I have compared the 6.4 dm² panels with my 11.2 dm² a sunny winter day with a clear blue sky. The light intensity peaked at 55000 lux.

The theoretically available power P at 55000 lux and a 11.2 dm² panel with 0.16% efficiency is:

P = 55000*0.000079*11.2*0.16 = 7.8 Watt ( I measured close to 6.6 Watt on the battery side )

Plotly 5 jan, comparison 6.4 dm² vs 11.2 dm²

Plotly 4 jan,clear blue sky 11.2 dm² panel