How it works
A buyer takes its consumption for each hour and compares it with carbon-free supply delivered in the same hour on the same grid. Surplus in one hour cannot cover a shortfall in another. The result is a score, the share of the year's consumption matched hour by hour. Carbon-free sources include wind, solar, hydro, nuclear, geothermal and storage charged from them. Some methods also count the carbon-free share of the grid mix in each hour.
It needs hourly meter data and hourly certificates, which some registries now issue under standards such as EnergyTag's. The supply portfolio changes shape. A buyer adds wind for the night, storage to move solar into the evening and firm sources for still weeks, and accepts surplus in some hours. Costs rise as the score climbs, and the last few percent cost the most.
Why it matters
Annual matching lets a buyer claim 100% renewable supply while its night-time load runs on fossil power. Hourly matching closes that gap, and accounting standards may move toward it. The price is a harder procurement problem. The cheapest megawatt-hour stops being the target, and the shape of supply against load becomes the measure. Developers who can sell shaped supply from hybrids and storage find buyers willing to pay for that shape.
A worked example
A site uses 10 MWh every hour, or 240 MWh a day. Solar delivers 240 MWh across 10 daylight hours, 24 MWh an hour. Volume matching scores 100%. Hourly matching counts only 10 × 10 = 100 MWh, a score of 100 ÷ 240 = 42%. A battery shifts 80 MWh of the 140 MWh surplus to the night at 88% round-trip efficiency, adding 80 × 0.88 = 70.4 MWh. The score rises to 170.4 ÷ 240 = 71%.
Illustrative figures.
Across markets
In the US and Europe, hourly matching is spreading through voluntary corporate targets. EU rules for renewable hydrogen also require hourly matching from 2030, after monthly matching until then. India has no hourly certificate system yet. Its round-the-clock and firm and dispatchable renewable tenders instead require shaped supply with minimum availability, which pushes procurement in the same direction.