Warranty (Details) - USD ($)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Warranty cost and accrual information
Warranty accrual, beginning of period	$ 1,013,461	$ 1,009,368
Accrued expense for fiscal year	(5,926)	219,390
Warranty cost incurred for fiscal year	(152,583)	(215,297)
Warranty accrual, end of period	$ 854,952	$ 1,013,461