Portable Power Station vs Home Battery: Which Do You Need?

What each product actually is

A portable power station is a self-contained box with LFP cells, an inverter and AC sockets. You plug appliances directly into it. Typical UK models range from ~1kWh (EcoFlow DELTA 3 Classic, Jackery 1000 v2, Anker SOLIX C1000) up to ~4kWh (EcoFlow DELTA Pro 3). No installer, no paperwork, no grid connection.

An installed home battery is a wall- or floor-mounted unit wired into your consumer unit by an MCS-registered electrician, with a DNO (Distribution Network Operator) G99 notification for anything above 3.68kW output. Typical UK sizes are 5kWh, 10kWh and 13.5kWh (Tesla Powerwall 3, EcoFlow PowerOcean, Anker SOLIX X1, Fogstar). It talks to your smart meter or an energy app and charges/discharges automatically based on your tariff.

VAT: 20% vs 0% until 2027

Portable power stations are consumer electronics and carry the standard 20% VAT. They do not qualify for the 0% VAT relief on energy-saving materials.

Installed home batteries qualify for 0% VAT under HMRC's VAT Notice 708/6 until 31 March 2027, after which the rate reverts to the 5% reduced rate — not 20%. The relief applies to hardware and labour under a supply-and-fit contract with a VAT-registered installer, covering standalone, retrofit and hybrid solar-plus-storage installs.

Install, MCS and DNO

Portable: none. Unbox, charge, plug in.

Installed: MCS certification is normally needed for the installer if you want access to the best Smart Export Guarantee tariffs. Any system with continuous AC output above 3.68kW requires DNO approval (G99) BEFORE install; anything at or below 3.68kW can typically be notified after the fact under G98. This is a real timeline — G99 approval often takes several weeks and shapes when installers can slot you in.

Backup: sockets vs whole home

Portable: backs up only what you plug directly into the AC sockets. You have to physically move appliance leads. Perfectly good for a fridge, router, phone charging, a couple of lamps and a laptop through a short outage. Wattage is capped by the inverter (typically 1,500–3,840W continuous).

Installed + backup gateway: can back up the entire consumer unit, or a chosen sub-circuit, automatically. Whole-home backup requires a battery with enough continuous output to cover inrush loads (kettles, ovens) — the Tesla Powerwall 3 (up to 11.04kW), Anker SOLIX X1 and similar are common picks. EPS/backup switchover times vary; where a manufacturer doesn't publish a figure, we don't invent one.

Tariff-shifting: manual vs automatic

Portable: you can manually charge overnight from a wall socket and run appliances off it during the day, but you're limited to whatever's plugged into the box. Anything hardwired (immersion heater, oven, EV charger) can't be shifted. It's fiddly and usually not worth doing at scale.

Installed: charges automatically during the cheap window of your smart tariff (Intelligent Octopus Go, Cosy, EV tariffs — often around 7p/kWh in mid-2026) and discharges through your consumer unit during the ~28p/kWh evening peak. This is where the payback comes from and it's what the OffPeak calculator actually models.

Export: SEG vs nothing

Portable: cannot export to the grid at all. No SEG income.

Installed with solar: qualifies for Smart Export Guarantee payments. Suppliers pay for exported solar energy, and some now meter to ensure only solar-origin export is paid — not grid-charged 'brown' electricity being resold. Rates vary from ~1p to 15p+ per kWh.

Capacity and £/kWh

Portable, based on UK July 2026 retail: typically 1–4kWh, at roughly £390–£980 per usable kWh (£799 for a 2kWh DELTA 3 Max = ~£390/kWh; £999 for a 1kWh Anker SOLIX C1000 = ~£980/kWh).

Installed, fitted: typically 5–13.5kWh (larger with stacking), at roughly £450–£600 per usable kWh fitted (e.g. £4,500 fitted for 5kWh ≈ £900/kWh at the small end, dropping to ~£450–£600/kWh at 10–13.5kWh). The bigger the installed system, the lower the £/kWh — the opposite of the portable market.

So which do you need?

Buy a PORTABLE if: you want blackout insurance for a fridge, router and phones; you camp or work off-grid; you rent and can't install fixed kit; or you just don't want an installer in the house.

Buy an INSTALLED battery if: your goal is to cut your electricity bill via a smart tariff; you want automatic whole-home backup; you have or plan solar and want to maximise self-consumption and SEG; or you have an EV and want to shift as much load as possible into the cheap overnight window.

The two products don't really overlap. If you're trying to decide between them because of price, the honest answer is that a £799 portable and a £7,000 fitted battery are solving different problems — pick by what you actually want to do with it.