Honestly if the inverter and batteries are basically free, adding panels is a no-brainer. The installation cost you're worrying about now could pay itself back within 2-3 years just from Eskom savings, and after that your electricity bill pretty much disappears. We went that route with HomeLink Solar and it changed the whole calculation completely. On the 13000VA passthrough question — worth confirming directly with Sungrow because if it genuinely handles that load, putting the whole house on it removes the DB split headache entirely. That said, with only 6kW inverter output and 9.6kWh battery, I'd be cautious. During loadshedding you'd need to be very mindful of what's running simultaneously — geysers, stoves, aircons all competing on 6kW gets uncomfortable fast.