Note 7 - Short-term and Long-term Warranty Reserves (Details) - USD ($)	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014
Short-term warranty reserve	$ 289,660	$ 261,328		$ 289,660
Long-term warranty reserve	25,958	52,951		25,958
Total warranty reserve	$ 315,618	$ 314,279	$ 317,822	$ 315,618	$ 300,771	$ 327,236	$ 314,311