Certificates are principally used to disclose to consumers the source of energy, and thus the environmental impact of energy production, to consumers; and can be used to demonstrate to government the achievement of national targets.

They can also be used to enable many types of support schemes, whether voluntary (green energy and green label schemes); or obligatory (such as supply obligations, portfolio standards and feed-in systems). They do so by enabling source of the energy to be guaranteed, and can be traded internationally.