Flux for solar owners

Flux is Octopus’s tariff built around a simple idea: buy electricity cheap, sell it back expensive. It’s designed for households with solar panels and ideally a battery too. Three time bands create a daily rhythm of cheap importing and premium exporting that can turn a home energy system into something genuinely cost-effective.

The three time bands

Flux splits the day into three periods with different import and export rates:

Off-peak (02:00 to 05:00): The cheapest import rate. This is when you charge your battery from the grid if solar didn’t fill it during the day. The rate is significantly below the standard Flexible tariff.

Day (05:00 to 16:00 and 19:00 to 02:00): A middle-ground rate for both import and export. During this period, your solar panels are generating and you’re either using that electricity, storing it or exporting it at a reasonable rate.

Peak (16:00 to 19:00): The most expensive import rate, but also the highest export rate. This is when grid demand is at its maximum. If you have a battery, this is when you discharge it. Either you avoid importing at the premium rate, or you actively export stored energy and get paid handsomely for it.

The exact rates change periodically and vary by region, but the structure stays the same. The relationship between the three bands is what makes the tariff work.

The buy-low-sell-high strategy

Here’s how a typical day looks for a Flux customer with solar and a battery:

Overnight: The battery charges from the grid at the cheap off-peak rate, topping up whatever the solar panels didn’t provide the day before.

Morning: Solar panels start generating. The house runs on solar power. Any excess charges the battery.

Midday: Solar generation peaks. The battery fills up. Excess solar exports to the grid at the daytime rate.

4pm to 7pm: The peak window. The battery discharges to power the house, avoiding expensive peak imports. If the battery has enough stored energy, it can export to the grid at the premium peak rate. This is where the real money is made.

Evening: The house switches back to grid power at the daytime rate. The cycle resets.

A well-sized battery (5kWh or more) running this pattern can significantly reduce or even eliminate net energy costs. Some households with larger solar arrays and batteries end up in net credit over the summer months.

Export payments compared to SEG

The Smart Export Guarantee (SEG) is the government scheme that requires suppliers to pay you for exported solar electricity. SEG rates from most suppliers are low. Typically 3-6p/kWh, sometimes less. You generate electricity, export it at whatever time of day and get a flat rate.

Flux export payments are structured differently and are generally more generous. The peak export rate (16:00 to 19:00) is substantially higher than any SEG rate. The daytime export rate is also competitive. Because Flux pays you more during the hours when the grid actually needs your electricity, the total export income can be considerably higher than a flat SEG payment.

The catch is that to maximise Flux export income, you need a battery. Without one, you’re exporting when the sun is shining (daytime rate) rather than when the grid needs it most (peak rate). A battery lets you store solar generation and export it during the premium window.

Do you need a battery?

Technically, no. You can join Flux with solar panels and no battery. You’ll benefit from cheaper overnight imports and earn the daytime export rate on any excess solar generation.

The tariff really shines with a battery, though. Without one, you can’t take advantage of the peak export window (your solar panels aren’t generating at 5pm in winter) and you can’t shift cheap overnight imports to avoid expensive peak consumption. The battery is what makes the time-shifting strategy possible.

If you have solar panels without a battery, compare Flux against Agile. Agile’s negative pricing events and very cheap overnight rates might actually work out better for solar-only setups, depending on your usage pattern and region.

Requirements

To join Flux, you need:

• Solar panels (any size, though larger arrays obviously benefit more)
• A smart meter (SMETS2, communicating with Octopus)
• An export meter (your smart meter usually handles this, but it needs to be registered for export)

A battery is strongly recommended but not strictly required. Octopus doesn’t mandate a minimum solar array size.

Standard Flux works with any battery system, giving you full control over when you charge and discharge. If you want Octopus to handle the battery scheduling automatically, Intelligent Octopus Flux is the upgraded version. It controls your battery directly, using weather forecasts to optimise how much off-peak electricity it draws from the grid versus how much it saves for peak export. Intelligent Flux requires a compatible battery from GivEnergy, Tesla, SolarEdge, Enphase, Huawei, Sigenergy or a handful of other approved brands. The import and export rates on Intelligent Flux are matched at every time of day, so you always earn the same per kWh as you pay for imports.

Typical savings and earnings

The numbers depend heavily on your solar array size, battery capacity, location and household usage. Rough ballpark for a 4kW solar system with a 5kWh battery in central England:

Summer months: The system may produce more than you use. Between avoided imports and export income, your electricity cost could be close to zero or even negative (net credit).

Winter months: Shorter days mean less solar generation. You’ll be importing more from the grid, but the cheap overnight rate keeps costs below what you’d pay on Flexible. Export income drops because there’s less surplus to store and sell.

Annual picture: A typical Flux household with solar and battery might save £200-500 per year compared to Flexible with standard SEG export payments. The saving comes from both reduced import costs and increased export income.

Flux vs Agile for solar owners

This is a common question. Both tariffs can work well with solar. The main differences:

Flux gives you predictable time bands and rates. You know what you’ll pay and earn at each time of day. The battery strategy is straightforward.

Agile gives you 48 price slots per day. More potential for savings on the best days (negative pricing, very cheap overnight), but more variability. You need automation or constant attention to optimise properly.

For most solar and battery owners, Flux is the simpler and more predictable option. If you’re technically minded and running home automation (Home Assistant or similar), Agile might squeeze out slightly more value, but it requires more effort.

Use the tariff comparison tool to compare rates for both tariffs in your area.