Alone products increased by $9,839 per unit, or 46%, from $21,383 per unit during the six months ended December 31, 2020, to $31,222 per unit during the six months ended December 31, 2021. This was due to the introduction of higher-powered Stand Alone chargers in late 2020, which command a higher price.
A Distributed Charger site is based on a two-user unit configuration. Sales of Distributed Chargers decreased by 52 sites, or 28%, from 186 sites for the six months ended December 31, 2020 to 134 sites for the six months ended December 31, 2021. This was due to the fulfillment of a major Distributed Charger contract primarily in 2020 with a finalization in early 2021. The average selling price of Distributed Chargers decreased by $4,446 per site, or 3%, from $136,774 per site during the six months ended December 31, 2020, to $132,328 per site during the six months ended December 31, 2021.
During the six months ended December 31, 2021, a number of customers, including two of our most significant customers, requested us to provide our products on a bill-and-hold basis. Changes and delays to the customers’ site rollout schedules has contributed to the significant bill-and-hold arrangements for this period. The revenue under the bill-and-hold arrangements for the six months ended December 31, 2021 contributed to 47% of our total revenue.
Service and Maintenance Revenue
Service and maintenance revenue increased by $0.5 million, or 25%, from $1.9 million during the six months ended December 31, 2020, to $2.4 million during the six months ended December 31, 2021, primarily derived from new service-level agreements (“SLAs”).
Cost of Goods Sold
Cost of goods sold increased by $19.6 million, or 58%, from $33.9 million during the six months ended December 31, 2020, to $53.5 million during the six months ended December 31, 2021, primarily attributable to an increase in production of chargers.
Hardware—Cost of Goods Sold
Hardware—cost of goods sold increased by $18.8 million, or 57%, from $32.7 million during the six months ended December 31, 2020, to $51.5 million during the six months ended December 31, 2021, primarily attributable to an increase in volume and the average cost of Stand Alone products and Distributed Chargers.
The average cost of Stand Alone products increased by $9,555 per unit, or 49 %, from $19,558 per unit during the six months ended December 31, 2020, to $29,113 per unit during the six months ended December 31, 2021. This increase was due to the introduction of our high-powered range of new chargers, which have higher manufacturing costs.
The average cost of Distributed Chargers decreased by $5,384 per site, or 8%, from $139,581 per site during the six months ended December 31, 2020, to $128,813 per site during the six months ended December 31, 2021. This was due to an increased proportion of lower-powered charger sales, which have lower manufacturing costs within the Distributed Charger range.
Service and Maintenance—Cost of Goods Sold
Service and maintenance—cost of goods sold increased by $0.8 million, or 69%, from $1.2 million during the six months ended December 31, 2020, to $2.0 million during the six months ended December 31, 2021. The increase was primarily attributable to a reduction in non-recurring contract services, which have relatively lower service-related cost of goods sold, and an increase in SLAs entered into, which have higher service-related cost of goods sold.
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