Elon Musk and other key figures at SolarCity Corp. (SCTY) have committed to buy $100 million of the solar panel installation company's debt ahead of its planned $2.6 billion acquisition by Musk's Tesla Motors (TSLA - Get Report) .

SolarCity in a regulatory filing late Tuesday said that Musk has committed to buy $65 million of a previously-announced $124 million "solar bond" offering, while SolarCity CEO Lyndon Rive and chief technology officer Peter Rive are to buy $17.5 million apiece. Musk in addition to serving as CEO of Tesla is chairman of SolarCity, and the Rives are Musk's cousins.

San Mateo, Calif.-based SolarCity provides commercial and residential solar panel installation at little to no upfront cost, recovering its costs via monthly payments and sales of unused electricity back to the grid. The business is debt-intensive, with SolarCity listing $3.25 billion in borrowings on its balance sheet as of June 30.

The company has struggled to break even in recent quarters, and prior to Tesla's acquisition announcement some had questioned whether SolarCity would be able to continue to fund its obligations. The deal, involving two companies that count Musk as the largest shareholder, was met with criticism by some but the companies attempted to mitigate concerns by recusing directors with ties to both sides from deliberations and requiring approval by non-affiliated shareholders.

The latest bond sale, which was disclosed concurrent to Tesla's high-profile announcement of a new vehicle battery that should provide better performance, is sure to raise additional eyebrows. Company bulls are likely to see the insider purchase as a vote of confidence, while bears will read it as a sign of the market's tepid interest in buying additional SolarCity borrowings.

The bond deal is believed to be the first time Musk has invested in SolarCity bonds directly, though a third Musk-affiliated company, privately-held Space Exploration Technologies Corp., bought about $90 million of a $105 million debt issuance last year and an additional amount of SolarCity debt earlier this year.

Oppenheimer managing director Colin Rusch, appearing on CNBC Wednesday morning, said he is concerned by the apparent lack of demand for the SolarCity bonds and by "the relationship between SolarCity and Tesla and the return on equity for the Tesla investors here."

Rusch said the hope for Tesla post-deal is that the company is "robust enough" to manage SolarCity's cash needs, noting that there is potential for "significant cash flow off the auto platform." But Tesla also has significant cash needs of its own as it attempts to bring its more affordable Model 3 to market and build out its global retail and charger networks, leading some to predict the company is likely to issue more shares in the quarters to come.

Tesla already tapped public markets once this year, raising more than $1 billion to fund operations in a May secondary.

Ahead of the merger SolarCity is taking steps to cut expenses. The company Wednesday told California officials it intends to lay off more than 100 workers beginning in mid-October, with most of the cuts focused on back-office, legal and accounting functions that presumably can eventually be taken over by Tesla employees.