The commission, headed by retired Kerala High Court judge G Sivarajan, will examine whether the government suffered any financial loss due to the alleged deals.
The case relates to duping of several persons by the two prime accused Saritha S Nair and Biju Radhakrishnan after promising to install solar power panels for them.
While Saritha was granted bail recently after being behind bars for some nine months, Biju Radhakrishnan is still in jail.
After the scam broke out, the opposition had demanded resignation of Chief Minister Oommen Chandy as the names of two of his personal staff had come up during probe.