This document discusses the role of green banks in facilitating private sector investment in clean energy by reducing barriers through standardization and collaboration. It outlines four phases of market support moving from government subsidies to fully private financing. Green banks can help accelerate this transition by developing standardized processes and sharing performance data to demonstrate the viability of clean energy investments at scale. This increases transparency and allows private capital to access larger and more cost-effective public markets. The document proposes that green banks work together across states through standardization of contracts, underwriting guidelines, and program structures to further reduce costs and risks and attract more private sector capital into clean energy markets.