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Note 2 - Revenue Recognition - Revenues By Major Customers (Details) - Customer Concentration Risk [Member] - Revenue Benchmark [Member] | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018
Wind [Member] | Inox Wind Limited [Member] |  |  |  |
Concentration risk percentage |  | 45.00% | 17.00% | 36.00%
Grid [Member] | Micron Technology [Member] |  |  |  |
Concentration risk percentage |  |  | 14.00% |
Grid [Member] | Vestas WTG Mexico [Member] |  |  |  |
Concentration risk percentage |  | 11.00% |  | 23.00%
Grid [Member] | Quanta Power [Member] |  |  |  |
Concentration risk percentage | 0.00% | 12.00% | 0.00% |
Grid [Member] | Hoffman Construction [Member] |  |  |  |
Concentration risk percentage | 25.00% | 0.00% | 12.00% | 0.00%
Grid [Member] | M.J. Electric, LLC [Member] |  |  |  |
Concentration risk percentage | 25.00% | 0.00% | 13.00% | 0.00%

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13531-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592 + Details
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- Details
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