● dc solar hybrid power systems . these systems incorporate photovoltaic and other sources of renewable energy into our dc hybrid power system . our dc power systems are available in diesel , natural gas , lpg / natural gas and renewable formats , with diesel , natural gas and propane gas being the predominate formats . during the years ended december 31 , 2020 and 2019 , 96 % and 96 % , respectively , of our total net sales were within the telecommunications market . in 2020 , 81 % of our total net sales were derived primarily from three customers which are in the telecommunications industry and each accounted for 52 % , 15 % and 14 % of total net sales for 2020. in 2019 , we had 91 % of our total net sales derived from our three largest customers which are in the telecommunications industry and each accounted for 68 % , 17 % and 6 % of our total net sales for 2019. in march 2020 , the world health organization declared the outbreak of covid-19 a global pandemic , and , in the following weeks , many u.s. states and foreign countries issued lockdown orders negatively impacting the operations of our manufacturing facilities and customer demand for our products . since then , the covid-19 situation within the u.s. and foreign countries has rapidly escalated . we have implemented new procedures to support the health and safety of our employees and we are following all guidelines issued by the u.s. centers for disease control and prevention , as well as federal , state and regional public health authorities . our manufacturing facilities have remained opened with certain limitations and restrictions to comply covid-19 safety guidelines and provide a safe work environment for our employees . covid-19 , has had and is likely to continue to have , a material and substantial adverse impact on our results of operations including , among others , a decrease in our sales , delays in sourcing of raw materials from suppliers which , in turn , has raised liquidity concerns . in addition , our inventory write-off increased during 2020 due to current uncertainties regarding specific product shipments . our business is directly dependent upon , and correlates closely with , the marketing levels and ongoing business activities of our existing customers and suppliers . in the event of a continued widespread economic downturn caused by covid-19 , we will likely experience a further reduction in current projects , longer sales and collection cycles , deferral or delay of purchase commitments for our dc power systems , a reduction in our manufacturing functionality , higher than normal inventory levels , a reduction in the availability of qualified labor , and increased price competition , all of which could substantially adversely affect our net revenues and our ability to remain a going concern . during december 2020 , the food and drug administration authorized the release of vaccines to help control covid-19 . although there are many unknown factors of its success to control covid-19 and the timeline of making the vaccine available to a great majority of people around the world , we believe these are significant events aimed to control covid-19 that may lead to improvements to the global economy and to our business . 35 the extent of the impact of covid-19 on our operational and financial performance will depend on certain developments , including the duration and spread of the outbreak , the impact on our customers and our sales cycles , the impact on our customer , employee or industry events , and the effect on our vendors , all of which are uncertain and can not be predicted . at this point , we are uncertain of the full magnitude that the pandemic may have on our financial condition , liquidity and future results of operations . critical accounting policies the preparation of financial statements in conformity with accounting principles generally accepted in the united states of america ( “ gaap ” ) requires management to make certain estimates and assumptions that affect the reported amounts of assets , liabilities , revenues and expenses , and the disclosure of contingent assets and liabilities . on an ongoing basis , management reviews its estimates and if deemed appropriate , those estimates are adjusted . significant estimates include those related to assumptions used in determining reserves for uncollectible receivables , assumptions used in valuing inventories at net realizable value , impairment analysis of long term assets , estimates of useful lives of property and equipment , assumptions used in valuing stock-based compensation , the valuation allowance for deferred tax assets , accruals for product warranties , accruals for potential liabilities , and assumptions used in the determination of the company 's liquidity . actual results may differ from those estimates . we believe that the following critical accounting policies , among others , affect our more significant judgment and estimates used in the preparation of our financial statements : revenue recognition we recognize revenue in accordance with financial accounting standards board accounting standards codification 606 , revenue from contracts with customers ( “ asc 606 ” ) . asc 606 requires entities to recognize revenue through the application of a five-step model , which includes : identification of the contract ; identification of the performance obligations ; determination of the transaction price ; allocation of the transaction price to the performance obligations ; and recognition of revenue as the entity satisfies the performance obligations . substantially all of the company 's revenue is derived from product sales . story_separator_special_tag during 2021 , we expect research and development expenses to gradually increase as control over covid-19 improves and we continue investing into new products as part of our strategy to diversify our product lines . general and administrative expenses . our general and administrative expenses increased by $ 58 , to $ 4,062 during 2020 , as compared to $ 4,004 during 2019. the increase was primarily due to an increase of approximately $ 500 in legal , audit , and broker fees services related to an equity raise that took place in july 2020 and consulting services for additional disclosures required as a result of covid-19 . interest and finance costs . during 2020 , our interest expense was $ 60 , as compared to $ 103 during 2019 , an increase of $ 43. our interest expense during 2020 included approximately $ 12 in fees in connection with selling $ 2.6 million of receivables to citibank under our supplier agreement , $ 41 in interest paid for financing of production equipment , $ 4 in interest paid under our line of credit with pinnacle bank , and $ 3 in interest paid for financing of insurance policies . other income ( expense ) , net . during 2020 , our interest income was $ 14 , as compared to $ 40 during 2019 , a decrease of $ 26. our other income included a $ 10 economic injury disaster grant . income tax benefit . in 2020 , we recognized a benefit from income taxes of $ 2,139 attributable to refundable federal and state income taxes . during 2019 , we did not recognize any benefit from income taxes as carry back claims of income taxes were applied . net loss . as a result of the factors identified above , we generated a net loss of $ 10,871 for 2020 , as compared to net loss of $ 4,045 for 2019 , an increase loss of $ 6,826. a significant portion of the increase in net loss can be attributed to the results of a decrease our of dc back-up power systems to us telecommunications customers , and an increase in factory overhead absorption , and $ 3,400 increase inventory reserve reported in our cost of sales during 2020. liquidity and capital resources story_separator_special_tag new roman , times , serif ; font-size : 10pt `` > paycheck protection program loan on may 4 , 2020 , we entered into a loan with citibank , n.a . in an aggregate principal amount of $ 1,715 , or the ppp loan , pursuant to the paycheck protection program , or the ppp , under the cares act . the ppp loan is evidenced by a promissory note dated may 4 , 2020. the ppp loan matures two years from the disbursement date and bears interest at a rate of 1 % per annum , with the first nine months of interest deferred . principal and interest are payable monthly commencing nine months after the disbursement date and may be prepaid by us at any time prior to maturity with no prepayment penalties . under the terms of the cares act , recipients of ppp loans can apply for and be granted forgiveness for all or a portion of loans granted under the ppp . the ppp loan is subject to forgiveness to the extent proceeds are used for payroll costs , including payments required to continue group health care benefits , and certain rent , utility , and mortgage interest expenses ( collectively , “ qualifying expenses ” ) , pursuant to the terms and limitations of the ppp . we intend to use a significant majority of the ppp loan amount for qualifying expenses and expect the full amount of the ppp loan to be forgiven . however , no assurance can be given that we will obtain forgiveness of the ppp loan in whole or in part . 42 future capital requirements on february 7 , 2021 , we entered into an underwriting agreement with thinkequity , a division of fordham financial management , inc. , pursuant to which we agreed to sell an aggregate of 750,000 shares of our common stock in a firm commitment underwritten public offering at a price per share to the public of $ 18.00. the public offering closed on february 10 , 2021. we received net proceeds of approximately $ 12.5 million and we plan to use the net proceeds for general corporate purposes . we believe that the current funds on hand will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next twelve months . we continue to review operations in order to identify additional strategies designed to generate cash flow , improve our financial position , and enable the timely discharge of our obligations . cash flow the following table sets forth the significant sources and uses of cash for the periods set forth below : replace_table_token_2_th operating activities net cash used in operating activities for 2020 was $ 6,548 , as compared to $ 2,167 for the same period in 2019. this increase in net cash used in 2020 was primarily due to a net loss of $ 10,871 , a write-down of $ 3,400 for excess and obsolete inventory , an increase in income tax benefit of $ 2,139 , coupled with a decrease of $ 907 in prepaid assets resulting from engines imported from japan which had been prepaid in 2019. investing activities net cash used in investing activities for 2020 totaled $ 19 , as compared to $ 338 for 2019 , a decrease of $ 319. the net cash used in investing activities in 2020 was attributable to a slight increase in new manufacturing equipment . financing activities net cash provided by financing activities totaled $ 5,373 for 2020 , as compared to $ 295 used in financing activities during 2019 , an increase of $ 5,668.

sources of liquidity during the year ended december 31 , 2020 , we funded our operations primarily from cash on hand and sales of receivables under our supplier agreement with citibank . these funds were also used to increase inventory to support research and development projects and the launch of our new line of lpg / natural gas generators . as of december 31 , 2020 , we had working capital of $ 10,123 , as compared to working capital of $ 16,433 at december 31 , 2019. this $ 6,310 decrease in working capital is primarily attributable to a $ 1,194 decrease in cash and cash equivalents resulting from net cash of $ 6,548 used in operating activities , net cash used in investing activities of $ 19 from the acquisition of new property and equipment , and net cash from financing activities of $ 5,372 which included proceeds of $ 1,715 from a paycheck protection program ( “ ppp ” ) loan , proceeds of $ 2,812 from the issuance of common stock and warrants in our july 2020 private placement and proceeds of $ 1,174 from the exercise of certain of these warrants . on december 31 , 2020 and december 31 , 2019 , our net trade receivables totaled $ 1,190 and $ 934 , respectively . on december 31 , 2020 , $ 1,041 ( 87 % ) and $ 53 ( 5 % ) represented the two largest open customer account balances , while $ 652 ( 70 % ) and $ 183 ( 20 % ) represented the two largest open customer account balances on december 31 , 2019. our available capital resources on december 31 , 2020 consisted primarily of $ 1,646 in cash and cash equivalents , as compared to $ 2,840 as of december 31 , 2019. we expect our future capital resources will consist primarily of cash on hand , cash generated by operations , if any , and future debt or equity financings , if any .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```sources of liquidity during the year ended december 31 , 2020 , we funded our operations primarily from cash on hand and sales of receivables under our supplier agreement with citibank . these funds were also used to increase inventory to support research and development projects and the launch of our new line of lpg / natural gas generators . as of december 31 , 2020 , we had working capital of $ 10,123 , as compared to working capital of $ 16,433 at december 31 , 2019. this $ 6,310 decrease in working capital is primarily attributable to a $ 1,194 decrease in cash and cash equivalents resulting from net cash of $ 6,548 used in operating activities , net cash used in investing activities of $ 19 from the acquisition of new property and equipment , and net cash from financing activities of $ 5,372 which included proceeds of $ 1,715 from a paycheck protection program ( “ ppp ” ) loan , proceeds of $ 2,812 from the issuance of common stock and warrants in our july 2020 private placement and proceeds of $ 1,174 from the exercise of certain of these warrants . on december 31 , 2020 and december 31 , 2019 , our net trade receivables totaled $ 1,190 and $ 934 , respectively . on december 31 , 2020 , $ 1,041 ( 87 % ) and $ 53 ( 5 % ) represented the two largest open customer account balances , while $ 652 ( 70 % ) and $ 183 ( 20 % ) represented the two largest open customer account balances on december 31 , 2019. our available capital resources on december 31 , 2020 consisted primarily of $ 1,646 in cash and cash equivalents , as compared to $ 2,840 as of december 31 , 2019. we expect our future capital resources will consist primarily of cash on hand , cash generated by operations , if any , and future debt or equity financings , if any .
```    
 Suspicious Activity Report : ● dc solar hybrid power systems . these systems incorporate photovoltaic and other sources of renewable energy into our dc hybrid power system . our dc power systems are available in diesel , natural gas , lpg / natural gas and renewable formats , with diesel , natural gas and propane gas being the predominate formats . during the years ended december 31 , 2020 and 2019 , 96 % and 96 % , respectively , of our total net sales were within the telecommunications market . in 2020 , 81 % of our total net sales were derived primarily from three customers which are in the telecommunications industry and each accounted for 52 % , 15 % and 14 % of total net sales for 2020. in 2019 , we had 91 % of our total net sales derived from our three largest customers which are in the telecommunications industry and each accounted for 68 % , 17 % and 6 % of our total net sales for 2019. in march 2020 , the world health organization declared the outbreak of covid-19 a global pandemic , and , in the following weeks , many u.s. states and foreign countries issued lockdown orders negatively impacting the operations of our manufacturing facilities and customer demand for our products . since then , the covid-19 situation within the u.s. and foreign countries has rapidly escalated . we have implemented new procedures to support the health and safety of our employees and we are following all guidelines issued by the u.s. centers for disease control and prevention , as well as federal , state and regional public health authorities . our manufacturing facilities have remained opened with certain limitations and restrictions to comply covid-19 safety guidelines and provide a safe work environment for our employees . covid-19 , has had and is likely to continue to have , a material and substantial adverse impact on our results of operations including , among others , a decrease in our sales , delays in sourcing of raw materials from suppliers which , in turn , has raised liquidity concerns . in addition , our inventory write-off increased during 2020 due to current uncertainties regarding specific product shipments . our business is directly dependent upon , and correlates closely with , the marketing levels and ongoing business activities of our existing customers and suppliers . in the event of a continued widespread economic downturn caused by covid-19 , we will likely experience a further reduction in current projects , longer sales and collection cycles , deferral or delay of purchase commitments for our dc power systems , a reduction in our manufacturing functionality , higher than normal inventory levels , a reduction in the availability of qualified labor , and increased price competition , all of which could substantially adversely affect our net revenues and our ability to remain a going concern . during december 2020 , the food and drug administration authorized the release of vaccines to help control covid-19 . although there are many unknown factors of its success to control covid-19 and the timeline of making the vaccine available to a great majority of people around the world , we believe these are significant events aimed to control covid-19 that may lead to improvements to the global economy and to our business . 35 the extent of the impact of covid-19 on our operational and financial performance will depend on certain developments , including the duration and spread of the outbreak , the impact on our customers and our sales cycles , the impact on our customer , employee or industry events , and the effect on our vendors , all of which are uncertain and can not be predicted . at this point , we are uncertain of the full magnitude that the pandemic may have on our financial condition , liquidity and future results of operations . critical accounting policies the preparation of financial statements in conformity with accounting principles generally accepted in the united states of america ( “ gaap ” ) requires management to make certain estimates and assumptions that affect the reported amounts of assets , liabilities , revenues and expenses , and the disclosure of contingent assets and liabilities . on an ongoing basis , management reviews its estimates and if deemed appropriate , those estimates are adjusted . significant estimates include those related to assumptions used in determining reserves for uncollectible receivables , assumptions used in valuing inventories at net realizable value , impairment analysis of long term assets , estimates of useful lives of property and equipment , assumptions used in valuing stock-based compensation , the valuation allowance for deferred tax assets , accruals for product warranties , accruals for potential liabilities , and assumptions used in the determination of the company 's liquidity . actual results may differ from those estimates . we believe that the following critical accounting policies , among others , affect our more significant judgment and estimates used in the preparation of our financial statements : revenue recognition we recognize revenue in accordance with financial accounting standards board accounting standards codification 606 , revenue from contracts with customers ( “ asc 606 ” ) . asc 606 requires entities to recognize revenue through the application of a five-step model , which includes : identification of the contract ; identification of the performance obligations ; determination of the transaction price ; allocation of the transaction price to the performance obligations ; and recognition of revenue as the entity satisfies the performance obligations . substantially all of the company 's revenue is derived from product sales . story_separator_special_tag during 2021 , we expect research and development expenses to gradually increase as control over covid-19 improves and we continue investing into new products as part of our strategy to diversify our product lines . general and administrative expenses . our general and administrative expenses increased by $ 58 , to $ 4,062 during 2020 , as compared to $ 4,004 during 2019. the increase was primarily due to an increase of approximately $ 500 in legal , audit , and broker fees services related to an equity raise that took place in july 2020 and consulting services for additional disclosures required as a result of covid-19 . interest and finance costs . during 2020 , our interest expense was $ 60 , as compared to $ 103 during 2019 , an increase of $ 43. our interest expense during 2020 included approximately $ 12 in fees in connection with selling $ 2.6 million of receivables to citibank under our supplier agreement , $ 41 in interest paid for financing of production equipment , $ 4 in interest paid under our line of credit with pinnacle bank , and $ 3 in interest paid for financing of insurance policies . other income ( expense ) , net . during 2020 , our interest income was $ 14 , as compared to $ 40 during 2019 , a decrease of $ 26. our other income included a $ 10 economic injury disaster grant . income tax benefit . in 2020 , we recognized a benefit from income taxes of $ 2,139 attributable to refundable federal and state income taxes . during 2019 , we did not recognize any benefit from income taxes as carry back claims of income taxes were applied . net loss . as a result of the factors identified above , we generated a net loss of $ 10,871 for 2020 , as compared to net loss of $ 4,045 for 2019 , an increase loss of $ 6,826. a significant portion of the increase in net loss can be attributed to the results of a decrease our of dc back-up power systems to us telecommunications customers , and an increase in factory overhead absorption , and $ 3,400 increase inventory reserve reported in our cost of sales during 2020. liquidity and capital resources story_separator_special_tag new roman , times , serif ; font-size : 10pt `` > paycheck protection program loan on may 4 , 2020 , we entered into a loan with citibank , n.a . in an aggregate principal amount of $ 1,715 , or the ppp loan , pursuant to the paycheck protection program , or the ppp , under the cares act . the ppp loan is evidenced by a promissory note dated may 4 , 2020. the ppp loan matures two years from the disbursement date and bears interest at a rate of 1 % per annum , with the first nine months of interest deferred . principal and interest are payable monthly commencing nine months after the disbursement date and may be prepaid by us at any time prior to maturity with no prepayment penalties . under the terms of the cares act , recipients of ppp loans can apply for and be granted forgiveness for all or a portion of loans granted under the ppp . the ppp loan is subject to forgiveness to the extent proceeds are used for payroll costs , including payments required to continue group health care benefits , and certain rent , utility , and mortgage interest expenses ( collectively , “ qualifying expenses ” ) , pursuant to the terms and limitations of the ppp . we intend to use a significant majority of the ppp loan amount for qualifying expenses and expect the full amount of the ppp loan to be forgiven . however , no assurance can be given that we will obtain forgiveness of the ppp loan in whole or in part . 42 future capital requirements on february 7 , 2021 , we entered into an underwriting agreement with thinkequity , a division of fordham financial management , inc. , pursuant to which we agreed to sell an aggregate of 750,000 shares of our common stock in a firm commitment underwritten public offering at a price per share to the public of $ 18.00. the public offering closed on february 10 , 2021. we received net proceeds of approximately $ 12.5 million and we plan to use the net proceeds for general corporate purposes . we believe that the current funds on hand will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next twelve months . we continue to review operations in order to identify additional strategies designed to generate cash flow , improve our financial position , and enable the timely discharge of our obligations . cash flow the following table sets forth the significant sources and uses of cash for the periods set forth below : replace_table_token_2_th operating activities net cash used in operating activities for 2020 was $ 6,548 , as compared to $ 2,167 for the same period in 2019. this increase in net cash used in 2020 was primarily due to a net loss of $ 10,871 , a write-down of $ 3,400 for excess and obsolete inventory , an increase in income tax benefit of $ 2,139 , coupled with a decrease of $ 907 in prepaid assets resulting from engines imported from japan which had been prepaid in 2019. investing activities net cash used in investing activities for 2020 totaled $ 19 , as compared to $ 338 for 2019 , a decrease of $ 319. the net cash used in investing activities in 2020 was attributable to a slight increase in new manufacturing equipment . financing activities net cash provided by financing activities totaled $ 5,373 for 2020 , as compared to $ 295 used in financing activities during 2019 , an increase of $ 5,668.

