The icon for both solar panels and accumulators in the electric network GUI only seems to show the top left quarter. Harmless, but annoying.
Also great mod! Out of all the other extended solar mods, this is my favourite.

To fix this:

Unzip mod and navigate to "Advanced-Solar_1.2.1\prototypes\entity"

In each file (except base-entity-updates.lua) you will see a line similar to
icon = "__Advanced-Solar__/graphics/advanced-accumulator/advanced-accumulator.png"

Change the line so that it ends with "-icon.png" instead. Example:
icon = "__Advanced-Solar__/graphics/advanced-accumulator/advanced-accumulator-icon.png"

Thanks, fixed.