Time-of-Use Tariff vs SEG Only

Which Is Better: A Time-of-Use Tariff or SEG Only?

Neither is better for every home; the right choice depends on whether your surplus solar is worth more exported or used on site. According to Ofgem’s Smart Export Guarantee annual report, there were 283,666 SEG installations by March 2025 and 99.98% were solar PV, showing how central export economics have become in UK solar decisions. See also: BUS Grant 2026 guide, heat pump cost guide.

For most homeowners, that means this is not a debate between right and wrong but between two ways of valuing the same generation. SEG only income pays you for power you do not use. Time-of-use tariff saves you from buying electricity at retail prices. Read our complete guide to solar panels in the UK, smart export guarantee guide, and solar battery storage article. If your wider project also includes a heat pump, our BUS grant survey page is the route for eligible domestic ASHP applications, subject to eligibility.

What Are the Main Differences Between the Two?

The main differences are how the value is captured and how dependent that value is on your household demand pattern. According to Ofgem, SEG payments are made for eligible exported electricity, while self-consumption reduces the amount of electricity you need to import from the grid.

The practical comparison looks like this:

Prices and services correct at time of writing — always request a current quote.

That means SEG income is simpler to understand because it gives a visible payment for surplus electricity. Time-of-use tariff can be more valuable per unit, but only if the household can genuinely use more of its generation at home. The better answer depends on tariff rates, import prices, and demand timing.

Which One Usually Makes More Sense Financially?

Time-of-use tariff often makes more sense financially because imported electricity is usually worth more than exported electricity. According to Ofgem (April 2026), the typical direct-debit electricity cap is 24.5p/kWh, which is substantially higher than many SEG export rates available to UK households.

That price gap is why batteries, heat pumps, EV chargers, and hot-water diverters can all improve the economics of solar: they increase the amount of generation used on site rather than exported. But self-consumption is not automatically better in every home. If a household is empty all day and has no way to shift demand, SEG income may remain a large part of the value case. The best answer depends on whether the home can actually use more of its own solar rather than on theory alone.

Typical financial decision points include:

1. what import tariff and export tariff you are comparing
2. how much daytime or shiftable demand the home has
3. whether the project includes a battery, EV charger, or heat pump
4. whether you prioritise simplicity or deeper optimisation

What Do Homeowners Most Often Get Wrong?

The most common mistake is assuming exported solar must be “wasted” solar. According to Ofgem’s SEG framework, exported electricity still has clear value because it can be paid for under eligible export tariffs. The real question is whether that exported unit would have been worth even more if used on site.

Another mistake is assuming self-consumption is always the better answer because the per-unit value is often higher. In practice, that only matters if the home can use more of its own generation. A battery, diverter, heat pump, or EV charger can change that. Without them, some households will still export a large share of solar output. The best answer depends on actual demand timing, not just on which column of the spreadsheet looks more efficient in theory.

Typical comparison mistakes include:

• assuming exported power has no value
• assuming self-consumption is always maximised automatically
• ignoring real household demand timing
• overlooking the role of batteries and flexible loads

What Does This Mean in London, Surrey, and TW Homes?

In London, Surrey, and TW homes, self-consumption usually becomes more attractive where the project includes a heat pump, EV charger, battery, or all three. According to Ofgem (April 2026), imported electricity remains expensive enough that using more of your own generation can materially improve the economics of wider electrification.

SEG only income can still be very relevant where the household is out during the day and has limited flexible demand. But for many South East family homes, the more strategic question is how to increase self-use rather than how to maximise export alone. That is particularly true once the project extends beyond basic PV into whole-home electricity demand. The better answer depends on the household profile, not on a generic rule.

That is why project-specific design matters more than blanket claims about export or self-use. Our solar battery storage article, smart export guarantee guide, and heat pump solar combo guide help make that decision more practical.

This is also where load-shifting technology changes the economics. A battery, diverter, EV charger, or well-controlled heat pump can all move more generation into useful on-site demand and shrink the export share. Without those flexible loads, export remains an important part of the value case. That is why the best design is usually the one that measures likely usage honestly instead of treating self-consumption as an automatic win.

How Electromatic Can Help

If you are comparing export tariff vs time-of-use tariff optimisation, the next step is to review your demand profile, tariff assumptions, and whether the project should also include battery storage, EV charging, or a heat pump. According to Ofgem guidance, the value of solar depends heavily on whether the electricity is used on site or exported.

Electromatic can assess whether your home is better suited to a simpler export-led solar design or to a more optimised self-consumption route. We work under MCS certification via our accredited umbrella partner, and where the installation is eligible we can also handle BUS grant applications for air source heat pumps, subject to eligibility. We can coordinate ASHP, solar, battery storage, and wider electrical planning through one contractor.

That gives you a whole-project answer rather than a tariff decision in isolation. It also makes the value case more credible because import, export, and self-use assumptions are visible before you commit.

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Call us: 07718 059 284 | Email: admin@electromatic.uk

Frequently Asked Questions

Most follow-up questions on export tariff vs time-of-use tariff optimisation are really about whether exporting is ever still worth it. According to current Ofgem guidance, it is, but the stronger answer depends on tariff rates and the household’s ability to use more of its own generation.

How much more valuable is self-consumption than export?

Often it is more valuable per unit because avoiding imported electricity can be worth more than many export rates, but the real answer depends on your tariffs.

Is SEG income still important?

Yes. It is still a meaningful part of the solar value case, especially if the household exports a large share of generation.

Does a battery change this comparison?

Yes. A battery usually shifts value towards self-consumption because it stores surplus generation for later use at home.

Does this matter more if I also have a heat pump?

Yes. A heat pump raises electricity demand, which often makes self-consumption more valuable within the home.

Which option makes more sense in Surrey and TW homes?

If the project includes broader electrification, self-consumption usually becomes more attractive. If daytime demand is low and you do not want extra hardware, export income still matters.

The information in this article is for general guidance only and does not constitute financial, legal, or technical advice. Energy savings estimates are based on typical UK household data from the Energy Saving Trust and Ofgem (April 2026 price cap). Actual savings depend on your property type, insulation levels, energy usage patterns, and electricity tariff. The Boiler Upgrade Scheme (BUS) grant of £7,500 is subject to eligibility criteria set by Ofgem — not all properties qualify. Electromatic M&E Ltd operates under MCS certification via an accredited umbrella partner. All installations comply with Building Regulations Part L and MCS standards. E&OE.

Written by Electromatic M&E Ltd — ASHP & Solar installer, London & Surrey (electromatic.uk)

Last updated: April 2026 | Electromatic M&E Ltd, Company No. 13837345