Glossary

MW and MWh

Also: megawatt, megawatt-hour, MWac, MWdc

A plant's power (megawatts) and a battery's stored energy (megawatt-hours); a solar farm's size in AC and DC differs.

Megawatts (MW) measure power: how much a plant can deliver at once. Megawatt-hours (MWh) measure energy: a 100 MW battery that can run for four hours stores 400 MWh.

Solar farms are sized two ways. The grid queue gives the AC capacity, what the inverters deliver to the grid; the panels themselves add up to more DC capacity, often 20 to 35% more. Groundtrace reports the AC megawatts the queue or the EIA gives, so the panel count, the piles and the acreage scale with a somewhat larger DC figure.