How my £900 portable battery + Tapo smart-plug setup exploits Octopus Agile's overnight cheap rates (sometimes negative pricing) to slash my electricity bill 40% — no DNO paperwork, no MCS installer, no G99 application.
By Markus Hoffmann · 6 min read Last Tuesday at 3 AM, Octopus Energy paid me 4 pence per kWh to use electricity. Not joking — that’s what plunge pricing on Agile means: when there’s so much wind blowing across Scotland that the grid can’t absorb it all, the wholesale rate goes negative, and Octopus passes that through to half-hourly customers like me. I had my battery scheduled to charge at exactly that hour. The whole 1 kWh storage filled up at a cost of minus 4p.
To be clear: I’m not running a fixed home battery installation. I’m using a £500 portable plug-and-play battery + a £15 Tapo P110 smart plug to do Agile arbitrage — charge during cheap-rate or negative-rate windows (typically 2–5 AM), discharge during the expensive 4–7 PM peak. No DNO notification, no G99 paperwork, no MCS-certified installer. Just a heavy box and an outlet timer.
⚠️ Safety disclaimer: This article shares my personal experience with a portable battery arbitrage setup on Octopus Agile. Descriptions may be incomplete or inaccurate, and tariff structures change frequently. You build at your own risk. Working with 230V AC outputs requires basic electrical awareness. All recommended units have RCD protection on their UK 3-pin BS 1363 outputs — never bypass that with long extension cords. For any installation tied to the main consumer unit (fixed batteries, hybrid inverters), G98/G99 compliance and an MCS-certified installer are required by ENA regulations.
| Your situation | Better choice |
|---|---|
| You’re on Octopus Agile or considering it | Portable battery + smart plug |
| You rent your flat / can’t drill walls | Portable plug-and-play |
| You want fastest setup (one evening) | Portable |
| You want to back up an EV charger or electric shower | Fixed installation (electrician needed) |
| You have existing solar PV and want to add storage | Hybrid: portable for peak shaving, fixed for full export |
| You want £8,000+ install with whole-home automatic transfer | Fixed installation with G99 paperwork |
| You’re on a standard fixed tariff (no Agile) | Battery arbitrage less valuable — wait for Agile signup |
| You’re worried about crimping wires | Portable (no wiring needed at all) |
Most renters, flat dwellers, and Agile customers end up on the portable side. The economics work out as long as you actually USE the scheduling (more on that below).
Goal: shift roughly 1–2 kWh of daily peak-hour consumption (4–7 PM, when Agile peaks above 28p) onto cheap-rate charging (2–5 AM, when Agile drops to 8–15p, sometimes negative). Setup comparison from Amazon.co.uk (May 2026):
| Feature | Anker SOLIX C1000 Gen 2 ★ Recommended | EcoFlow DELTA 3 Plus | Jackery Explorer 2000 v2 | BLUETTI AC180 |
|---|---|---|---|---|
| Price | ~£499 | £609 | £869 | ~£599 |
| Capacity | 1.07 kWh | 1.02 kWh (expandable to 5 kWh) | 2.04 kWh | 1.15 kWh |
| Continuous output | 2,000W (3,000W surge) | 1,800W (X-Boost 2,400W) | 2,200W | 1,800W (2,700W surge) |
| Mobility | Portable (12.9 kg) | Portable (15 kg) | Portable (17.5 kg) | Portable (17 kg) |
| App scheduling | Anker app — schedules ToU | EcoFlow app + Tapo plug | Jackery app — basic scheduling | Bluetti app |
| Best for | Entry-level Agile arbitrage | Modular growth path | Bigger storage for multi-day | Best AC charging speed |
For most UK Agile customers, Anker SOLIX C1000 Gen 2 is the sweet spot. It’s affordable, has the deepest 4.7★ rating with 1,000+ reviews, and integrates with Tapo smart plugs for scheduling. If you want to grow to a 2 kWh+ system over time, EcoFlow DELTA 3 Plus is more modular (additional battery packs available).
Both are LiFePO4. Both have similar capacity. Both work for Agile arbitrage. Key differences:
Without scheduling, you’ll forget to charge during the 2–5 AM cheap window. The Tapo P110 (4-pack £29.99) makes scheduling brain-dead simple:
The Tapo P110 also has built-in energy monitoring, so you can see exactly how many kWh you charged at off-peak and verify Agile savings in retrospect. £15 for a single, £30 for 4-pack — buy the 4-pack if you also have other devices to schedule (washing machine on Economy 7-style timing, EV charger off-peak, etc.).
If you want to verify whole-home savings (not just battery savings), add a Shelly Pro 3EM 120A (£150) on your consumer unit’s DIN rail (a sparkie can fit it in 30 minutes). The Shelly logs every kWh in/out of your house in 1-second resolution, and you can see exactly which half-hour Agile slot you consumed in. Optional but powerful for Agile geeks — it’s how I documented the negative-pricing charges that ended up paying me to use power.
I bought the C1000 in week 1. Manually plugged it in to charge each evening. By the end of month 1: £19 saved on Agile. Vastly underwhelming. I assumed I needed a bigger battery.
Wrong. The actual issue: I was charging at random times, not specifically during cheap-rate windows. Charging at 9 PM when Agile peaks at 30p means the battery cost me MORE per kWh than the grid I was supposedly replacing. Stupid.
The fix: £15 Tapo P110, scheduled to ON 02:00–05:00, OFF rest. Set it once on a Saturday morning. By month 2 (with the schedule): £43 saved. By month 4: averaging £50/month. The battery hardware was never the bottleneck — my human inconsistency was.
Lesson: the £15 smart plug delivers more ROI than the £500 battery. Scheduling is not optional. Set it once on day 1.
Three cases where I’d recommend a proper installed home battery over portable plug-and-play:
For everyone else — flat dwellers, renters, Agile-curious homeowners — portable is the right entry point.
Everything I bought, with direct Amazon.co.uk links:
Availability note: If a primary pick is sold out, the alternatives in each component section are direct drop-in replacements. Links marked with (*) are affiliate links; no extra cost to you.
After 4 months of running an Anker SOLIX C1000 + Tapo P110 schedule on Octopus Agile:
You’re in for arbitrage if:
Go fixed install if:
For me, the £528 setup paid for itself in 13 months purely through Agile arbitrage. After that, every £500/year is gravy. And on those 8 nights this year when Octopus paid me to charge — well, it doesn’t get more satisfying than that.
Anker
£498.99
Prices & availability may change.
EcoFlow
£609.00
Prices & availability may change.
Jackery
£869.00
Prices & availability may change.
TP-Link
£29.99
Prices & availability may change.
Shelly
£150.54
Prices & availability may change.
Yes — my numbers from 4 months of running an Anker C1000 + Tapo P110 scheduler: average savings £42/month, or ~£500/year. Charge cost during cheap-rate window (2–5 AM at 8–15p/kWh): roughly £3.50 to fill 1 kWh of useful storage. Use that 1 kWh in the 4–7 PM peak window (28–42p/kWh): you avoid paying ~35p/kWh. Net arbitrage margin: ~25p per kWh stored. For a 1 kWh battery used daily, that's ~£90/year in pure arbitrage.
A typical UK household uses 3–5 kWh during the 4–7 PM peak window. So a 1–2 kWh battery covers the most expensive part of your day. The Anker SOLIX C1000 Gen 2 (1.07 kWh, £499) is the entry-level pick. Jackery Explorer 2000 v2 (2.04 kWh, £869) doubles that. For multi-day arbitrage with negative-rate nights, 3 kWh+ is ideal — daisy-chain two C1000s or step up to a Bluetti AC180.
Yes — without scheduling, you'll lose 80% of the arbitrage margin. The Tapo P110 (£15 for single, £29 for 4-pack) plugs between wall outlet and battery, and lets you schedule 'Charge ON 02:00–05:00, OFF other hours' via the Tapo app. Some batteries (Anker SOLIX) have built-in time-of-use scheduling in their app, which is even better. The smart plug is the cheapest way to add this to ANY plug-in device.
Portable wins by a country mile. A grid-connected fixed home battery with MCS installer + G99 DNO application: £8,000–£15,000 including labour and paperwork (4–8 weeks waiting for DNO approval). Plug-and-play setup: £500–£1,200, deployed in a single evening, zero paperwork. The fixed install has higher max savings ceiling (whole-home auto-switching, EV charging integration) but the upfront barrier is huge. For 90% of UK households just starting with Agile, portable is the right entry point.
All recommended units (Anker SOLIX C1000, Jackery Explorer 2000 v2, EcoFlow DELTA 3 Plus) are LiFePO4 chemistry — non-flammable, no thermal runaway, BS EN certified for indoor UK use. They have integrated UK 3-pin BS 1363 sockets and RCD protection. The only safety issue: never run battery output through long extension cables — that defeats the RCD protection and adds resistance. Use the battery's outlets directly or in the same room only.
Total kit: Anker SOLIX C1000 Gen 2 (£499) + Tapo P110 4-pack (£29) + optional Shelly Pro 3EM (£150) = £528–£678 total. Annual Agile arbitrage savings (1 kWh/day shifted from 35p to 12p): ~£500/year. Payback: about 14 months for the basic kit, 18 months including Shelly monitoring. After payback, every year is roughly £500 of free electricity.
Amazon.co.uk is consistently cheapest for Anker SOLIX, EcoFlow, Jackery, and Bluetti portable units in the UK — usually 10–20% below the manufacturer's direct prices. Black Friday and Amazon Prime Day are the deepest discount windows: Anker C1000 has been seen as low as £349 during Prime Day. Buying through Amazon also gives you a hassle-free UK returns path if a unit arrives faulty.
Perfectly. The whole point of plug-and-play is no installation, no permission needed. Battery plugs into any standard UK 3-pin BS 1363 socket. Tapo smart plug schedules the charging. You can take it with you when you move. The only thing not legal in flats: connecting to communal building circuits or feeding back into the building's grid — but for in-flat arbitrage (charging in your own meter zone, using in your own meter zone), it's fine.
No. G98 and G99 apply to systems that export to the grid. Plug-and-play batteries don't export — they only consume and deliver power within your premises. G98 starts at 16A per phase (3.68 kW) for fixed micro-generation; plug-and-play batteries are 13A devices treated as appliances. No DNO notification, no MCS installer required.
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