On the History page

The Solar Energy units are Langley (Ly). 

This is ..a unit of solar energy equal to:

    - one calorie per square centimeter.

    - 11.62 W-Hr/sq-meter

    - 1.028 W-Hr/ sq-ft

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Notes on the History plots.

As with all the history plots there are verticle lines every eight hours.

There is a tick mark extending below the base line to signify midnight.

The other verticle lines are at 8:00AM and 4:00PM.