5.  Customer Concentrations and Accounts Receivable

Accounts receivables are presented on the Condensed Consolidated Balance Sheets, net of estimated credit losses. The carrying amounts of trade accounts receivable represent the maximum credit risk exposure of these assets. On a quarterly basis, in accordance with ASC 326, the Company evaluates the collectability of outstanding accounts receivable balances to determine an allowance for credit loss that reflects its best estimate of the lifetime expected credit losses. The Company evaluated its current estimate of expected credit losses and determined that there was no significant change. It took into account certain economic factors in calculating the risk factors used to determine the CECL historical loss rate for each aging bucket.  Additionally, the Company analyzed the risk of its receivables using geography and other customer circumstances to determine its allowance for credit risk. Changes in the CECL allowance for accounts receivable are as follows (in thousands):

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Cal Microturbine, one of the Company’s domestic distributors, accounted for 17% of revenue for the three months ended December 31, 2023. RSP Systems and Cal Microturbine, two of the Company’s domestic distributors, accounted for 21% and 14% of revenue for the three months ended December 31, 2022, respectively. E-Finity Distributed Generation (“E-Finity”) and Cal Microturbine accounted for 14% and 11% of revenue for the nine months ended December 31, 2023, respectively. Cal Microturbine and RSP Systems accounted for 16% and 13% of revenue for the nine months ended December 31, 2022, respectively.

Additionally, IBT Energies and Supernova Energy Services accounted for 15% and 14% of net accounts receivable as of December 31, 2023. E-Finity accounted for 12% of net accounts receivable as of March 31, 2023. The Company recorded a credit loss expense of zero during the three and nine months ended December 31, 2023, respectively. The Company recorded a credit loss expense of $0.3 million and $0.4 million during the three and nine months ended December 31, 2022, respectively.