Negative price optimization
Stop exporting when selling does not pay, and use cheap energy when buying is free or paid.
→ Overview
The Negative price mode switches the strategy to special settings while electricity prices are zero or negative. It has two sets of values, one on each tab of its editor:
- Selling price optimization applies while selling energy to the grid earns nothing or costs money. Use it to stop exporting.
- Buying price optimization applies while buying energy from the grid costs nothing or pays you. Use it to consume as much as possible from the grid.
The prices come from the Utility Rate Plan of the controller. Without prices this mode never becomes active.
For the current time the controller takes the entry of the utility rate plan and calculates:
- Effective buying price = distributor energy + supplier energy buy + supplier energy buy fee.
- Effective selling price = supplier energy sell − supplier energy sell fee.
If the effective buying price is 0 or lower, the Buying price optimization values apply. Otherwise, if the effective selling price is 0 or lower, the Selling price optimization values apply. Otherwise the mode is not in effect.
The buying price is only checked when the plan has a supplier buy price for that time, and the selling price only when it has a supplier sell price.
→ Before you start
- The utility rate plan has prices for today and the coming hours. Open Utility Rate Plan in the left menu and check that the Purchase of electricity and Sale of electricity charts show bars. Prices are set up in the Reduxi Cloud. See Utility rate plan (electricity prices).
- The strategy does not use the AI energy manager. The two cannot be used together.
1 Add the negative price mode
0 kW and Goal at Self-consumption unless you have a reason to change them. Set the Import limit.0 kW. Set the Import limit to the power the site may draw while buying is free.
While Buying price optimization is in effect, the strategy charges the battery from the grid and lets EV chargers and heat pumps draw up to the Import limit. Set the Import limit no higher than the grid connection allows. The main fuses on the strategy's Details tab still apply.
Saving Settings → Grid with this strategy selected replaces the Export limit and Import limit of both tabs with the site values, for example the full import limit instead of the value you chose here. Check this mode again after you save the grid settings. See Grid settings.
2 Parameters
Selling price optimization
Applies while the effective selling price is 0 or lower and the buying price is above 0. In the diagram this is the red hatched area: from T1, where the selling fee becomes higher than the selling price, to T4.
| Parameter | What it does | Unit / default |
|---|---|---|
| Export limit | Maximum export while selling does not pay. 0 stops all export: PV is reduced so it only covers the site's own consumption and battery charging. |
kW · 0 |
| Goal | Goal while selling does not pay. Self-consumption keeps the grid power close to 0 and stores surplus PV in the battery. | Self-consumption |
| Import limit | Maximum import during this period. | kW · 5 |
| Advanced settings | Battery, PV, EVSE and HVAC settings for this period. They work as in the Default mode, see Optimization modes, goals and limits. | — |
Buying price optimization
Applies while the effective buying price, including fees, is 0 or lower. In the diagram this is the green hatched area from T3 to T4. It is checked before the selling tab, so it wins when both prices are negative.
| Parameter | What it does | Unit / default |
|---|---|---|
| Export limit | Maximum export while buying pays. Keep 0 so that energy you are paid to take is not sent back. |
kW · 0 |
| Goal | Goal while buying pays. Maximize consumption charges the battery from the grid and uses the grid up to the Import limit. | Maximize consumption |
| Import limit | Maximum import while buying pays. This is the power the site will try to draw. | kW · 5 |
| Advanced settings | Battery, PV, EVSE and HVAC settings for this period. On this tab, PV → Enable is No by default, so PV production stops while buying pays. | — |
Produce at price 0.00
In the PV panel of both tabs there is one extra field that other modes do not have.
| Parameter | What it does | Unit / default |
|---|---|---|
| Produce at price 0.00 | Tooltip: "PV is producing when price on Day-Ahead market is 0.00?". Yes keeps the negative price values out of effect when the price that would trigger them is exactly 0.00, so the Default mode (or a matching schedule) stays in effect and PV keeps producing. No lets the negative price values apply at exactly 0.00 as well. Available only while PV Enable is Yes on that tab. | Yes / No · No |
| Confirm | Closes the editor and adds or updates the Negative price row. Nothing is saved yet. | — |
Negative price row in the table
| Column | What it shows | Unit / default |
|---|---|---|
| Name | Negative price. The name is struck through, with an info icon, when the utility rate plan has no prices for today; the tooltip reads "To use AI strategy, you need to define a pricing plan". | — |
| Event description | Negative SPOT price. | — |
| Export limit / Goal / Import limit | One line per tab, for example "Negative selling price optimization with Self-consumption, export limit 0 kW and import limit 5 kW." | — |
| Advanced | Edit icon opens the editor. Bin icon deletes the mode after you confirm with Yes; click Save to make it permanent. | — |
A strategy can have only one Negative price mode. Clicking Create again shows a message instead.
3 How it works with other modes
- Voltage regulation wins over Negative price while the grid voltage is too high.
- Negative price wins over every Schedule entry and over the Default mode.
- AI energy manager cannot be added while Negative price exists, and Negative price cannot be added while the AI energy manager exists. The dialog shows: "The AI Energy Manager and specific optimizations (Negative Price, Battery, EVSE, and HVAC) are mutually exclusive."
- Battery optimization, EVSE optimization and HVAC optimization can be used together with Negative price. Their device setpoints still apply while Negative price is in effect. See Battery, EVSE and HVAC optimization.
4 Check the result
On the strategy's Last measurements tab, in the Main settings card, Optimization shows:
-
Negative buying pricewhile the Buying price optimization values apply; -
Non-optimal selling pricewhile the Selling price optimization values apply.
5 Checklist
- The utility rate plan has buy and sell prices for the coming hours, and the Negative price row is not struck through.
-
Selling price optimization: Export limit
0kW, Goal Self-consumption. -
Buying price optimization: Goal Maximize consumption, Export limit
0kW, Import limit within the grid connection. - Produce at price 0.00 is set as agreed with the site owner.
- The values are still correct after the last save of Settings → Grid.
- Save was clicked.