Its "green energy certified" label is designed to give users a real guide to who is doing most to source renewable power.
The idea is to reassure householders and small businesses that paying for green energy is actually worth it.
Energy companies are committed to using more renewable power.
Before the introduction of this new labelling plan, a supplier could claim to be helping the environment, but in fact simply be meeting its existing promise to use renewable energy.
Now, suppliers will have to demonstrate to an independent panel of experts that they are taking extra steps to cut their use of non-renewable power in order to merit the "green" label.