If you have plug-in solar panels and you are still on a standard variable electricity tariff, you are leaving money on the table. Significant money.
The combination that most experienced solar users end up on is Octopus Agile — a tariff where the price changes every 30 minutes based on wholesale electricity costs — paired with a plug-in solar setup generating free electricity through the middle of the day. Done right, the two complement each other almost perfectly, and your monthly electricity bill can drop to a fraction of what you were paying before.
Here is how it works and how to get the most out of it.
What Octopus Agile actually is
Octopus Agile is a half-hourly variable tariff. Octopus publishes the next day’s prices at around 4pm each afternoon, and you pay exactly those prices for whatever you use in each 30-minute slot. On a good day — when wind is blowing strongly or when UK solar generation peaks — prices can go negative, meaning Octopus literally pays you to use electricity.
On a bad day — typically a cold, still weekday evening in January when demand is high and renewable generation is low — prices can spike. The highest Agile prices I have seen have hit 50p or 60p per unit. The lowest have been minus 50p or so, meaning 50p earned per unit used.
The trick is to shift your usage away from expensive slots and into cheap or negative ones.
Where solar fits in
A plug-in solar setup generating electricity between about 9am and 3pm is doing something that interacts brilliantly with Agile pricing.
First, it is reducing your grid draw during daytime hours — hours that are often reasonably cheap on Agile but not reliably so. Every unit your panels produce is a unit you are not buying.
Second, midday in summer is exactly when Agile prices most often go negative or very low. This is because the UK’s solar generation capacity has grown enormously and on a clear summer afternoon the grid can have more power than it needs. When that happens, prices crash. Your panels are generating for free at exactly the moment grid prices are at their lowest or negative.
Third, if you run high-draw appliances at midday — washing machine, dishwasher, EV charger — you consume solar first (which is free) and you are doing so during the window when grid electricity is cheapest anyway. Both benefits stack.
The overnight cheap rate: the other half of the equation
Solar takes care of your daytime electricity. Agile takes care of the rest.
Overnight, Agile prices are typically at their lowest — often in the 2p to 8p range, sometimes lower. This is when you should be charging anything that can store energy: an electric vehicle, a home battery if you have one, a plug-in solar battery kit like the EcoFlow STREAM with its optional home battery.
If you run a dishwasher or washing machine overnight rather than during the day, you can also shift those loads into cheap slots. The Octopus app shows tomorrow’s prices from 4pm, so setting a delay timer on your appliances for the cheapest 30-minute window is straightforward.
The numbers: what does this actually save?
The average UK household uses around 3,500 kWh per year. At the standard rate cap of around 24-25p per unit, that is roughly £840 to £875 per year in electricity costs.
A modest plug-in solar setup — a single 400W panel with a micro-inverter, south-facing, in central England — generates around 350 to 400 kWh per year. At 25p, that is £87 to £100 of avoided grid electricity.
On Octopus Agile, a household that actively manages loads and avoids expensive slots can reduce their average unit rate from 25p down to 10p to 15p, sometimes lower. On that same 3,500 kWh, the saving versus standard rates is £350 to £525 per year.
Stack both: solar removes the need to buy 350 to 400 kWh from the grid at all, and Agile reduces the price of everything else. Together, £400 to £600 per year in savings is a realistic target for a household with a single-panel setup and active load management.
Two panels running 800W doubles the solar saving. A home battery to store midday solar generation for evening use, or to store cheap overnight Agile electricity for daytime use, can push the total saving further still.
Setting it up: the practical steps
Step 1: Get a smart meter if you do not have one. Agile requires it. Contact Octopus through their app or website and they will arrange installation, usually within a few weeks.
Step 2: Switch to Octopus Agile. You can do this through the Octopus app. If you are already an Octopus customer on a different tariff, it is a tariff change, not a full switch.
Step 3: Install the Octopus app and check prices daily. Prices publish at 4pm for the next day. Get into the habit of glancing at them and deciding which slots are worth timing your big loads to.
Step 4: Set delay timers on appliances. Most washing machines and dishwashers have a delay start timer. Set your washing machine to run at the cheapest overnight slot, or in the midday solar window if you want to use solar generation.
Step 5: Monitor your solar generation. The EcoFlow STREAM app shows live generation. On days when you know you are generating well, running extra loads at midday is free — or nearly free.
Step 6: Consider automation. Home Assistant and similar home automation platforms can automatically switch smart plugs and appliances based on Agile prices. Set a rule: when Agile price is below 5p, switch on the immersion heater. It is a small amount of setup that pays off indefinitely.
A note on export
Plug-in solar systems in the UK cannot currently access the Smart Export Guarantee — the scheme that pays you for electricity you export back to the grid. Your inverter exports automatically, but there is no formal metering or payment for it under current regulations.
This is one reason to try to use your solar generation yourself rather than exporting it. Agile’s cheap daytime slots are an incentive to use grid electricity at those moments, but if you have solar generating at the same time, use the solar first — it costs you nothing.
The SEG situation for plug-in solar is expected to change. The government’s 2026 review of plug-in solar regulations includes examination of export payment access. Watch this space.
Is Octopus Agile right for everyone?
Not necessarily. Agile rewards households that are home during the day, have appliances they can shift around, and are comfortable with a degree of price variability. If you are out all day and run your appliances in the evening, Agile can be expensive — evening prices are often higher than the standard rate cap.
Octopus Go is a better fit for households that want simplicity: a fixed cheap rate overnight (currently around 7.5p/kWh for a 5-hour window), and standard rates the rest of the time. Pair that with solar covering your daytime use and you still make significant savings without the complexity of tracking half-hourly prices.
The savings calculator on this site lets you estimate what your setup would save on different tariffs. Run the numbers for your own usage pattern before switching.
The bottom line
Octopus Agile and plug-in solar are the best bill-cutting combination currently available to most UK households. Solar handles the middle of the day for free. Agile gives you cheap rates at night and access to negative prices when the grid is flush with renewable power.
Neither one alone is as good as both together. If you have already installed your panels and you are not on a smart tariff yet, this is the next step worth taking.