Hi, I read from the instructions I can achieve a "normal" day cycle by using the values of "0.25, 0.3, 0.75, 0.8", but what should I use as the capacitor multiplier now that daytime is reduced from the vanilla settings?

Thanks

"capacitor multiplier" only really applies if you're keeping the vanilla ratio of daytime to nighttime, and should be the same as the daylength multiplier (4 by default).

In Vanilla Factorio, or Clockwork with the settings above, the optimal solar ratio is 21:25 (about 0.84). However, once you change the ratio of daytime to nightime, this optimal ratio also changes. You'll need to math it out and make new solar designs based on that.

https://forums.factorio.com/viewtopic.php?t=5594

This post can guide you through computing the optimal ratio based on accumulator capacity and how much power you can expect solar panels to produce in a day.