Time-of-Use Tariffs: Solar Optimisation

Time-of-use tariffs pay you more for exporting during peak hours and charge less overnight. Here's how they work with plug-in solar and a smart meter.

Why Time-of-Use Tariffs Suit Solar Owners

A standard flat-rate tariff charges you the same per kWh regardless of when you use electricity. A time-of-use (ToU) tariff varies the rate by time of day — typically offering cheap overnight rates, standard daytime rates, and expensive peak evening rates.

For plug-in solar owners, this creates a double opportunity:

Your panels generate during the day when rates are standard — offsetting mid-price import
You export during the day when the grid is relatively well-supplied — but some tariffs still pay decent rates
You can shift heavy loads to cheap overnight periods using a timer

A SMETS2 smart meter with half-hourly settlement is required for ToU tariffs. Without it, your supplier can't bill you at the correct rates.

Octopus Flux: The Solar-Specific Tariff

Octopus Flux is designed explicitly for solar and battery owners. It has three time bands:

Off-peak (02:00–05:00) — cheapest import rate; charge your battery here
Day (05:00–16:00 and 19:00–02:00) — standard rate
Peak (16:00–19:00) — highest import rate, but also highest export rate

The peak export rate is the key feature. If your panels are still generating at 16:00–17:00 (common in summer), or your battery discharges stored solar during peak, you earn the most.

For plug-in solar without a battery, the benefit is mainly avoiding peak import rather than earning peak export — your panels produce less in the late afternoon, and a 400–800W system may not export much during peak hours.

Octopus Go: For EV Owners with Solar

Octopus Go gives you a very cheap overnight window (typically 00:30–05:30) and a flat rate the rest of the day. If you have an EV, charge it overnight at the cheap rate and use your solar during the day for household loads. The smart meter tracks which kWh fall in which time band.

Agile Octopus: Advanced, Variable Pricing

Agile charges a different rate for every half-hour slot, tracking wholesale prices. On sunny days when solar farms are flooding the grid, daytime prices can drop very low (occasionally negative). On dark winter evenings, prices spike.

This tariff rewards solar owners who are actively engaged — watching prices and shifting loads accordingly. The smart meter is essential here, as billing depends entirely on half-hourly settlement.

It's higher effort than Flux or Go but can save more for people who actively manage their consumption.

How to Switch to a Time-of-Use Tariff

Confirm you have a SMETS2 smart meter (check here)
Ensure half-hourly settlement is active — ask your supplier
Research available ToU tariffs from your supplier and competitors
Switch via your supplier's app or website — takes 1–2 weeks
Set up timers on heavy appliances to run during off-peak windows

Is It Worth It for Plug-in Solar?

For a plug-in solar system without a battery, the benefit is modest. You save on avoided import during the day (which you'd save on any tariff), plus potentially cheaper overnight rates for baseline loads. Typical additional saving over a flat tariff: £30–80/year.

For a plug-in solar system with a battery, the benefit is significantly larger. You charge the battery overnight at cheap rates and from solar during the day, then discharge during expensive peak hours. Additional saving: £80–200/year depending on battery size and tariff.

Use our savings calculator to model the difference for your specific setup and location.

TOU tariffs available to UK solar households in 2026

The UK TOU landscape has consolidated since 2024. The tariffs still worth considering for a plug-in solar household:

Tariff	Peak rate	Off-peak rate	Export rate	Best for
Octopus Agile	Variable half-hourly (avg 22–28p, peaks 90p+)	Variable (avg 12–18p, dips <5p or negative)	Outgoing Agile ~10p avg	Data-driven load-shifters
Octopus Go	27p flat day	8.5p (00:30–05:30)	15p Outgoing Fixed	EV owners with plug-in solar
Octopus Flux	32p (16:00–19:00)	15p (02:00–05:00)	27p (16:00–19:00)	Solar + battery only
Octopus Cosy	39p (16:00–19:00)	12p (04:00–07:00, 13:00–16:00)	15p Outgoing Fixed	Heat pump owners with solar
EDF GoElectric 35	34p peak	8.99p (00:00–05:00)	5.6p SEG	EV + solar households
British Gas Electric Driver	30p peak	7.9p (00:00–05:00)	6.4p SEG	Multi-vendor BG loyalists

For a plug-in-solar-only household with no EV and no battery, Octopus Agile is usually the highest-yielding pick because the negative-price dips (real, happened 42 times in 2026 so far) let you plan discretionary loads for genuinely free electricity. See the Octopus Agile plug-in solar guide.

The battery arbitrage angle

Add a portable battery like the EcoFlow DELTA 2 and the maths changes materially. You charge from the grid during the cheapest window (Octopus Flux 15p, or Agile's negative-price hours) and discharge during the peak (Flux 32p, Cosy 39p). Combined with midday solar charging, a 1 kWh battery on Flux typically nets £180–£260/year in arbitrage on top of self-consumption savings. See the battery arbitrage guide for the full spreadsheet.

When TOU is a bad idea

TOU tariffs are not universally better. Skip them if:

Your household is home 4–7 pm every evening with high demand (cooking, kids, TV, showers) — the peak-rate exposure often outweighs solar/off-peak savings
You are on prepayment or in fuel poverty risk — variable pricing volatility can be genuinely dangerous
Your consumption is under 2,500 kWh/year total — the fixed daily standing charge changes swamp the unit-rate savings on tiny consumption
You do not have a SMETS2 meter with reliable half-hourly settlement — TOU requires it