Foxstar vs Tesla Powerwall: Which Battery Is Right for Your Home?

Why Battery Storage Matters

A home battery transforms how you use solar energy. Without one, surplus solar electricity is exported to the grid at up to 25p/kWh (SEG). With a battery, you store that surplus and use it in the evening when grid electricity costs 24.67p/kWh. The difference is significant: most households increase solar self-consumption from 40% to over 80%.

Foxstar and Tesla Powerwall are the two most commonly installed batteries in UK homes. As installers of both, we can give an honest, unbiased comparison based on real installations.

Foxstar Overview

Foxstar is a UK-founded battery company with a strong track record in the residential and commercial market. Their systems are manufactured in China and distributed through UK installers with strong local support.

• Capacity options: Foxstar 13.5kWh (£6,942 installed), plus modular options from 2.6 kWh, 5.2 kWh, 9.5 kWh, stackable up to 19.2 kWh
• Warranty: 12 years (or 6,000 cycles) for Foxstar 13.5kWh
• Software: Foxstar app with detailed monitoring, time-of-use tariff optimisation, and EV charge scheduling
• Inverter: Hybrid inverter handles both solar and battery — one unit for the whole system
• Output: 3.6kW/5kW continuous output
• Weight: 174kg
• IP rating: IP65 (weatherproof)
• UK company: Strong UK presence with open API for third-party integrations
• Price: Typically £2,800–£3,800 for a 5.2 kWh system installed; Foxstar 13.5kWh from ~£6,942 installed
• Retrofit: Works with existing solar systems via AC coupling

Tesla Powerwall Overview

The Tesla Powerwall is the most recognised home battery globally. The current model is the Powerwall 3, which combines a solar inverter and battery into a single unit.

• Capacity: 13.5 kWh (Powerwall 3) — almost three times a standard Foxstar unit
• Warranty: 10 years (unlimited cycles)
• Software: Tesla app with storm watch, time-based control, and backup mode
• Inverter: Powerwall 3 includes an integrated solar inverter
• Price: Typically £7,500–£11,500 installed — a significant premium
• Continuous output: 11kW continuous power output
• Weight: 132kg
• IP rating: IP67 (fully weatherproof)
• Retrofit: Powerwall 3 is designed for new solar installs; Powerwall 2 for retrofit

Head-to-Head Comparison

Feature	Foxstar 13.5kWh	Tesla Powerwall 3
Usable capacity	13.5 kWh	13.5 kWh
Installed price	~£6,942	£7,500–£11,500
Warranty	12 years	10 years
Continuous output	3.6kW/5kW	11kW
Weight	174kg	132kg
IP rating	IP65	IP67
Backup power	Optional add-on	Built-in
App quality	Very good	Excellent
UK support	Strong UK base, open API	Through Tesla installers

Which Should You Choose?

Choose Foxstar if: You want excellent performance at a lower price point. A 5.2 kWh Foxstar covers most households' evening energy use and costs roughly a third of a Powerwall 3. You can always add a second unit later if needed.

Choose Tesla Powerwall if: You have high electricity consumption, want backup power during outages, or value the brand and app experience and have the budget. The 13.5 kWh capacity suits homes with heat pumps and EV chargers where evening loads are higher.

Both systems are excellent choices. For most 3–4 bed homes with a typical solar array, a Foxstar 5.2 kWh provides the best value. Larger homes with a heat pump and EV may benefit from Powerwall's larger capacity.

Combining with Solar and Heat Pumps

Both batteries work seamlessly with solar panels. When paired with a heat pump, the battery can be programmed to store cheap off-peak electricity (e.g. Octopus Flux or Agile tariff) overnight and use it to run the heat pump during expensive peak hours.

This combination — solar panels, battery, and heat pump — is the most efficient whole-home energy system available today. See our guide on solar panels and heat pumps combined for the full picture.

We install both systems across St Austell, Newquay, Truro, and across Cornwall. Book a free consultation to discuss which battery suits your home.