בהעלתך את הנרות - נר נשמה

בהעלתך את הנרות - נר נשמה

There is no mention anywhere in Shas or Shulchan Aruch to light a candle on the day of a Yahrzeit.

The Chasam Sofer (Shu"t #6:27) writes he is unaware of a so-called מצוה רבה to light Yahrzeit candles at home or even at the Kever.

The ביאור הלכה ס' תקיד  quotes from the  שו"ת כתב סופר (O.Ch65) that "on YomTov when we may not light

a נר של בטלה ( a candle that has no purpose) it is best to light the Yahrzeit candle (if it wasn't lit before Yom Tov) in the room where you eat (purpose) or even better, to light it in Shul.(Mitzvah)

Only for a שעת הדחק may we light a Yahrzeit candle for parents* since it's done for their honor (כיבוד אב ואם)

According to the Maharshal even for parents might not be a Mitzvah, but since everybody lights candles and some are

מקפיד on this more than other Mitzvos, therefore, we allow him to light the candle on Yom Tov, so he

will not be מצטער and have no Simchas Yom Tov." 

*  Seems, that lighting a candle for a Rebbe etc. (no Mitzvahs כיבוד אב ואם) may not be done on Yom Tov.