Can I use a Tesla Powerwall 3 to add a battery to my existing Enphase, SolarEdge or other solar?

Yes. 

You can use Powerwall 3 as an AC coupled battery system with almost any other solar inverter.

Basically, any hybrid solar power system will work the same way as a dedicated AC coupled battery 
(such as the superseded Powerwall 2 or FranklinWH)

If there's a legacy solar inverter on site, the hybrid system will harvest energy from it.

We have more articles on the features, when Powerwall 3 makes sense, and how it works with 3 phase.

However, there are some important details to be aware of below.





Firstly there's technical compliance:

1. If you have a legacy solar power system, adding a new inverter will require a new connection agreement with your local Distribution Network Service Provider. (DNSP)
    
2. 17 different DNSPs across the country have different requirements, but they generally rely on the CEC-approved inverter list when determining what's eligible for a new connection.
    
3. If your old inverter doesn't appear on the current list, can't be updated with current software, or can't be export limited to zero or 1.5kW... sadly it may not be granted permission to stay connected with your new equipment.

 
Secondly there's sizing:

1. Your new battery inverter generally needs to be equal or larger size than the solar inverter, unless there's a technical solution that allows the old inverter to be throttled during an outage.
    
2. Your DNSP rules may vary, but generally they allow 10kW of inverter generation to be connected to each phase of your incoming mains supply. 
   - Some allow an additional 10kW of battery inverter per phase
   - Some allow more inverter capacity by negotiation
   - Some count a hybrid as both generation and battery. ie 10kW hybrid maximum
   
   - For example, 10kW of Enphase solar could be coupled to a 10kW Powerwall 3, 
   - but the Powerwall cannot have any DC coupled solar connected.
   
   - Alternately you may be able to have 5kW of Enphase solar generation.
   - And the Powerwall 3 can be commissioned as a 5kW nominal capacity
    
3. There is often an overall 30kVa site limit, so 3 phase systems, battery, hybrid or combined can't be more than 30kW unless a $5000(?) fee is paid for a study and medium embedded generator approval.
    
4. If you have a 3 phase site, it needs to be balanced with 5kW across phases
   -Adding a 10kW Powerwall 3 with DC coupled solar may mean you need two more solar inverters to provide generation of at least 5kW on the other two phases and an integration to switch them all off if one fails.
    

Thirdly, there's the ability to black start

For Tesla Powerwall 2, there’s a feature called “Wait for Solar.” When the battery reaches its reserve limit, a small amount of hidden energy is kept aside to allow the system to grid form for 6 minutes every hour between 8 AM and 4 PM. This gives the solar system a chance to start up and begin charging the battery.

• If you have legacy solar on-site, there must be a measuring coil hardwired into the PW3
• Nurio wireless meters aren't supported
   

We’ve also come to learn that PW3 isn’t compatible with Tigo optimisers, so they’re off the cards.


Tesla is promising that Powerwall 3 will be retro-compatible with Powerwall 2. 

• During August 2025 this was promised as "coming soon" but there's no firm release date so we're not holding our breath.