Average system size

Can someone explain to me what Average system size kWh/kW means.
And how to read the efficiency in the live view

The efficiency simply shows how much each 1kWp of installed panels has produced that day. The higher the figure, the more efficient the system has been.

I’m not sure what you’re referring to.

When you look at either the “Generation” or the “Efficiency” views from your home page, there are 5 pertinent columns (Size, Generation, Efficiency, Average, Outputs). Ignore the “Name”, “Location”, “Seen” and “Health” columns in this instance. The “Efficiency” column is expressed as kWh/kW - not Average system size as you stated above. The “Average” column is the average generated energy per day (kWh/day). This can be arrived by dividing the “Generation (kWh)” column by the “Outputs (days)” column. When you take the “Average (kWh/day)” column, and divide it by the “Size (kW)” Column, you will arrive at the “Efficiency” column (kWh/kW) per day. While this works well for a majority of systems, it is not completely accurate as you will see when you do these calculations. One reason is that not all systems stay the same size throughout the system’s life on pvoutput.org and not all systems are reporting 100% constantly. I made a suggestion years ago regarding this and to consider changing the “Efficiency” to daily generated energy per panel divided by the power rating of the panel and then averaging the panel efficiencies for that particular system but this would complicate things quickly.