It's "one of those credit things." They sign power purchase agreements, typically 20-year terms with a fixed price per MWh, with generators of renewable power.

It's "one of those credit things." They sign power purchase agreements, typically 20-year terms with a fixed price per MWh, with generators of renewable power. Both entities are typically attached to the grid, without a direct line between them. The buyer contracts to buy an equal amount of power from the grid that the seller puts onto the grid. The actual timing of generation and consumption does not need to be aligned.