8. Restricted Cash and Investments

Restricted cash and investments consisted of the following at December 31, 2018 and 2017 (in thousands):



	2018		2017
Restricted cash	$	139,390	$	50,822
Restricted investments	179,000		373,961
Total restricted cash and investments (1)	$	318,390	$	424,783

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(1)	There was an additional $19.7 million and $11.1 million of restricted cash included within “Prepaid expenses and other current assets” at December 31, 2018 and 2017, respectively.

At December 31, 2018 and 2017, our restricted cash consisted of deposits held by various banks to secure certain of our letters of credit and other deposits designated for the construction or operation of systems projects as well as the payment of amounts related to project specific debt financings. Restricted cash also included certain deposits held in custodial accounts to fund the estimated future costs of our solar module collection and recycling obligations. See Note 15. “Commitments and Contingencies” to our consolidated financial statements for further discussion relating to our letters of credit.

At December 31, 2018 and 2017, our restricted investments consisted of long-term marketable securities that were also held in custodial accounts to fund the estimated future costs of collecting and recycling modules covered under our solar module collection and recycling program. As necessary, we fund any incremental amounts for our estimated collection and recycling obligations on an annual basis based on the estimated costs of collecting and recycling covered modules, estimated rates of return on our restricted investments, and an estimated solar module life of 25 years less amounts already funded in prior years. To ensure that amounts previously funded will be available in the future regardless of potential adverse changes in our financial condition (even in the case of our own insolvency), we have established a trust under which estimated funds are put into custodial accounts with an established and reputable bank, for which First Solar, Inc.; First Solar Malaysia Sdn. Bhd. (“FS Malaysia”); and First Solar Manufacturing GmbH are grantors. Trust funds may be disbursed for qualified module collection and recycling costs (including capital and facilities related recycling costs), payments to customers for assuming collection and recycling obligations, and reimbursements of any overfunded amounts. Investments in the trust must meet certain investment quality criteria comparable to highly rated government or agency bonds.

During the year ended December 31, 2018, we sold certain restricted investments for proceeds of $231.1 million and realized gains of $55.4 million on such sales as part of an effort to align the currencies of the investments with those of the corresponding collection and recycling liabilities and disburse $143.1 million of overfunded amounts. During the year ended December 31, 2016, we sold certain restricted investments for proceeds of $118.2 million and realized gains of $41.3 million on such sales as part of a separate effort to align the currencies of the investments with those of the corresponding collection and recycling liabilities.

See Note 11. “Fair Value Measurements” to our consolidated financial statements for information about the fair value of our restricted investments.

The following tables summarize the unrealized gains and losses related to our restricted investments, by major security type, as of December 31, 2018 and 2017 (in thousands):



	As of December 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Foreign government obligations	$	73,798	$	14,234	$	235	$	87,797
U.S. government obligations	97,223		416		6,436		91,203
Total	$	171,021	$	14,650	$	6,671	$	179,000



	As of December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Foreign government obligations	$	127,436	$	62,483	$	—	$	189,919
U.S. government obligations	174,624		12,944		3,526		184,042
Total	$	302,060	$	75,427	$	3,526	$	373,961

As of December 31, 2018, we identified six restricted investments totaling $87.4 million that had been in a loss position for a period of time greater than 12 months with unrealized losses of $6.4 million. As of December 31, 2017, we identified six restricted investments totaling $107.7 million that had been in a loss position for a period of time greater than 12 months with unrealized losses of $3.5 million. The unrealized losses were primarily due to increases in interest rates relative to rates at the time of purchase. Based on the underlying credit quality of the investments, we do not intend to sell these securities prior to the recovery of our cost basis. Therefore, we did not consider these investments to be other-than-temporarily impaired.

The following tables show unrealized losses and fair values for those restricted investments that were in an unrealized loss position as of December 31, 2018 and 2017, aggregated by major security type and the length of time the restricted investments have been in a continuous loss position (in thousands):



	As of December 31, 2018
	In Loss Position for Less Than 12 Months				In Loss Position for 12 Months or Greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Foreign government obligations	$	41,335	$	235	$	—	$	—	$	41,335	$	235
U.S. government obligations	—		—		87,401		6,436		87,401		6,436
Total	$	41,335	$	235	$	87,401	$	6,436	$	128,736	$	6,671



	As of December 31, 2017
	In Loss Position for Less Than 12 Months				In Loss Position for 12 Months or Greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government obligations	$	—	$	—	$	107,731	$	3,526	$	107,731	$	3,526
Total	$	—	$	—	$	107,731	$	3,526	$	107,731	$	3,526

As of December 31, 2018, the contractual maturities of our restricted investments were between 11 years and 18 years.