Note 15 - Business Segments - Operating Results for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 21,117	$ 14,012	$ 42,329	$ 27,782
Operating profit (loss)	(3,206)	(4,119)	(6,423)	(10,355)
Corporate, Non-Segment [Member]
Operating profit (loss)	(849)	(397)	(1,758)	(646)
Grid [Member]
Revenues	16,347	11,489	34,062	21,345
Grid [Member] | Operating Segments [Member]
Operating profit (loss)	(1,374)	(1,324)	(2,562)	(5,988)
Wind [Member]
Revenues	4,770	2,523	8,267	6,437
Wind [Member] | Operating Segments [Member]
Operating profit (loss)	$ (983)	$ (2,398)	$ (2,103)	$ (3,721)