Solar Powered/Fallout: New Vegas

Solar Powered is a perk in Fallout 3, Fallout: New Vegas, and Fallout 4.

Fallout 3 and Fallout: New Vegas
With this perk, you gain an additional 2 points to Strength when in direct sunlight, and slowly regenerate lost health at a rate of 1 HP every second. Unlike Night Person, which operates both indoors and out, this perk only operates outdoors. It is in effect between 6 AM and 6 PM. It synchronizes well with Rad Absorption for healing minor health damage and minor radiation poisoning while exploring or fast traveling.

Fallout 4
With the first rank of Solar Powered, Strength and Endurance are increased by 2 between the hours of 6:00 AM and 6:00 PM. The second rank slowly reduces accumulated radiation damage, and the third rank slowly restores lost health while in the sunlight.