Tesla Powerwall 2 (TP2)
If you have a Tesla Powerwall 2 battery and were hoping to expand it with another...
...it's too late. Production of PW2 has finished.
Tesla say that the new PW3 is incompatible with PW2.
Tesla Powerwall 3 (TP3). (Click blue link for datasheet)
Hybrid solar and battery inverter with a 13.5kWh battery.
Chemistry of the cells inside the battery is reportedly LFP (Lithium Iron Phosphate)
Solar inverter options for Australia are:
5kW, 10kW and 11.04kW, all single phase.
In Western Australia this means only the 5kW model will be allowed by Western Power.
The 5kW model will be allowed on both single and three phase homes in WA.
The 10kW and 11.04kW models will not be allowed in WA on either single or three phase.
Furthermore the WA rules will allow a second and third PW3 on the other two phases of a three phase home.
However this is not true '3 phase' so cannot backup three phase appliances during grid outages.
Each inverter has 3 x MPPTs which a MPPT voltage range of 60-480V
The maximum DC input voltage per MPPT is 550V
The input current is 26A
550V per MPPT means no more than 12 x typical 440W panels on a string.
You might squeeze 13 panels but run the risk of the inverter not starting due to over voltage on cold mornings.
(Panel voltage increases as temperature decreases)
Rather than trying to overload the MPPT with a long string, it might be better to parallel two shorter strings together.
That keeps the voltage of each string down and the PW3 can handle it with only a minor amount of 'clipping'.
You could, for instance have 2 x 7 panel strings in parallel instead of 14 on a single string.
The MPPT voltage range is only up to 480V which is another reason why shorter strings in parallel will do better than a long string.
PW3 uses the same 'Gateway 2' box as PW2.
Powerwall 3 and Tigo optimisers
According to Solarquotes, Tigo optimisers can't be used on Powerwall 3.
Tony from Solarquotes says...
"TIGOS are not compatible with Tesla PW3, I have that direct from Tesla's head of engineering in Australia"
Personally, I'm not convinced by this.
In the USA, yes, as their AFCI (arc fault detection) function might get a false positive, but that feature isn't available for PW3 in Australia.
It might be because Australian Powerwall 3 is designed to use parallel strings on each MPPT.
It has been the case forever, with any inverter, that optimisers selectively deployed on parallel strings cause problems.
You can put optimisers on ALL the panels on both parallel strings, but not sprinkle them where needed.
Is Tesla simply making their tech support life easier by saying 'no can do'?
I bet they work just fine if on a single string that isn't in parallel...but what if another string is added later?
Can Tesla Powerwall 3 be an AC Coupled battery like PW2 was?
If you have single phase, already have solar, and live in WA, then no.
The rules in WA are that you can have up to 5kW of solar inverter plus 5kW of battery inverter.
PW2 was a pure battery inverter and fine for this rule, but PW3 is a solar inverter.
So if you have a solar inverter already and want to add a PW3 with its 5kW solar inverter, you exceed your limit.
It won't matter whether you connect panels to the PW3 or not. It won't be approved.
The solution is to replace your existing solar inverter with the PW3, which is probably not what most people want to do.
PW2 is effectively gone now, can I expand it with a PW3?
No, PW3 and PW2 are incompatible with each other.
If you have a PW2 and want to expand your storage capacity beyond 13.5kWh, you are out of luck unless you can get one of the last PW2s.
Will PW3 be a success?
It already is, but I don't think it will do as well in WA compared to the East Coast.
Our 5kW single phase inverter maximum will make it less appealing, especially for those with three phase.
Price
$13,600 inc Gateway 2 + installation (typically $1,600 to $2,000) so about $16.5k depending on installation conditions.
That's competitive with Sungrow, iStore, Sigenergy, Goodwe single phase hybrid inverters and batteries.
Monolithic
Where its competitors can finesse a smaller or larger system in 3-5kWh modules, Tesla is all in at 13.5kWh.
If you want more then you have to add another 13.5kWh. There's no middle ground.