Electricity no longer has one price a day. Across much of Europe, wholesale rates now swing from expensive evening peaks to hours of near-zero — or even negative — pricing at midday, as solar and wind generation surges. In Germany alone, negative electricity prices hit a record 573 hours in 2025, up 25% year-on-year, driven largely by midday solar oversupply.
For anyone running a battery system, that volatility is either a cost to absorb or an opportunity to capture — and the difference comes down to how the inverter is told to behave.
That's what Time-of-Use (TOU) mode is for. It's now standard across the full AESOLAR inverter lineup, including the newly launched Low-Voltage series — meaning every AESOLAR hybrid inverter can be scheduled to charge and discharge based on when electricity is cheap, expensive, or effectively free.
Two ways to run it
TOU mode offers both an automatic and a manual mode, so it fits both simple household setups and more complex commercial schedules.
In Automatic mode, the system runs on five pre-built price-based behaviors, applied across the hours of the week to match dynamic local tariffs:
- Peak Price Period — self-use, with the option to sell surplus power to the grid.
- Parity Price Period — straightforward self-use.
- Valley Price Period — keep 80% of power for self-use, with the option to purchase additional power from the grid.
- Super Valley Price Period — charge the battery at full power, keeping 95% of power for self-use.
- Negative Price Period — stop the PV system from charging the battery, and instead purchase electricity from the grid at full power to charge it, because when prices are negative, the cheapest electron is the one already on the grid.
In Manual mode, users define their own schedule instead: start and end times, charge/discharge status, cutoff SOC and current limits for each period, and whether battery-to-grid scheduling is enabled. The battery automatically stops charging or discharging once its set cutoff SOC is reached, giving installers and asset managers precise control for sites with their own tariff structures or grid agreements.
Why it matters now
TOU pricing isn't a niche feature anymore — it's becoming the norm as more countries introduce dynamic tariffs and as negative-price hours keep climbing across European markets.
A system that can only charge and discharge on a fixed schedule leaves savings on the table; a system that reacts to the actual price of electricity captures them automatically, day after day, without manual intervention.
Built into the whole lineup
Because TOU mode is built into AESOLAR's full inverter range, from established hybrid models to the new Low-Voltage series, the same intelligent scheduling logic scales from a single household battery to larger commercial systems, all configured through the same interface.
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