One of the many mysteries behind the share price collapse of the solar panel maker controlled by Li Hejun is this: Which of the Chinese billionaire's many creditors risk losing every yuan they put into his company?

A plethora of lenders are exposed to Hanergy Thin Film Power Group Ltd and its parent company, including Industrial and Commercial Bank of China Ltd, which is owed tens of millions of dollars.

On May 20, about 47 percent of Hanergy's market value vanished in minutes and it is now under investigation by the Hong Kong Securities & Futures Commission.