For private grants, you may want to check the Foundation Center's Foundation Grants for Individuals Online. It's a subscription based website ($9.95 per month) but their opening blurb only says that the database is ideal for "students, ...
John Converse Townsend, a Forbes contributor, shares what can the private sector do for a social enterprise. He encourages social enterprises to reach out to corporations for help to scale up their businesses.
Business Grant Application Process | Personal Government Grants