What would be the best option for back up power at car garage, currently i have a 3kva generator but i want to replace it, i want solar inverter, would it be a good option?
You would have to do the math to determine if solar and an inverter is economically feasable. There are several web sites and even free calculator apps to help you make your decision. Just Google them.
As js said. You have to figure out your usage and demands. Do you need only 110V or do you have 220V? How much equipment do you have that draws how much power for how long? What is the start up needs vs the running needs?