About $190m has been raised by the renewables company through the sale of 12.9m shares in SunEdison Semiconductor, while a further $400m has been secured through credit commitments from several financial institutions.
The $590m proceeds will be used to fund the cash portion of the upfront consideration to purchase First Wind.
In November 2014, SunEdison signed a definitive agreement with TerraForm Power to jointly acquire First Wind for $2.4bn.
SunEdison chief financial officer Brian Wuebbels said: "These funds are a major step forward in our acquisition of First Wind.
"Our ability to secure this funding, while preserving the upside in value from our ownership in TerraForm Power, speaks to the strength of the growth platform we are creating."
SunEdison said that its upfront portion of the consideration is approximately $1bn, comprising the previously announced $340m seller convertible note and the remainder in cash.
Scheduled to be closed during the first quarter of 2015, the acquisition is subject to usual and customary conditions and regulatory approvals.
Image: First Wind is constructing renewable energy projects in the US. Photo: Courtesy of First Wind.
