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Note 9 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2019
Deferred Tax Assets, Tax Credit Carryforwards	$ 1,277,006	$ 1,437,670
Deferred Income Tax Liabilities, Net	2,277,550	1,890,562
Deferred Income Tax Assets, Net	617,390	771,746
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	273,936
Domestic Tax Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Effective Income Tax Rate Reconciliation, Tax Credit, Amortization, Period (Year)				20 years
Tax Credit Carryforward, Annual Amortization Amount	0	0
Research Tax Credits, Settlement, Percentage					40.00%
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 705,848
Open Tax Year	2018 2019
Domestic Tax Jurisdiction [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]
Deferred Tax Liabilities, Regulatory Assets and Liabilities	$ 2,568,143
Domestic Tax Jurisdiction [Member] | Internal Revenue Service (IRS) [Member] | Federal Energy Investment Tax Credit [Member]
Effective Income Tax Rate Reconciliation, Tax Credit, Amortization, Period (Year)			20 years
Tax Credit Carryforward, Annual Amortization Amount	$ 127,404	$ 127,404
Tax Credit Carryforward, Amount			$ 1,892,164
Deferred Tax Assets, Tax Credit Carryforwards			$ 655,862
State and Local Jurisdiction [Member] | Virginia, Jurisdiction [Member]
Open Tax Year	2022 2023 2024 2025

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