Ladybug - Solar Radiation Analysis

Hello guys!
I’ve been working on Ladybug - Solar Radiation Analysis, and I noticed a variation an obtained results by changing grid-size.
For example with the same facade:
-Grid size 1.00m (919095kWh/year)
-Grid size 0.50m (3676379kWh/year)
-Grid size 0.25m (14761220kWh/year)
Anyone could help me figure out and how does it work?

please upload your file…

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