“So why did Rabbi Schneerson get it twenty eight years ago, when so many other smart people didn’t? The date of his utterance, April 11th, 1981 provides us with a clue. The Lubavitcher Rebbe gave his speech on solar power three days after the last Birkhat Hahama celebration…
Speaking on the Shabbat after the last Birkhat Hahama, Rabbi Schneerson was doing just that. He was challenging his listeners to use that day, an obscure but precious resource from our tradition, to think about whether their generation was using the sun’s blessings wisely.”
Read it all here.
Here’s the a clip from the sicha he references: (You will note that this Farbrengen, held in honor of the Rebbe’s birthday, did not take place on Shabbos. Chabad.org tells me that 11 Nissan 1981 was a Wednsday.)