Guides
What are negative electricity prices?
Negative prices mean the unit rate drops below 0p/kWh for a slot, but the standing charge still exists.
Short answer
A negative Agile slot means the electricity unit rate for that half-hour is below 0p/kWh. You still pay the standing charge, but flexible demand becomes unusually cheap for that specific slot. These events are interesting because they can make optional loads feel almost free, but they still need to be understood in the context of the whole day.
If you want live context while reading, check the dashboard, test a real run in the appliance timer, set a trigger in alerts, or compare the same day across regions.
Why they happen
Negative prices usually appear when supply is strong relative to demand, often overnight or in windy conditions. They are unusual enough that checking manually is easy to miss. That makes alerts more useful than trying to watch the chart constantly. When they do happen, the rest of the day can still be expensive.
Best uses
They can be useful for flexible loads such as dishwashers, immersion heating, or EV charging if the rest of the day is managed sensibly. The main question is whether you have a real load to move into that slot. If not, the negative price is interesting but not necessarily useful. Use the dashboard and appliance timer together to judge whether the window actually fits a task.
Alerts help
Negative prices are rare enough that alerts are often a better tool than checking manually. A simple trigger is usually enough because the event itself is already uncommon. If you prefer planning ahead, combine an alert with tomorrow-price notifications. That way you know both when a rare event happens and what the rest of the day looks like.
Example
A unit rate can drop below 0p/kWh, but the standing charge still exists. That means the slot is unusually cheap, not that the whole day becomes free. A negative overnight slot can be a good time to top up an EV or heat water if later peak slots are expensive.
What to watch out for
Negative unit rates do not mean your whole day is cheap. Later peak slots can still be very expensive, and the standing charge still applies regardless of one negative half-hour.
Related tool
Use the practical view next
Related guides
Is Agile Octopus worth it?
Agile suits households that can shift meaningful usage away from the evening peak.
Best time to run a washing machine on Agile
The best slot is not always the most practical slot, so compare cheap windows against when you actually need the cycle to finish.
Best time to charge an EV
Agile can work for EV charging when you have enough overnight or daytime flexibility.
Reminder
These guides are practical and estimate-focused. They are not personalised tariff advice, and they do not replace a full bill comparison.