TSLA Tesla Inc

A recent bond offering to shore up Solar City Corp. was primarily financed by Elon Musk, the company's chairman, and two of his cousins who are executives with the rooftop solar outfit.

Last week the San Mateo, Calif.-based solar panel installer announced that it would float $124 million in bonds at an interest rate of 6.5% with a maturity date of February 2018. On Tuesday the company disclosed in a filing to regulators that roughly $100 million in bonds were purchased by Mr. Musk, who is also chief executive of Tesla Motors Inc., as well as Solar City CEO Lyndon Rive and Peter Rive, the company's chief technology officer.

Mr. Musk bought $65 million in bonds, while Messrs. Rive each purchased $17.5 million, according to the filing. SolarCity didn't disclose the total amount of money raised by the bond issue or detail how the new funds would be spent.

Mr. Musk and Messrs. Rive couldn't be immediately reached for comment.

This isn't the first time that Mr. Musk has thrown his personal support behind companies he controls. Earlier this month, Tesla and SolarCity agreed to a $2.6 billion deal that would see the home solar company absorbed into the electric car maker.

Mr. Musk, who owns more than 20% of both companies and is the largest shareholder in both, said at the time that the synergies between Tesla and SolarCity—and their joint efforts to create better battery storage—would create a vertically integrated green energy powerhouse. Critics of the merger have lambasted it as self-dealing that bails out the struggling solar panel company and lashes together two money-losing entities.

Mr. Musk's unconventional debt move isn't unprecedented. Space Exploration Technologies Inc., where Mr. Musk is chief executive and lead designer, bought $90 million in SolarCity solar bonds earlier this year. In addition, Mr. Musk has taken out $475 million in personal credit lines to buy shares of SolarCity and Tesla, according to securities filings. Those lines are secured with Mr. Musk's shares in SolarCity and Tesla.

SolarCity has been under intense pressure to slash its expenses and turn a profit after years of losing money. The Rive brothers recently slashed their annual salaries to $1, down from $275,000, as part of SolarCity's cost-cutting measures.

In the second quarter SolarCity reported a second-quarter loss of $250.3 million, or an adjusted loss of $2.32 a share. It has forecast that in the third-quarter it will report an adjusted loss of between $2.55 and $2.65 a share.

Shares of SolarCity closed Tuesday at $23.09, down nearly 55% so far this year. They ticked lower by a few cents in after-hours trade.

Write to Cassandra Sweet at cassandra.sweet@wsj.com

(END) Dow Jones Newswires

August 24, 2016 08:35 ET (12:35 GMT)

Copyright (c) 2016 Dow Jones & Company, Inc.