The sun is important, and yet frequently overlooked by modern day pagans. The sun sustains life on this planet, and is important source of energy. It's a symbol of the god. Its energy is active in a positive way. It radiates the same energy the moon reflects. The dates of the 8 sabbats correspond to the position of the sun, and the more generic modern day horoscopes are based on the sun's position on the date of one's birth.
It's been my experience that solar correspondences are often
ignored in favor of lunar correspondences. Considering that solar energy is regarded as masculine, and generally associated with the god, this is not really surprising as the god is often ignored in favor of the goddess by many pagans. But
it can be useful, especially if you need to do
a positive(increasing) working during the waning moon.

If you need to do a positive working during the waning moon,
it can be done during the daylight hours with noon being the peak,
or height of power. By noon I do not mean 12:00 PM, I mean the exact
middle of the daylight hours, halfway between dawn and dusk. Use an
almanac to determine the exact times.
This can also be used anytime you need to do a daytime
working, not just in the waning moon.
This would also be appropriate if you are doing a working based on solar energy or if you are are doing a ritual to honor a sun deity.

Solar energy is at its strongest at the Summer solstice, about June 22 north of the equator and December 22 south of the equator

Solar energy is at its softest at the Winter Solstice, on or around December 22nd if you are North of the equator, on or around June 22nd if
you are South of the equator. Bear in mind Solar energy can be used at
any time of the year, these are just the stronger and weaker points.