13.5 kWh home storage with an integrated solar inverter.
Tesla Powerwall 3 combines battery storage, high on-grid power capability, solar inputs and app-based energy control. It can suit new solar-and-storage projects and compatible existing-solar applications when the complete system is designed correctly.
Energy capacity and power are both important.
Tesla lists 13.5 kWh energy capacity and up to 11.04 kW on-grid or backup power for Powerwall 3, depending on local conditions. The integrated solar inverter provides three MPPT inputs, while the Gateway manages site metering, grid isolation and backup operation.
Integrated solar inverter
New solar strings can connect directly where the array design, voltage and current limits suit the exact installation.
Existing-solar route
Tesla states Powerwall 3 can also be added to existing solar, subject to supported systems and territory-specific limitations.
Expansion
Powerwall 3 Expansion adds 13.5 kWh energy capacity per expansion unit, extending runtime without treating every unit as another complete inverter.
What does 13.5 kWh mean at home?
Capacity determines the energy window; the high power rating determines which simultaneous loads may be supported. Reserve settings and conversion losses reduce the simple theoretical runtime.
Illustrative examples
- Around 13.5 hours at a steady 1 kW load before allowances
- Around 6.75 hours at a steady 2 kW load
- Around 4.5 hours at a steady 3 kW load
- A 7 kW EV charger could consume the full nominal energy in under two hours
Figures are simple energy illustrations, not guaranteed runtime. Allow for battery reserve, conversion losses, temperature, ageing and changing household demand.
High power does not mean unlimited outage duration.
- Backup Gateway detects an outage and isolates the property
- Available runtime depends on charge and connected demand
- Large motors and compressors have starting-current requirements
- Solar may recharge the battery during a daytime outage where conditions permit
- Backup reserve can be adjusted in the Tesla app
- Whole-home and partial-home designs require site-specific assessment
Compatibility point
Tesla states Powerwall 3 can be expanded with other Powerwall 3 units but cannot be added to a Powerwall 2 system.
The Gateway, electrical panels, metering, DNO position and solar design are part of the project—not optional afterthoughts.
Official reference: Tesla UK — How Powerwall Works and Powerwall System Design.
Survey the loads before promising the backup.
Assess
Supply, solar, usage, tariffs and outage priorities.
Design
Powerwall, Gateway, PV inputs and electrical configuration.
Install
Equipment, protection, metering and communications.
Commission
Tesla app setup, backup test, documentation and handover.
Is Powerwall 3 the right 13.5 kWh system for your home?
Let us compare its power, storage, solar inputs and backup capability with your actual electricity profile.