British Gas PeakSave Sundays and home batteries

A growing number of UK energy customers have tariffs that do not fit a simple daily template.

The problem is easy to describe. The customer may have cheap electricity on Sunday, or a different weekend pattern, but the energy dashboard only asks for a start time and an end time. It assumes the same periods apply every day.

That is fine for many fixed overnight tariffs. It is not enough for every home.

For solar and battery customers, this matters because the tariff shapes how the customer understands grid charging, daily cost, EV charging, export value and supported battery behaviour.

The quick version

British Gas PeakSave is a useful public example of the problem. British Gas describes Sunday-specific half-price electricity windows, including 11am to 4pm for PeakSave Sundays and 9am to 5pm for PeakSave Super Sunday tariff customers.

A normal tariff editor that only stores times can miss that detail.

1app.energy now supports a clearer manual tariff model for these cases:

• choose the day you want to edit;
• set that day's import periods and prices;
• copy the day to other matching days when the tariff is the same;
• keep a different Sunday, weekend or special weekday pattern when needed.

This keeps the default path simple for most customers, while giving enough flexibility for homes whose tariff changes by day.

Why Sunday tariffs break simple home energy apps

Many energy apps treat a tariff as one 24-hour pattern.

That means the customer can enter something like:

For a tariff that repeats every day, that is understandable.

But a day-specific tariff needs another question:

Which days does this price apply to?

Without that question, the app has to make a poor choice. It either applies the Sunday rate every day, ignores the Sunday rate, or asks the customer to force a real tariff into the wrong shape.

That is where frustration starts.

The customer is not asking for a complicated finance tool. They are asking the app to understand the tariff they actually have.

Why this matters more for battery homes

A simple electricity bill can tolerate some rough mental maths. A battery home cannot.

A battery customer may want to know:

• whether the battery charged during the cheapest period;
• whether Sunday grid charging was cheaper than a weekday top-up;
• whether an EV session used cheap grid energy, solar or stored battery energy;
• whether export credit and import cost are being shown against the right clock time;
• whether a supported Smart Control mode has the right tariff context.

If the tariff model is wrong, the app can tell the wrong story even when the inverter data is correct.

For example, imagine a home with a Solis inverter, a home battery and a fixed Sunday discount.

If Sunday 11am to 4pm is cheaper, the customer may reasonably choose to fill the battery then. But if the app only understands times and not days, it may show that same cheap period for Monday, Tuesday, Wednesday and every other day.

That makes daily cost harder to trust.

It can also make supported battery behaviour harder to explain, because the app no longer knows which day has the cheaper window.

What 1app.energy changed

1app.energy's manual Rate Plan now works one day at a time.

The customer chooses Monday, Tuesday, Wednesday, Thursday, Friday, Saturday or Sunday. The screen then shows the tariff periods for that selected day only.

If every day is the same, the customer can set one day and copy it to the rest of the week.

If Sunday is different, the customer can edit Sunday separately.

If weekdays and weekends differ, the customer can copy a weekday pattern to Monday to Friday, then set Saturday and Sunday as needed.

The aim is to keep the mental model simple:

This avoids the confusing version where one long list contains periods for every possible day. The customer sees the day they are editing, checks the prices for that day, and copies only when that is useful.

For the wider setup basics, read manual tariff setup for solar battery and EV homes.

What this means for British Gas PeakSave customers

PeakSave is a good example because the discount is tied to Sunday.

A customer should still check their own British Gas account, tariff terms and smart meter setup before entering rates. Supplier rules and eligibility can change, and the actual unit rates depend on the customer's plan and region.

But the shape is exactly the kind of tariff a home energy app needs to handle:

• normal pricing for much of the week;
• a Sunday-specific cheaper window;
• a daily standing charge that still applies normally;
• a battery or EV decision that may depend on when cheap energy is available.

With day-specific manual tariffs, a customer can represent that shape more honestly.

That does not mean 1app.energy controls every battery, every inverter or every charger. Automation still depends on supported devices, verified setup and customer-enabled controls.

It does mean the tariff context can be closer to the customer's real bill.

The Solis and AC-coupled solar point

Some homes have another layer of complexity: solar generation may not be measured by the inverter API.

For example, a customer may have solar coming through microinverters on the AC side, while the Solis battery inverter mainly reports battery and grid behaviour. In that setup, the inverter can be working, but the solar number in the inverter app may still show zero because the PV is not measured through that inverter.

That is a topology issue, not a tariff issue.

Day-specific tariff setup can help price grid import more accurately. It cannot invent solar readings that the connected device does not report.

This is why 1app.energy separates tariff context, device telemetry and topology. A clear tariff editor helps with the cost side. Correct metering and supported device data still decide what the dashboard can show for solar, battery, grid and EV flow.

For more on this principle, see home energy dashboard source of truth: what to check and why solar dashboard numbers do not add up.

Why this is useful for installers too

Installers often hand over strong hardware, but the customer's daily experience still depends on software.

A customer with a Solis inverter, battery, EV charger and Sunday-specific tariff does not want to be told that their tariff is too unusual. They want a clear place to put the correct rates and understand what the home is doing.

A better tariff setup helps installers because it gives customers a cleaner explanation after handover:

• this is your normal weekday pattern;
• this is your cheaper Sunday period;
• this is when the battery may be worth charging from grid;
• this is what the app can see from the inverter;
• this is what depends on extra metering, charger data or supported controls.

That is more useful than asking the customer to fit a real tariff into a generic 24-hour template.

How 1app.energy fits in

1app.energy is a customer-facing app layer for renewable homes: one app for solar, battery, EV and tariff.

For supported homes, that can include live energy flow, Solis inverter context, battery behaviour, EV charging context, tariff-aware visibility and supported Smart Control where the customer enables it.

The day-specific tariff change strengthens the manual tariff path. It is especially useful for non-Octopus or fixed supplier tariffs where live tariff sync is not the right source.

Octopus-style dynamic pricing is still a different problem. Half-hourly dynamic tariffs need live supplier pricing where supported, because the rate can change far more often than a fixed weekly pattern.

For fixed day-specific tariffs, manual setup can now describe the week much more clearly.

For battery behaviour, read which 1app smart control mode should you use.

Common questions

Does this mean 1app.energy supports British Gas PeakSave automatically?

No. This article is about manual tariff setup.

British Gas PeakSave is a public example of a Sunday-specific tariff shape. Customers should enter their own rates from their supplier account, tariff confirmation or bill.

Can I set a different tariff for Sunday only?

Yes. In manual Rate Plan setup, select Sunday and edit the Sunday prices. If the other days share the same pattern, set one weekday and copy it to the matching days.

What if my Saturday and Sunday are both different?

Edit Saturday, then edit Sunday. Each selected day shows its own periods, so you do not have to read one long mixed list.

Will this change my inverter settings?

Changing manual tariff periods gives 1app.energy tariff context. It does not by itself prove that an inverter, battery or EV charger can be controlled.

Supported Smart Control still depends on verified devices, customer enablement and backend safety checks.

What if my solar is AC-coupled and not visible in the inverter API?

Then tariff setup and solar visibility are separate issues.

The tariff can still describe grid import prices. Solar readings depend on whether the connected devices and meters actually report solar generation to 1app.energy.

Is this only for British Gas customers?

No. British Gas PeakSave is just a clear example.

The same day-specific setup can help with other fixed tariffs where the price depends on the weekday, weekend or a regular weekly pattern.

Final thought

Customers should not have to change supplier just because their energy app cannot describe a real tariff.

If a home has a Sunday cheap window, weekend pricing or a different weekday pattern, the app should let the customer enter that clearly and then use it carefully.

That is the direction 1app.energy is taking: clearer tariff setup, better whole-home context and supported automation only where the installation is verified and the customer enables it.

Check if your setup fits to start early-access onboarding.