The decrease is primarily due to decreases in operating costs discussed earlier. Turning to our full year results, for the full year 2023, we generated total revenues of $8.3 million, compared to $5.4 million in 2022, representing a 55.1% increase. Full year product and service revenues increased to $8 million from $4.9 million in the prior year, representing a 2.9% increase, while grant revenues decreased to $0.33 million from $0.5 million representing a 28.9% decrease. Margins on product and service revenues was 12.8% for the full year compared to 14.6% last year. The lower margins for the full year was negatively impacted mostly by a higher mix of hardware charging station sales in addition to the impact of lower margin school bus sales in the third quarter, offset by a lower mix of engineering services.
Operating expenses excluding cost of sales was $33.5 million for full year 2023 compared to $38.1 million for the full year 2022. The decrease was primarily attributable to lower payroll benefits and stock-based compensation, in addition to reduced travel, marketing and professional fees. Losses from operations for the full year improved by $4.8 million from a loss of $32.1 million this year compared to $36.9 million last year. Other income was $0.8 million for the full year, compared to $12.4 million in the prior year. The year-over-year decrease in other kit income was primarily driven by the change in the fair value of warrants liability and derivative liability, partially offset by gains realized from the sale of our equity investment in Switch EV Limited.
Net loss attributable to common stockholders for the full year increased by $7.3 million to $32.2 million, compared with $24.9 million for the full year 2022. We had approximately $1.5 million in cash as of December 31, 2023, excluding $0.5 million in restricted cash. As Gregory mentioned, in the first quarter of 2024, we raised $9.6 million in new capital to provide us with additional liquidity and flexibility as we continue our efforts to scale the business. Total cash decreased by $12.3 million in the fourth quarter, primarily attributed to the return of customers related to EPA awards of $9.8 million and cash operating losses of $6.9 million offset by positive working capital. Inventory decreased by $0.9 million to $5.9 million at the end of the fourth quarter from $6.8 million at the end of the third quarter 2023.
Accounts payable at the end of the fourth quarter was flat compared to the end of the third quarter at $1.7 million. As Gregory shared, megawatts under management increased by 18% in the fourth quarter. For the full year, megawatts under management increased by 44.6%. Megawatts under management comprised of 7.1 megawatts for stationary batteries and 18 megawatts from EV chargers. We continue to expect an acceleration in our megawatts under management in 2024 as we commission our backlog of customer orders we earned in 2023. In addition of new business we anticipate winning, which we have visibility to in our pipeline for both EV chargers and stationary batteries. Now turning to backlog, at December 31st, our hardware and services backlog was $3.9 million and as of January 2024, our backlog increased to $20 million.
Looking out to 2024, we are confident that the momentum we saw this quarter will continue into 2024, driving accelerated deployments, increasing grid service revenues and expanded top-line growth. And with that, Gregory, back to you to wrap up our prepared remarks.
Gregory Poilasne: Thanks, David. In summary, we are pleased with our results and the momentum we are seeing across our business as we are entering 2024. The key progress we are making across the business is reflective of our commitment to environmental sustainability, demonstrate the promises of our technology and is laying the ground for continued expansion and value creation in 2024 and beyond. Thank you all for attending this call and, more importantly, trusting our vision. With that, I will turn the call to the operator and will open the line for any questions. Operator?
Operator:
Operator: There are no questions at this point of time. This concludes today’s teleconference. You may disconnect your lines at this time. Thank you for your participation.
