Economy 7, Smart Meters & Solar UK

Still on Economy 7? Here's how switching to a smart meter changes things when you add plug-in solar — and why you should do it before panels arrive.

Why Economy 7 and Solar Don't Mix Well

Economy 7 gives you cheap electricity for 7 hours overnight (typically 00:30–07:30) and a higher rate for the remaining 17 hours. It was designed for storage heaters and immersion water tanks that charge overnight.

The problem for solar owners: your panels generate during the day, when you're on Economy 7's expensive rate. The solar offsets that expensive import, which is actually a bigger saving per kWh than it would be on a flat tariff. That sounds good — but Economy 7's daytime rate is typically 30%+ higher than a standard flat rate, meaning you're overpaying for any daytime electricity your solar doesn't cover.

Unless you use very little daytime electricity beyond what solar provides, you're almost certainly better off switching.

The Smart Meter Switchover

When you replace an Economy 7 meter with a SMETS2 smart meter, you're also changing your meter configuration from a two-register (day/night) setup to a single import + export setup. This enables:

Flat-rate tariffs — a single unit rate for all import, regardless of time
Modern ToU tariffs — like Octopus Flux or Agile, which are designed for solar owners and offer better value than Economy 7
Export recording — Economy 7 meters generally can't record export at all
Half-hourly data — fine-grained usage visibility for optimising self-consumption

What About Storage Heaters?

If you're on Economy 7 because you have storage heaters, switching meter type doesn't mean you can't charge them overnight. A smart meter with a ToU tariff still gives you cheap overnight rates — often cheaper than Economy 7's night rate. Set your storage heater timers to match the off-peak window.

If you're upgrading to gas central heating or a heat pump, the Economy 7 consideration becomes irrelevant.

The Switch Process

Contact your supplier and request a SMETS2 meter installation to replace your Economy 7 meter
At the same time, ask to switch to a tariff suitable for solar — either a flat rate or a ToU tariff like Flux
The engineer visit replaces the old meter with a SMETS2 unit — same wall position, similar physical size
Once installed, ask for the export register to be enabled
Install your plug-in solar and apply for SEG payments

The entire switch typically costs nothing and takes 2–4 weeks to schedule.

Will I Save More or Less?

This depends on your usage pattern. Model it before switching:

If you use most electricity at night (storage heaters, overnight EV charging, night-owl lifestyle): Economy 7's cheap night rate is valuable. A solar-friendly ToU tariff might give you equivalent or better overnight rates. Compare specific rates before switching.

If you use most electricity during the day: you're currently paying Economy 7's expensive daytime rate. Switching to a flat rate at ~24p/kWh plus solar offsetting daytime import is almost certainly cheaper.

Run the numbers: check your last 3 months' bills. Note how much is charged at the day rate vs night rate. Then compare what you'd pay on a flat rate with the same consumption, minus estimated solar savings. Use our calculator for the solar portion.

Worked example: Economy 7 household with plug-in solar

Retired couple, three-bed detached in Yorkshire, storage heaters upstairs, electric water heating overnight, roughly 8,500 kWh/year total consumption. Recently installed an 800W plug-in solar kit.

Before solar (annual):

Economy 7 day rate 28p × 4,200 kWh = £1,176
Economy 7 night rate 12p × 4,300 kWh = £516
Standing charge (365 × 62p) = £226
Total: £1,918

After solar (annual):

Solar generation: 750 kWh, ~85% self-consumed (high home occupancy) = 638 kWh
All solar displaces day-rate consumption (panels do not generate at night)
New day-rate import: 4,200 − 638 = 3,562 kWh × 28p = £997
Night rate unchanged: £516
Standing charge unchanged: £226
Total: £1,739
SEG income (112 kWh × 5.6p): +£6.30 credit
Net saving: £185/year

Notice: the saving is £185 not £180 despite an 800W kit generating 750 kWh — because self-consumption is high (retirees home during the day) and day-rate is expensive. This is the ideal Economy 7 solar profile.

When switching off Economy 7 makes sense

If your storage heaters and immersion are the main drivers of night usage, staying on Economy 7 is right. But three profiles benefit from switching to a flat rate + plug-in solar:

Empty nesters whose kids moved out but who kept the tariff — night usage has fallen but the day rate is still punishing
Households that swapped storage heaters for a heat pump or gas — the tariff's whole rationale is gone
Home-working single-income households — daytime usage now dominates, and Economy 7's 28p day rate is significantly above the flat 24.5p cap

Run the numbers using the savings calculator or the Ofgem cap comparison. If your day-rate consumption is >65% of total and rising, switching is usually worth it.