How can I reduce the sun reflection size?

I am making a level on Pluto for Planetary Settlers, but I cannot figure out how to reduce the sun reflection from the sky box. You can barely make out the sun here, but the reflection off the solar panel roof is “blinding”, and way too bright. How can I reduce the reflection size and brightness to match the smaller, dimmer sun?

Using solar energy allows you to reduce your dependence on traditional energy, and alternative solar energy is safe for the environment.