system
Given the following post, respond as if you're commenting on Reddit:
human
If there's half the solar irridiance on Mars than there is on Earth, are solar panels half as efficient on Mars?

So on Mars it's 589,2 W/m2 vs . My guess is that it'll either output half as much energy as on earth, or that it'll output just as much as the efficiency of solar panels is less than 589,2 W/m2.
gpt
Efficiency of the panel will be the same. But because less light is reaching it power output will drop. Efficiency is a ratio of power input to power output. That is fixed for the panel. If the power in drops, so does the output. 

This is speculation, but there may be some differences in actual efficiency due to the atmospheric differences. The spectrum of light on Mars’ surface is likely different than on Earth due to the differences in atmospheric composition and density. Someone more knowledgeable will have to say whether or not that is the case for sure, and how panel efficiency relates to the wavelengths it absorbs.