Accounting policies - Disaggregated revenue (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Total Revenue	$ 33,390,557	$ 49,854,075	$ 105,559,105	$ 126,960,328
Contracts in progress.
Net Income (Loss)	4,454,464	8,605,129	26,779,069	19,742,526
Income (loss) from operations	$ 4,880,271	$ 10,741,938	$ 17,205,055	$ 24,749,908
Increase in basic earnings	$ 0.31	$ 0.56	$ 1.02	$ 1.30
Increase in diluted earnings	$ 0.31	$ 0.55	$ 1.01	$ 1.28
Retail revenue [Member]
Total Revenue	$ 7,585,992	$ 7,216,574	$ 24,392,814	$ 22,560,998
Bulk revenue [Member]
Total Revenue	8,767,168	8,488,615	25,557,220	25,975,483
Services revenue [Member]
Total Revenue	12,677,837	29,427,664	42,017,917	66,243,328
Services revenue [Member] | Transferred over Time [Member]
Total Revenue	4,246,506	24,219,737	17,631,774	52,648,271
Services revenue [Member] | Transferred at Point in Time [Member]
Total Revenue	8,431,331	5,207,927	24,386,143	13,595,057
Manufacturing revenue [Member]
Total Revenue	4,359,560	4,721,222	13,591,154	12,180,519
Construction Sevices [Member]
Total Revenue	3,637,038	24,204,446	16,165,312	52,563,822
Operations and Maintenance [Member]
Total Revenue	7,492,121	5,021,081	21,660,396	12,750,902
Design and Consulting Services [Member]
Total Revenue	$ 1,548,678	$ 202,137	$ 4,192,209	$ 928,604