For a Murrieta homeowner adding Powerwall 3 to an existing Powerwall 2 installation, ask the installer to explain the controls for the finished system before relying on it during an outage. In Tesla’s documented mixed configuration, the switches do not all have the same scope.
This guide uses manufacturer and utility sources checked November 4, 2026. It is preparation guidance, not notice of a current shutoff or instructions to perform a shutdown or restart.
An older unit’s switch may have a different role
Tesla’s application note for adding Powerwall 3 to an existing Powerwall 2 system describes support beginning with software version 26.26, subject to its configuration requirements.
In that arrangement, Powerwall 3 becomes the site controller. The note says its On/Off switch controls the entire system; each Powerwall 2 switch controls only that individual unit. The listed gateway or Backup Switch retains the islanding-controller and site-meter roles.
Do not assume that familiar behavior from an older installation applies after an upgrade. Have the installer confirm that this application note actually matches your equipment, software and completed configuration. It is not a universal instruction for every Powerwall installation, and it does not establish that every combination of older equipment is supported.
Request an updated handover explanation
Before an outage, ask for a simple equipment map and the manufacturer-approved owner instructions for the final installation. Suggested questions include:
- Which unit controls the combined system?
- Which controls affect one battery, and which affect the whole installation?
- Which circuits are included in backup after the upgrade?
- What should the homeowner do when an alert appears, and whom should they contact?
- Where are the current owner instructions and installer support details kept?
Record the answers with the equipment model list. Avoid using an old checklist that describes a system you no longer have. Do not experiment with switches during an outage to discover their effects; follow the instructions for your installed configuration and contact the installer when uncertain.
Our Murrieta app-access guide covers the separate task of giving household members appropriate access to monitoring.
Confirm readiness without equating battery count with protection
A mixed installation still needs a backup plan based on supported circuits and actual loads. PG&E’s general battery guidance explains why starting charge, household demand and available storage affect duration.
Ask the designer to document continuous output, appliance starting requirements, reserve settings and a runtime estimate with explicit assumptions. More equipment does not by itself establish that every circuit is supported or that the system will last through every interruption.
Ordinary grid-tied solar alone generally does not provide outage power. Solar recharge requires compatible backup equipment and suitable sunlight; it cannot replenish storage continuously overnight.
Keep SCE information separate from equipment controls
The City of Murrieta’s utility planning document identifies SCE as the electric utility serving the city. Confirm service at your own address and use SCE’s official outage-status page for current grid information.
A utility status notice does not tell you how an installer configured your home battery controls. Keep both the official outage link and equipment support information available.
Put support responsibilities in the PPA discussion
A qualifying no-upfront solar-plus-battery PPA can help eligible homeowners access backup-capable equipment while preserving cash. If an offer involves existing batteries, obtain written confirmation of compatibility, ownership permissions and who supports the combined installation.
The CPUC solar guide explains provider ownership and ongoing electricity payments. Review rate, escalator, term, battery fees, maintenance and transfer provisions, plus remaining utility costs. No upfront purchase does not mean free electricity, universal eligibility or guaranteed savings.
Bring the equipment list and proposed handover plan to the West Coast Alternatives homeowner journey for a discussion grounded in your actual installation.