Rating of system capacity - MWAC, MWP and MW

Capacity ratings for utility-scale power stations are usually given in megawatts, which for most technologies means AC. However for solar plants this is sometimes expressed in terms of the DC peak capacity of the solar array, and sometimes the AC output deliverable to the grid. Sadly, many sources do not say which!

The Wiki-Solar Database holds both versions, when available.

We have produced this paper with recommendations on preferred terminology and will aim to use this consistently throughout our website and publications.

In general we will try to be specific by using MWP for the DC capacity and MWAC for the AC capacity.

Figures expressed simply as MW can be assumed, unless otherwise stated, to refer to the AC output.

What do we mean by MW?

In most instances, we want to refer to the capacity a plant can deliver to the grid, and we will use MWAC.

Where we use MWp, we mean the DC capacity of the solar array (total rated capacity of all solar modules in the system).

We will try to avoid simply MW, but where we do it should (in accordance with the paper on the left) mean the AC output of the plant, MWAC.

Placemarkers on our maps show output capacity MWAC in red and peak capacity (MWp) in orange.

Output in MW

The power rating of a solar power plant is often expressed in MW. This may be DC or AC capacity - but they aren't the same!

Our placemarkers show both peak and AC capacity when known


The authority on utility-scale solar power