For comparison,
Location: NE Scotland
System = 4kW (16 x 270W panels)
June 2021 (Summer) = 601.219kWh generated
My old 3kW system (12 x 250W) produced 428kWh in November last year, so a 5.1kW system in the exact same location should produce 727kWh. Round it to 700kWh. That's not as good as yours scaled, but I'm paying a penalty with my non-ideal roof orientation, angle, and shading from the house next door (which is up a slope)