All that gas can't help you but solar might
Being gassed up means to have an inflated sense of worth. In this scenario, gas really isn’t going to help these rappers, but the “sun” might. Lupe goes into more detail in the next few lines with the sun/son wordplay.
Second meaning is that fossil fuels are finite and will run out. Whereas solar (the sun), in human terms, will last forever.
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