Electricity needs when the grids down.

[Skean Dhude]

Most solar panel on houses link into the system in such a way that they can only put their electrickery onto the national grid. What that means if the mains goes down then your house goes with it.

You can easily convert that but you need additional hardware and the capability of rerouting the system. This is not recommended by the electrickery boards as it creates a H&S risk if they are working on a system that is being supplied power.

IMO best get the kit and after an event you can modify it to get your output. Disadvantages are obviously that if you miss a part or break something while converting then it won't work. You may also discover then that your sized supply doesn't provide the power you planned on.