A calendar based on the motion of the sun around the celestial sphere.  A successful solar calendar is always synchronized with the seasons.  The calendar we use today is solar – January is always winter and July is always summer, etc.

a calendar based on solar cycles

a calendar consisting of years which accord with seasonal (or tropical) years

a calendar whose date indicates the season for a given place on Earth

a calendar whose dates indicate the season and so are synchronized to the declination

Any calendar system based on the orbit of the Earth around the Sun. Our current Gregorian Calendar is a solar calendar.

A calendar that was designed to keep in sync with the sun, but not the moon's phases.

A solar calendar is a calendar whose dates indicate the position of the earth on its revolution around the sun (or equivalently the apparent position of the sun moving on the celestial sphere).