SPD placement in consumer unit?

I'm fitting a manual change over switch in my consumer unit, so if anything went wrong with my vicyron inverter, I can flip the switch upwards to change over from inverter power to grid power. I have a SPD which I'm wondering which side of the change over switch should it be wired to, The grid side or the load side? I currently have it connected to the grid side, as my thinking is that any surges would come from the grid before going to my equipment and I wouldn't think the multiplus ii could give a surge if runningoff grid? (I do have SPD's on my solar arrays) So which side should the SPD go , grid side or load side?

I'm fitting a manual change over switch in my consumer unit, so if anything went wrong with my vicyron inverter, I can flip the switch upwards to change over from inverter power to grid power. I have a SPD which I'm wondering which side of the change over switch should it be wired to, The grid side or the load side? I currently have it connected to the grid side, as my thinking is that any surges would come from the grid before going to my equipment and I wouldn't think the multiplus ii could give a surge if runningoff grid? (I do have SPD's on my solar arrays) So which side should the SPD go , grid side or load side?