Enphase IQ Battery 5P: UK price, specs and warranty

How the IQ Battery 5P is different

Most home batteries either share a hybrid inverter with the solar panels or have one large inverter of their own. The IQ Battery 5P has six small IQ8D-BAT microinverters built into the unit, so it plugs into the home’s alternating-current wiring and never touches the panels’ direct current. Enphase calls it a fully integrated AC-coupled system. In practice that means:

• Any existing solar system can stay as it is. Nothing about the panels or their inverter changes, which is why it is a common choice for adding a battery to existing solar.
• Capacity comes in 5 kWh steps. Two units make 10 kWh; Octopus’s solar package fits one or two, and its battery-only range uses two for its 10 kWh option.
• It suits homes that already have Enphase microinverters on their panels, because the whole system is monitored in one Enphase app.

The trade-off is efficiency on stored solar. Enphase’s UK datasheet gives 90% round-trip efficiency measured AC to AC and 96% on the DC side, because solar energy is converted to AC by the panel’s inverter, back to DC to charge the battery, and to AC again to use. A DC-coupled battery avoids one of those conversions. See AC vs DC coupled batteries.

What an Enphase battery costs

Octopus’s 5 kWh battery-only price works out at about £790 per kWh. The official median for MCS-certified batteries under 6 kWh fitted in 2025/26 was £1,300 per kWh, and £890 per kWh for 6 to 11 kWh. Small batteries always cost more per kWh, because installation, cabling and commissioning cost much the same whatever the size. Octopus’s solar package with Enphase starts about £1,270 above its Fox ESS equivalent (£9,187 against £7,915 with 4 panels), reflecting panel-level microinverters and a different battery.

What 3.2 kVA and 5 kWh mean day to day

Power. One unit delivers 3.2 kVA continuously, about 13.9 A. That is enough for a kettle or an oven, but not both at full power at once, and not an electric shower, which typically draws 7.5 to 10.5 kW. Two units double the power to 6.4 kVA.

Charging in the cheap hours. Enphase’s UK datasheet gives output ratings but no separate charging rate, and it says charging power is reduced below 15°C, which in a UK winter covers most unheated garages and outside walls. If you plan to fill the battery in a short cheap window, such as Octopus Flux’s three hours from 2am to 5am, ask the installer how long a full charge takes in winter.

The network limit. On its own, one IQ Battery 5P at 13.9 A sits under the G98 limit of 16 A per phase, so the installer can connect and notify the network afterwards. Added to an existing solar inverter, or doubled up to 10 kWh, the combined rating will almost always exceed 16 A, which means a G99 application before connection and sometimes an export limit.

In a power cut the 3.2 kVA limit decides what can run. The guide to backup in a power cut tabulates typical appliance ratings against the backup power of popular systems.

The warranty and its conditions

Enphase’s UK limited warranty, effective 5 September 2023, covers the IQ Battery 5P for 15 years from activation or 6,000 discharged cycles, whichever comes first, and promises at least 60% of nameplate capacity throughout. At one cycle a day, 6,000 cycles is about 16 years, so the 15-year term normally ends first; a battery doing 1.5 cycles a day would use its 6,000 cycles in about 11 years.

The 60% floor is lower than Tesla’s 80% after 10 years or Fox ESS’s 70% after 10 to 12, so the longer term buys less protection against fade in the later years. Compare warranties on all three numbers in how long batteries last.

The conditions are specific:

• Sold by Enphase or an authorised reseller. The warranty only applies to products sold that way and installed in the UK.
• Registered within 45 days. The warranty does not apply if the battery is not registered with Enphase within 45 consecutive days of activation. Ask your installer to confirm it has been done.
• Always online. The battery must stay connected to the internet for the whole warranty period, except for interruptions outside your control, so Enphase can diagnose faults and send firmware updates.
• Kept up to date. Damage that current firmware would have avoided is excluded.
• Transfer on sale. A buyer of your home keeps the warranty only by submitting a Change of Ownership Form and paying Enphase’s transfer fee within 30 days of the transfer, with the battery still at the original address.
• The rest of the system. The IQ Gateway, current transformers and communications kit are warranted for 5 years, and problems caused by another manufacturer’s component in the solar system are excluded.

Enphase repairs, replaces or refunds the current market value at its discretion. Under the Consumer Rights Act 2015, your first route for a faulty product is the seller, which for most homes is the installer.

When an Enphase battery is the right choice

It suits homes with existing solar that is working well, homes with Enphase microinverters, and smaller homes where one or two 5 kWh units match the evening use. It is less suited to a new solar and battery system where a single hybrid inverter or an all-in-one with a solar inverter built in, such as the Tesla Powerwall 3 or a Fox ESS EVO, converts stored solar more efficiently.

When you compare quotes, check how many units are included, whether backup is part of the system, the Gateway and monitoring hardware, and who registers the battery with Enphase. Two or three battery storage quotes set side by side on those points will show you what a fair price for your home looks like.