Bjorn Graabek kindly sent me the this chart of the effect of the eclipse on the output from his PV system near Wokingham. He indicates that it was cloudy this morning.

Bjorn Graabek 6 kW PV on 20th March, the day of the eclipse.

In North Wales it was very clear but I didn't have the wit to record the output from our PV system minute by minute. However the 2.5 kW installation (SE facing) was producing about 1.2 kW at 8.45 and this fell to just over 100 watts at 9.30, a fall of over 90%. It then rapidly rose to about 1.4 kW at 10.15.