Powerwall 2

Tesla Powerwall 2 is a 13.5 kWh AC-coupled home battery. Tesla’s current UK support material positions it as the model designed to add storage to an existing solar system. It has its own battery inverter and works alongside the property’s solar inverter rather than accepting a PV string directly.

Power and capacity

Tesla publishes 5 kW continuous on-grid power and 7 kW peak backup power. Energy capacity describes how much electricity the battery stores, while power describes how quickly it can supply a load. Neither figure alone establishes how long a home can run during an outage because the reserve setting and the connected loads also matter.

Tesla documents systems of up to ten Powerwall 2 units. A multi-battery design changes both stored energy and available power, but it also changes protection, connection and physical-space requirements. The commissioned system rating, rather than the number printed on one enclosure, is the figure relevant to the DNO application.

Solar, backup and controls

Because Powerwall 2 is AC-coupled, it can work with major solar inverter brands and can also charge from the grid where the operating mode and electricity arrangements allow it. Backup requires a Backup Gateway 2 to detect a network outage, isolate the supported electrical installation and coordinate island operation. The circuits connected behind that arrangement determine whether backup covers all loads or a selected distribution board.

The Tesla app provides energy-flow monitoring, operating modes and backup-reserve control. Internet access enables remote monitoring and over-the-air software updates. If connectivity is lost, Tesla says Powerwall continues in its last operating mode and can still provide backup, but extended disconnection may affect warranty cover.

Siting and current status

The enclosure measures 1,150 by 753 by 147 mm, weighs 114 kg and is documented for operation between -20°C and 50°C. Tesla’s UK support pages continued to describe Powerwall 2 alongside Powerwall 3 at this review, so it is recorded as current rather than superseded. Powerwall 3 is the integrated-solar model, while Powerwall 2 remains the explicitly documented retrofit product.

Tesla publishes a ten-year warranty. The warranty supplied with the system controls the exclusions, operating conditions and retained-capacity terms, so the headline duration is not the complete warranty specification.

Related entries

• Tesla
• Backup Gateway 2
• Powerwall 3
• AC-coupled battery architecture
• Whole-home backup changeover
• Battery firmware and cloud dependency