Tariff Stacking: Combining Solar, Battery, and Smart Tariffs

What is tariff stacking?

Tariff stacking is the practice of layering multiple energy cost-saving and income-generating strategies on top of each other. Each layer captures value from a different source:

1. Solar self-consumption — using your own generation instead of importing (saves ~24p/kWh at the April 2026 price cap)
2. Battery self-consumption — storing surplus for evening use (saves ~24p/kWh)
3. Cheap grid charging — charging the battery overnight at 5.5–10p/kWh (saves vs 24p peak)
4. Premium export — exporting during peak hours at 15–32p/kWh (earns more than standard SEG)
5. VPP/grid services — earning from frequency response or demand events (extra £100–£400/year)
6. Diverter savings — hot water from surplus solar (saves 5–7p/kWh of gas)
7. EV smart charging — charging from surplus solar or cheap overnight rates

No single strategy delivers maximum value. The magic is in combining them.

The tariff stacking pyramid

Think of it as layers, each building on the one below:

Layer 1: Solar self-consumption (foundation)

Every kWh you generate and use directly saves you the full retail rate — ~24p/kWh at the April 2026 price cap. This is the most valuable layer because the saving per kWh is highest.

A 4kW system with 30–40% self-consumption rate uses roughly 1,200–1,600 kWh directly, saving £290–£384/year.

Layer 2: Battery storage

A battery increases self-consumption to 60–80% by storing daytime surplus for evening use. The additional 1,000–1,500 kWh shifted from export to self-consumption saves another £240–£450/year.

Layer 3: Smart import tariff

Moving to a time-of-use tariff (Octopus Go, Agile, Cosy) lets you charge the battery overnight at 5.5–10p/kWh instead of importing at 24p/kWh during the day. Annual saving: £150–£300 from the rate differential alone.

Layer 4: Premium export

Switching from a standard SEG rate (3.3–5.2p basic, up to 15p best fixed) to a time-of-use export tariff (Flux peak: 24–32p/kWh) increases export income. With a battery, you can shift export to peak hours. Additional annual value: £50–£200.

Layer 5: Grid services / VPP

Enrolling your battery in grid balancing services through a VPP scheme adds £50–£400/year depending on battery size and scheme type.

Layer 6: Diverter and EV

A hot water diverter saves £100–£250/year in gas/electricity. Smart EV charging from surplus solar or cheap overnight rates saves vs petrol and public charging costs.

Worked example: full stack

Household: 3,500 kWh annual consumption, 4kW solar, 10kWh battery, Eddi diverter, EV

Without solar (flat tariff at 24.5p/kWh — April 2026 price cap): £858/year electricity cost

With full tariff stack:

This is not hypothetical — UK households with optimised systems are achieving these numbers today. The system potentially generates more value than the electricity consumed, resulting in zero or even negative net energy costs.

Which tariff combinations work best?

Octopus Agile (import + export)

• Half-hourly pricing for both import and export
• Maximum flexibility and highest ceiling for savings
• Requires automation (Predbat) to capture full value
• Best for technically engaged users

Octopus Flux

• Three-rate import (cheap/standard/peak) + three-rate export
• Premium peak export rate (24–32p/kWh) is the key feature
• Simpler than Agile — fixed daily rate bands
• Good for battery owners who want export income without complex automation

Octopus Go + separate SEG

• Simple two-rate import (cheap overnight, standard daytime)
• Pair with the best available SEG for export
• Easiest to set up — fixed charge window, no daily optimisation needed
• Good baseline with less complexity

Intelligent Octopus Go

• Cheap overnight rate with flexible charging windows for EVs
• Combines well with solar + battery for whole-home optimisation
• Octopus may charge your EV during additional cheap periods beyond the core window

Setting up tariff stacking

Step 1: Install solar + battery

This is the foundation. Without generation and storage, the other layers have limited value.

Step 2: Switch to a time-of-use tariff

Contact Octopus (or your preferred supplier) to switch. No cost, no contract.

Step 3: Configure battery charging

Set up overnight charging windows on your inverter to match the cheap tariff period. GivEnergy, Sunsynk, and most hybrid inverters support this.

Step 4: Add automation (optional but valuable)

Install Predbat or equivalent for Agile price optimisation. This requires Home Assistant and some technical setup.

Step 5: Add a diverter

If you have a hot water cylinder, install an Eddi or iBoost to capture surplus after the battery is full.

Step 6: Enrol in a VPP

Check whether your battery brand offers VPP participation. Enrol for additional income.

The bottom line

Tariff stacking is where solar + battery economics really sing. Each additional layer captures value from a different angle — self-consumption, rate arbitrage, export timing, and grid services. The combined effect can reduce or eliminate your electricity bill entirely.

Start with the fundamentals (solar + battery + smart tariff) and add complexity as you gain confidence. The UK energy market is increasingly designed to reward flexible, intelligent consumers — and solar + battery owners are best positioned to benefit.

GivEnergy All-in-One 9.5kWh Battery

£5,500

capacity kwh

9.5

usable capacity kwh

8.6

chemistry

LFP

cycles

6000

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myenergi Eddi Solar Diverter

£185

max power w

3000

modes

power_divert,timed_boost

outputs

2

priority

configurable

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