1. Understand how your selling price is calculated
A negative electricity market price is a price below zero for a particular trading interval. On its own, it does not describe all the revenue and costs of your solar PV plant. The contract formula, deductions and the way deviations from submitted schedules are settled all matter.
Check what happens at zero and negative prices. Establish whether the contract follows the exchange, uses a fixed price or applies another formula. Note the schedule submission deadline as well: changing sales can create a deviation from an already submitted schedule.
2. Set a grid export threshold
To stop PV electricity sales automatically, choose a minimum price based on the actual purchase terms. A threshold of zero alone may not reflect the costs of each unit of energy sold. Include applicable deductions and the operating rules of your site when setting it.
The controlled action is stopping or limiting sales to the grid. Check separately how self-consumption and battery charging work. Solar generation, loads and storage are parts of one system, but they perform different functions.
3. Check whether the battery has available capacity
A battery can absorb some daytime generation when it has spare capacity and sufficient permitted charging power. A full battery cannot accept more energy, while a small inverter may limit the amount transferred during a short interval. Capacity in kWh and power in kW therefore need to be considered together.
For later sales, compare the evening price with the value of direct exports, energy losses and battery use. You can adjust the prices and costs in the public calculator. Explore how the result changes instead of choosing a rule based only on a high price during one hour.
4. Monitor the actual result
Check measured exports after a mode change. A requested limit, a sent command and measured power are different data points. Inverter monitoring and controller acknowledgements help establish whether the rule was carried out.
- Check the time interval and price that triggered the threshold.
- Compare measured exports with the requested limit and the sales schedule.
- If deviations recur, review the power limits, battery and settings with your service team.