NEW YORK--(BUSINESS WIRE)--Kroll Bond Rating Agency (KBRA) assigns preliminary ratings to two classes of notes from Sunrun Callisto Issuer 2015-1, LLC, Series 2015-1, a residential distributed generation solar securitization. This transaction is Sunrun Inc.’s inaugural securitization. The transaction is secured by 7,893 photovoltaic (“PV”) residential solar installations and related contracts. Approximately, 68% and 32% of the contracts are in the form of power purchase agreements (“PPA”) and l