I was planning on slowly raising my CYA from 30 ppm to 80 ppm but to take advantage of solar, I am running my pump during the day.

One thought though is that pools with solar covers should have a considerable sheilding effect of UV. Experiencing an increase in production with a solar cover may indicate the same thing as doing the test overnight.

Another way to perform a shorter test would be to put the SWG into spa mode and run for a measured period of time. This would make it easier to test the chlorine levels since they should be higher and the test could be done in a much shorter period of time.