I just switched to Octopus Energy about a month ago. Haven't moved to Agile yet because I'm still waiting for my smart meter installation. But I've spent way too much time researching how the pricing works, so figured I'd write up what I've learned.
The basic idea
Most electricity tariffs charge you the same rate no matter what time of day it is. Boil the kettle at 3am or 6pm, same price.
Agile is different. The price changes every 30 minutes. And you know what tomorrow's prices will be in advance, because Octopus publishes them around 4pm each day.
That's the bit that surprised me. I assumed it was some kind of real-time spot pricing where you're gambling on costs. It's not. You can literally look at tomorrow's prices tonight and plan around them.
Where the prices come from
So how does Octopus decide what to charge every half hour?
They follow the wholesale electricity market. Here's what happens:
Power generators (wind farms, gas plants, nuclear, solar) sell electricity on the day-ahead market through auctions. The price for each half-hour slot gets set the day before. Octopus takes that wholesale price, adds their margin plus network charges and policy costs, and that becomes your Agile rate.
The wholesale price is basically driven by supply and demand. Loads of wind and nobody using electricity at 3am? Cheap. Everyone gets home at 5:30pm and turns on the oven, heating, and TV? Expensive.
Negative prices are real
This is the part that got me interested in Agile in the first place.
Sometimes the price goes below zero. As in, you get paid to use electricity. Sounds too good to be true but there's a boring practical reason for it.
Nuclear plants can't easily switch off. Wind farms get paid whether the grid needs their output or not. So when it's very windy overnight and demand is low, there's more electricity being generated than anyone wants. Generators end up paying to get rid of it, and that negative price passes through to Agile customers.
It doesn't happen every day. But it's not rare either. Windy weekends and sunny spring afternoons are the common ones. When it happens, that's the time to stick the washing machine on or charge the car.
The daily pattern
Even though the actual prices change daily, the shape of the day is fairly predictable:
Midnight to 6am is almost always the cheapest. Demand is rock bottom. Prices regularly drop below 10p/kWh. This is when you want to run anything you can schedule.
10am to 3pm is mid-range. Solar generation helps keep things reasonable, especially in summer months.
4pm to 7pm is where it gets painful. Everyone's home, cooking, heating. This is the peak. Prices can hit 30-40p/kWh, sometimes higher in winter.
After 8pm things start calming down again.
The takeaway is pretty simple. You don't need to rewire your life around this. Just avoid running heavy stuff during 4-7pm and you'll save money. Stick the dishwasher on before bed instead of after dinner. That's basically it.
What you need before switching
A smart meter. Specifically SMETS2, which is the current standard. Without one, Octopus can't measure your usage in half-hourly chunks and can't bill you on Agile.
If you've just joined Octopus, you can book a smart meter installation through the app. It's free but expect a few weeks wait. That's where I am right now.
While waiting, you can still check what prices look like in your area. The Octopus API is publicly available, and there are dashboards that show live and historical Agile rates across all 14 UK regions. I built one while I was researching all this, partly to understand the data and partly because the existing tools didn't show me what I wanted to see.
Is it actually cheaper though?
This is the question. And honestly, it depends on one thing: can you shift any of your usage away from the evening peak?
The Ofgem price cap right now is 24.5p/kWh. On most days, the Agile daily average comes in under that. But not always. And the average doesn't tell the whole story because nobody uses electricity evenly across the day.
Here's how I think about it:
If you run appliances overnight or during cheap midday slots, you'll save. Probably noticeably. People who do even basic stuff like running the washing machine at 10pm instead of 6pm seem to come out ahead over a year.
If literally all your usage happens between 4-7pm and you can't change that, Agile might cost you more on some days. Though even then, the cheap overnight and summer prices can offset it.
Seasonally, summer is great on Agile. Prices are low across the board. Winter evenings are the expensive bit. But even in January, overnight rates tend to be well below the price cap.
My plan
Once the smart meter goes in, I'm going to keep it simple:
- Washing machine and dishwasher on delay start, set to run overnight
- Charge phone and laptop overnight
- Try to avoid the 4-7pm peak for anything heavy
- Check next-day prices each afternoon
Nothing dramatic. Not setting alarms for 3am to do laundry. Just small adjustments.
I'll probably write a follow-up after a few months with actual numbers on whether it saved anything meaningful.
Links
- Octopus Energy Agile tariff details
- Live Agile rates and savings calculator
- Octopus public API if you want to pull the data yourself
