Home Battery Storage

No. A battery pays back two ways. With solar, it captures surplus you'd otherwise export at 5-15p and lets you use it at 28-30p later, lifting self-consumption from around 40% to 70-80%. Without solar, it charges from a smart time-of-use tariff in a cheap overnight window and runs your home through the evening peak. Both work. The right answer depends on your tariff and when you actually use electricity. See our battery worth-it guide for the full maths.

Any tariff with a meaningful gap between off-peak and peak rates. In our 2026 Big 6 comparison, off-peak import runs from around 7p to 14p on tariffs that publish a national unit rate. Some battery-focused plans price their off-peak window as a percentage of the day rate in your region instead, so the figure depends on where you live. Peak import typically sits around 25-30p. The Energy Saving Trust maintains a neutral overview of time-of-use tariffs. The differential matters more than the supplier name. We size your battery against your chosen tariff so the daily cycle pays back.

It can, on either brand. Tesla Powerwall 3 installs include the Backup Gateway 2, which switches your consumer unit to battery power and keeps the whole home running through an outage. Fox ESS systems are grid-tied as standard, meaning they pause with the grid under G98/G99 anti-islanding rules, and can add the same cover with the optional Whole-Home Backup (EPS) upgrade. With the upgrade you choose how much charge to hold in reserve for cuts; that reserve does not cycle day to day, so a bigger reserve means smaller daily savings.

Most UK 3-bed homes suit a 10 kWh battery. With an EV, you usually charge the car from the off-peak tariff overnight rather than the battery, since both use the same cheap window. A 10-13 kWh battery covers household use. With a heat pump, we often size 13-20 kWh to bank cheap-rate power for evening heating peaks, often paired with a heat pump tariff. Sizing happens at quote stage.

Yes. The battery and inverter you install today work with panels added later. Tesla Powerwall 3 has a built-in solar inverter; Fox ESS uses an H1 hybrid inverter ready for solar input. At add-on time you pay for panels, mounting, and MCS paperwork for the Smart Export Guarantee. Mention solar plans before install so we size the inverter correctly.

No. The Powerwall 3 has a hybrid inverter built in, with three MPPT trackers and support for up to 20 kW of solar input, so it runs your solar array directly with no separate inverter box on the wall. That also makes it a tidy choice when an existing solar inverter is nearing end of life: the Powerwall replaces it and adds 13.5 kWh of storage in one unit.

A Fox ESS H1 single-phase hybrid inverter, sized at 3.7, 5.0 or 6.0 kW to suit your setup, with up to a 10-year warranty. It manages the battery and any solar panels together, and pairs with Fox ESS EP6 (5.76 kWh) and EP12 (11.52 kWh) battery modules. For AC-coupled retrofits alongside an existing solar inverter, we confirm the right configuration as part of your fixed online quote.

Modern lithium iron phosphate (LFP) batteries are rated for around 6,000 charge cycles, which works out to roughly a decade of cycling once a day. The standard manufacturer warranty is 10 years and guarantees the battery will hold at least 70-80% of its original capacity at the end of that period. After the warranty most batteries continue running with reduced capacity rather than failing outright. UKEM adds a 2-year workmanship warranty on top of the manufacturer cover.

Standalone home battery installs typically run from around £4,000 (Fox ESS EP6 at 5.76 kWh) up to £12,000+ (Tesla Powerwall 3 at 13.5 kWh with whole-home backup). The price covers the battery, hybrid inverter where required, isolators, wiring, commissioning, MCS paperwork and DNO notification. A retrofit to existing solar takes around a day. Get a fixed, personalised price through our online quote tool.

Most battery-only installs take around a day on site. No scaffolding, no roof access, no DNO solar generation application. The engineer mounts the battery (typically in a utility room, garage, or outside), wires it into your consumer unit through an isolator, commissions the system, and walks you through the app. Quote to install is usually 3-5 days for a standard retrofit. Powerwall 3 installs add around half a day for the included Backup Gateway and circuit reconfiguration.

Yes. Home batteries qualify for 0% interest finance over 12 to 24 months with a 25% deposit, or longer terms up to 15 years from 9.9%APR Representative with no deposit, subject to status. Finance is through FCA-authorised lenders; UKEM Group is an Introducer Appointed Representative of Shermin Finance Limited. Many households align repayments with time-of-use tariff savings. See how our payment options are structured.

Roughly a full day of normal use. Ofgem's typical UK household uses about 7.5 kWh of electricity a day, so a 10kWh battery covers an evening peak, overnight and the next morning, while a 5kWh unit covers a typical evening. High-draw appliances shorten that: an electric shower or oven pulls 2-3 kWh in a single use. Heat pumps and EV charging need their own sizing maths.

No, not in most cases. Home batteries are normally installed under permitted development rights in England, Wales and Scotland, whether wall-mounted or floor-standing. The exceptions worth checking: listed buildings, conservation areas, and flats. Your installer handles the paperwork that does apply, the DNO (network operator) notification, as part of the job.

The main disadvantages are upfront cost, storage losses, gradual capacity fade and the space the unit takes up. Payback depends on the gap between your import rate and what you'd otherwise export or buy off-peak. Round-trip losses mean you get back roughly 90% of what you store. Capacity fades to around 70-80% by the end of a typical 10-year warranty. And a battery needs wall or floor space in a garage, utility room or outside.