | 12261.85 | €110.26 |
| 2026-09-02 | 11:00–13:00 | 10 | 19:00–21:00 | 12610.5 | €113.39 |
| 2026-09-03 | 11:00–13:00 | 1155 | 19:00–21:00 | 14926.87 | €122.79 |
| 2026-09-04 | 12:00–14:00 | 524 | 06:00–08:00 | 8000 | €66.76 |
| 2026-09-05 | 11:00–13:00 | 10 | 20:00–22:00 | 7750 | €69.65 |
Local time, hourly auction means. Days where charging was negative-priced mean you were paid to fill the battery.
Do it automatically
The windows move every day — automation is the whole game. One API call returns a cost-optimal schedule your inverter or energy manager can follow, and there's a full battery simulator to backtest your exact capacity, power and cycle limits against realized prices before you trust it:
curl -X POST -H "Authorization: Bearer YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"zone": "UA", "capacity_kwh": 10, "max_power_kw": 5,
"round_trip_efficiency": 0.9, "max_cycles_per_day": 1}' \
https://voltcast.com/api/v1/optimize/batteryHome Assistant users get the schedule as a sensor via the integration. And because the value depends entirely on tomorrow's spread, the P10–P90 forecast — scored publicly every day — tells you whether tomorrow is worth a deep cycle at all.
Method & citation. Prices are hourly means of published day-ahead auction results (native 15-minute periods averaged; ENTSO-E/SMARD, attributed). Wholesale-price component only — grid fees and taxes come on top and vary by supplier. Cite as "Voltcast Research, voltcast.com/guides/battery-arbitrage-ua-2026-09-06".
Next issue 2 Oct
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