What is the name or your project? I’m interested in being a customer. When do you hope to have the first product released?

You want a “hybrid” or “off-grid” inverter (as opposed to a grid-tie inverter). Check out Signature Solar and peruse their products. Stick with UL rated hardware, for example the EG4 12kPV Hybrid Inverter

Batteries are commonly put in parallel to create a battery bank big enough for your needs.