An insurer may so deposit cash or eligible securities in an amount exceeding its deposit required or otherwise permitted under this chapter, such excess deposit to be held for the protection of such insurer's policyholders and creditors. During the solvency of the insurer any such excess deposit or part thereof shall be released to the insurer upon its request. During the insolvency of the insurer such excess deposit shall be released only as provided in section seven of this article.