Based on the PowerWall+ specs, the inverter should be 7.6KW.
Should be reasonably safe to go up to about 9-9.5KW of panels depending on the exact panel specs, as long as it stays in the supported DC voltage ranges.
The most relevant specs are:
PV Maximum Input Voltage | 600 VDC |
PV Operating DC Input Voltage Range | 60 – 550 VDC |
PV DC MPPT Voltage Range | 60 – 480 VDC |
MPPTs | 4 (1-2-1-2 input connectors per MPPT) |
Maximum Current per MPPT | 13 A |
Maximum Short Circuit Current per MPPT | 15 A |
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I agree that the DIY method may be the only effective method, but it could cause warranty issues with Tesla, and you really need to make sure it is properly permitted, interconnect agreement, etc.
When we expanded our system, we expected we may have to change to the new compensation rate vs the old, We originally installed at a sell back rate of $0.86/kwh, and when we added panels the rate had changed to $0.076/kwh. Supposedly if you changed the system by up to 10% you did not need to move to the new rate. Our Installer stated that this would only apply if we changed our inverters, and since we were already installed and approved at the two 10KW inverters, we would not change rates.
-Harry