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 our receivables using geography and other customer circumstances to determine our allowance for credit risk. Changes in the CECL allowance for accounts receivable are as follows (in thousands):

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E-Finity Distributed Generation (“E-Finity”) and Cal Microturbine, two of the Company’s domestic distributors, accounted for 21% and 11% of revenue for the three months ended September 30, 2023, respectively. RSP Systems,

Capstone Engineered Solutions, Cal Microturbine, and Horizon Power Systems, four of the Company’s domestic distributors, accounted for 15%, 13%, 12%, and 10% of revenue for the three months ended September 30, 2022, respectively. E-Finity and Cal Microturbine accounted for 16% and 10% of revenue for the six months ended September 30, 2023, respectively. Cal Microturbine accounted for 18% of revenue for the six months ended September 30, 2022.

Additionally, E-Finity, IBT Energies and Supernova Energy Services accounted for 20%, 10% and 10% of net accounts receivable as of September 30, 2023, respectively. E-Finity accounted for 12% of net accounts receivable as of March 31, 2023. The Company recorded a credit loss expense of $0.1 million during the six months ended September 30, 2022.