Solar Battery Time-of-Use Tariffs UK: How to Cut Import Costs and Improve Solar Returns
Main article: approximately 1,500 words. Information and tariff examples checked on 3 August 2026.
A solar battery time-of-use tariff charges different electricity prices at different times. When rates are low, your battery can charge from the grid; when prices rise, it can power your home instead. With solar panels, the battery can also store daytime generation, reduce expensive evening imports and, where the tariff permits, export surplus electricity at more valuable times.
This guide is for UK homeowners considering solar and storage, and existing system owners wanting better returns. It explains how these tariffs work, how to compare them, what affects savings and why battery sizing and installation quality matter as much as the advertised unit rate.
Quick answer
A time-of-use tariff can increase the value of a solar battery by allowing it to charge during cheaper periods and discharge when grid electricity is expensive. The strongest results usually require a correctly sized battery, a working smart meter with half-hourly readings, scheduled charging and an off-peak window long enough to refill the battery. Solar owners must compare export rates as well as import prices: exporting solar can sometimes be worth more than storing it, particularly when the battery can be recharged cheaply later. Tariff rates, eligibility and compatible devices change, so compare the complete annual cost rather than choosing the lowest headline night rate.
Quick comparison: UK tariff structures
| Tariff type | How it works | Best for | Main consideration |
|---|---|---|---|
| Fixed off-peak | Cheaper electricity during set hours | Households wanting predictable battery charging | The battery must refill within the cheap window |
| Three-rate solar-and-battery | Off-peak, standard and peak import/export periods | Solar homes able to avoid or export during evening peaks | Peak imports can be costly if the battery empties |
| Dynamic half-hourly | Prices change every 30 minutes | Engaged users with compatible automation | Prices are less predictable |
| Supplier-managed battery | The supplier schedules charging and discharging | Homeowners wanting hands-off optimisation | Brand eligibility and control may be restrictive |
| Single-rate plus SEG | One import rate and a separate export payment | Low-use homes prioritising simplicity | It may not fully reward flexibility |
What is a solar battery time-of-use tariff?
A time-of-use tariff applies different unit rates during defined periods. Static tariffs use regular time blocks; dynamic tariffs can change daily or every half hour.
A compatible smart meter records when electricity is imported and exported, allowing the supplier to bill each period separately. Energy Saving Trust says smart meters can provide 30-minute readings and that these tariffs work best when demand can move away from peak periods.
The battery creates that flexibility automatically. Instead of asking a family to avoid cooking or entertainment during an expensive evening period, stored energy can supply the home.
How solar, storage and the tariff work together
A well-configured system normally follows three priorities:
- Use live solar electricity in the home, avoiding imports and battery conversion losses.
- Charge the battery economically from surplus solar or low-cost grid electricity.
- Use or export stored energy at the right time, covering peak demand or earning a worthwhile export payment.
The strategy changes seasonally. In summer, leaving capacity for daytime solar may be sensible. In winter, charging more during the cheap period may provide better value.
Energy Saving Trust confirms that batteries can charge when tariffs are cheap and provide energy later when prices are higher.
Current products illustrate the model. Octopus Flux has a low-rate period from 02:00 to 05:00 and a peak period from 16:00 to 19:00. British Gas offers battery tariffs with scheduled off-peak charging, including options for battery-only homes. Rates, postcodes and eligibility vary, so these are examples rather than recommendations.
Which tariff is best for a solar battery?
There is no universal best tariff. Compare:
- Annual electricity consumption
- Evening consumption
- Usable battery capacity
- Battery charge and discharge power
- Solar generation and export
- EV or heat-pump demand
A fixed off-peak tariff often suits families wanting predictable overnight charging. A three-rate tariff can suit homes with enough capacity to avoid the expensive peak window.
Dynamic tariffs may create greater opportunities, but they are better suited to automated systems that can monitor prices and adjust charging without constant manual intervention.
EV owners should compare the value of cheap vehicle charging with solar export income. Heat-pump homes must model winter demand carefully, while landlords may prefer a simple schedule that does not depend on tenant behaviour.
Import versus export: the calculation buyers often miss
The cheapest import tariff is not automatically the most profitable overall tariff.
Under the Smart Export Guarantee, eligible generators are paid for metered renewable electricity exported to the grid. Applicants generally need half-hourly export metering and evidence of an appropriately certified installation.
Import and export suppliers do not always need to be the same company, although individual tariffs may impose their own conditions.
When an export tariff pays more than the off-peak import rate, it may be financially better to export surplus solar and recharge the battery later.
However, allow for:
- Battery round-trip efficiency losses
- Battery degradation
- Tariff eligibility rules
- Export restrictions
- Inverter power limits
- Changes to tariff rates
The battery should not be charged and discharged merely because two headline prices appear different. The complete cost of each cycle matters.
Solar battery costs, savings and suitability
A roof survey is required before quotation.
What does solar system size mean?
Solar PV systems are rated in kilowatt peak, or kWp. This is the combined maximum rated output of the panels under standard test conditions. It is not continuous output and it is not annual generation.
A 4.5kWp array could, for example, use ten 450W panels. Actual production changes with sunlight, temperature, roof direction, pitch, shading and system losses. Panels still generate on cloudy days, but output is much higher in brighter months.
The inverter has a separate rating. Your quotation should clearly show panel capacity, inverter capacity and expected monthly and annual generation.
How to choose the right solar system size
1. Start with annual electricity use
Find the kilowatt-hours used over the last 12 months on your bills or smart-meter account. Do not use your monthly direct debit, which is a payment amount rather than an energy measurement.
The aim is not necessarily to generate exactly the same amount you consume annually. Solar production peaks during daylight, while many homes use most electricity in the evening. A system can export at midday and still import after sunset.
2. Consider when you use power
Solar is usually most valuable when used directly. Working from home, daytime appliance use, an immersion diverter, battery, heat pump or daytime EV charging may increase self-consumption.
Surplus electricity can earn Smart Export Guarantee payments. However, suppliers set their own rates, terms and eligibility conditions, so compare tariffs rather than assuming one fixed export price.
3. Assess the roof properly
A south-facing, unshaded roof is ideal, but east- and west-facing roofs can still perform well and spread generation across the day. Energy Saving Trust estimates they typically produce around 15–20% less than an equivalent south-facing system. Chimneys, trees, dormers and neighbouring buildings can also reduce output.
A survey should confirm usable dimensions, structure, cable routes and seasonal shading. Optimisers or microinverters may help with complex shading or multiple roof directions, but should be specified for a clear reason.
4. Include future demand
Tell the installer about likely EVs, heat pumps, extensions, air conditioning or a move towards electric cooking and hot water.
For an EV, annual mileage, vehicle efficiency and whether the car is home during daylight all matter. For a heat pump, remember that solar output is lowest during winter when heating demand is highest. Ask for monthly generation figures, not only an annual total.
5. Compare right-sized and maximum-roof options
Scaffolding, design and electrical work are partly fixed costs, so adding panels during the original installation may offer better value than returning later. Maximising a good roof can make sense when demand will grow, export rates are attractive or storage may be added.
But panels on heavily shaded or poor roof sections may add little value. Ask for two modelled options: a right-sized array and the maximum sensible array, each showing generation, self-consumption, export and financial assumptions.
Do I need a solar battery?
A battery does not decide the panel size, but it can increase the proportion of solar used at home by storing daytime surplus for later. Energy Saving Trust currently estimates typical battery-storage costs at around £5,000–£8,000.
Match storage to daily surplus and evening demand. Check usable capacity, charge and discharge power, warranty, backup capability and inverter compatibility. A battery can often be added later, but planning for it now may prevent duplicated equipment or labour.
Typical UK solar costs and value
| Item or household profile | Typical position | Buyer implication |
|---|---|---|
| 5kWh battery system | Around £4,600 as a broad benchmark | A retrofit or complex installation may cost more |
| Typical home battery | Around 10kWh, but property-specific | Size against usable evening demand |
| Battery lifespan | Commonly around 10–12 years | Compare warranty, cycles and retained capacity |
| High evening use | Stronger potential benefit | More peak-rate electricity can be replaced |
| Low use with high export | Export value may matter more | A large battery may be unnecessary |
| EV or heat-pump home | Higher flexible demand | Check charge power and winter performance |
Energy Saving Trust gives a broad battery price range of £1,500 to £10,000 and an indicative cost of about £4,600 for a 5kWh system. It also warns that savings will not justify every battery purchase.
Example savings calculation
Assume a battery:
- Delivers 8kWh during expensive hours
- Operates at 90% round-trip efficiency
- Charges at 8p per kWh
- Replaces electricity costing 26.11p per kWh
The gross energy-cost difference would be approximately £1.38 per full cycle, or roughly £500 across 365 identical cycles.
Actual savings could be lower or higher because solar output, battery state of charge, export income, degradation, household demand and tariff rates change throughout the year.
The 26.11p figure is Ofgem’s average capped electricity unit rate for direct-debit customers from 1 July to 30 September 2026. It is a comparison point, not a forecast of future prices.
Accurate quotations and payback estimates require a property survey and preferably 12 months of half-hourly consumption data.
How to choose the right solar battery and tariff
Collect real usage data
Download smart-meter information and identify how much electricity you use during peak periods.
Model summer and winter separately
Solar production, heating demand and evening consumption can vary substantially between seasons.
Choose usable battery capacity
The advertised battery capacity may not all be available because the system normally maintains a minimum reserve.
Check battery power output
Storage capacity is measured in kWh. Power output is measured in kW. A large battery with a low output may struggle to run several high-demand appliances together.
Confirm tariff compatibility
Check the smart meter, inverter, battery app, supplier integration and export requirements.
Compare total annual value
Include imported electricity, export revenue, battery losses, standing charges and peak-rate exposure.
Review the warranty
Compare warranty length, cycle limits, energy throughput and guaranteed remaining capacity.
Plan for future electricity use
Tell the designer about a planned EV, heat pump, extension, induction hob or electric heating system.
Request proper commissioning
The installer should explain seasonal schedules, minimum reserve settings, backup operation and app controls.
Does a solar battery time-of-use tariff work in winter?
Yes. Winter is often when grid charging becomes most useful because lower solar generation may not refill the battery.
Charging during an off-peak window can provide lower-cost electricity for the following day. The main limitation is capacity: heat pumps, electric heating and longer evenings can drain a small battery quickly.
In summer, the strategy may reverse. Preserving capacity for daytime solar can be more valuable than fully charging the battery overnight.
Weather-forecast-based control can reduce unnecessary grid charging and increase the amount of solar electricity stored.
Why the installer matters
Tariff optimisation cannot correct poor system design.
Battery location, cable sizing, inverter selection, export limitation, fire safety, ventilation, earthing and commissioning all affect performance, reliability and safety.
A competent installer should:
- Model your actual electricity consumption
- Explain whether backup power is included
- Confirm inverter and tariff compatibility
- Check Distribution Network Operator requirements
- Configure charging and export schedules
- Provide warranties and handover documents
- Explain how to change settings safely
Energy Saving Trust recommends obtaining at least three quotations from MCS-certified installers.
Final recommendation
For many solar-and-battery homes, a dependable low-cost charging window combined with a competitive export tariff is the best starting point.
Choose a dynamic or supplier-managed tariff only when the hardware is compatible and the household accepts variable prices or external control.
The strongest result comes from matching four elements:
- The home’s electricity load profile
- Battery capacity and power
- Seasonal solar generation
- Complete import and export tariff rules
Book a free home survey: Simple Green Energy can assess your roof, consumption, battery size and tariff options, then provide a tailored quotation rather than a generic savings claim.
Frequently asked questions (FAQs)
Clear answers about UK battery tariffs, smart meters, grid charging, off-peak periods, existing solar panels, battery sizing, winter savings, lifespan and battery degradation. Speak to Simple Green Energy .
Comparing battery and time-of-use tariffs?
Speak with Simple Green Energy about your smart meter, electricity usage, solar generation, battery capacity, off-peak charging window and the tariff strategy that may suit your home.
Review my battery tariff optionsConclusion:
A solar battery time-of-use tariff can reduce imported electricity costs and improve battery value, particularly for homes with substantial evening demand, an EV or a heat pump.
It is not automatically cheaper for everyone. Compare peak and off-peak rates, export payments, battery losses, compatibility and expected cycling before switching.
A well-designed system should work quietly in the background, storing energy when it is abundant or inexpensive and supplying it when grid electricity costs more.
The next step is a property-specific survey and annual energy model.
