4.  Customer Concentrations and Accounts Receivable

E-Finity Distributed Generation, LLC (“E-Finity”) and RSP Systems, two of the Company’s domestic distributors, and Radian Oil & Gas Services Co, one of the Company’s international direct customers, accounted for 13%, 10%, and 10% of revenue for the three months ended December 31, 2021, respectively. Cal Microturbine, one of the Company’s domestic distributors, and Supernova Energy Services, one of the Company’s Latin American distributors, accounted for 24% and 12% of revenue for the three months ended December 31, 2020, respectively. E-Finity accounted for 15% of revenue for the nine months ended December 31, 2021. Cal Microturbine accounted for 16% of revenue for the nine months ended December 31, 2020.

Additionally, E-Finity accounted for 20% and 13% of net accounts receivable as of December 31, 2021 and March 31, 2021, respectively. The Company recorded a net bad debt recovery of approximately $0.2 million during the three and nine months ended December 31, 2020. The Company had no bad debt expense during the three and nine months ended December 31, 2021.