Best Way to Expand My Home Solar Array

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I want to expand my current solar array to increase power output for an electric car and to cover all of my monthly electric bills/usage. Currently I have a 10-year old SunPower system in a string inverter configuration with 12 panels:

Inverter: SunPower SPR-3600p-TL-1 3.6 kW
Panels: SunPower E20/327 327 W
DC power comes down from the roof and is converted to AC at a large inverter mounted on the wall of my house.

There are two options I am considering to upgrade. Both will use 12 400W panels for a 4.8 kW add-on.

1. Add a separate, independent Enphase system with a microinverter on each panel.
Pros: a. Low cost ($3,000 cheaper than option 2 after 30% federal tax credit). b. Does not disturb existing system so the 25 year original panel warranty remains intact. c. Microinverters eliminate the single point of failure of a central inverter and carry a longer (25 year) warranty.
Cons: a. Two completely separate systems, one DC and one AC (power coming down off the roof), with two monitoring apps. b. Only the new panels (half the system) will be able to connect to/charge a home storage battery. c. To charge a car or battery, power will go through two conversions from DC to AC to DC, wasting energy. d. Enphase IQ8 microinverters can power essential devices in my home during a daytime outage without a battery. e. My original inverter will die in a few years requiring an expensive replacement. This approach does nothing to reduce/eliminate that cost which reduces the savings vs option 2.

2. Add a SolarEdge system with power optimizers at each panel. Upgrade the old panels with power optimizers also and connect all 24 panels to a SolarEdge 7.6 kW inverter.
Pros: a. A single large array with all 24 panels and a single monitoring app. b. All 24 panels can charge a home storage battery (faster charging). c. All 24 panels can directly charge a car without any energy-wasting conversion. The energy goes directly from the panels to the car without passing through the inverter. d. Original panels will perform better with the added optimizers increasing their power output. e. My current inverter life expectancy is only another few years. This will replace it with a new SolarEdge inverter eliminating an expensive repair later.
Cons: a. $3,000 more expensive after 30% federal tax credit. b. 25 year warranty on original panels is voided. c. Inverter is a single point of failure and carries a 10 or 15 year warranty vs. 25 years on microinverters. d. No power available during a daytime outage unless a battery is added.

Which do you think is the better approach and why?

Thank you!

The Solar Hub Team
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