Yes, you can convert a grid-tied solar system to include battery storage. Pay attention to AC and DC operating voltages, system design, and installation needs. Your existing system remains unchanged, except that when your utility goes down your grid tied inverter runs power through an added battery-based inverter connected to energy storage (batteries). 6kw system with two strings into a Sungrow SG5K-D 5kw Inverter and a second 3. I am not ready to go off grid at this stage and wish to draw from the grid when required.