The sun shines on a photovoltaic panel and it makes electrical energy, presumably by absorbing the photons in the incident light.
But where does the energy transferred into electricity come from? Does solar electricity make the earth a little darker, or a little cooler, for example?
If it does one of those things, how much electrical energy would we need to generate to make an observable change in the environment?
As already mentioned in the comments, the energy comes from the absorbed photons. A photon has a frequence-dependent energy
$$E=hf$$
where $h$ is Planck's constant and $f$ is the frequency.
Being sunlight, these photons come from the sun. For more information, you might want to refer to Light formed by the sun? and The source of the light we see from the Sun.
As already mentioned, photons are converted to electricity by the panels. This does absorb a small amount of light that could have been absorbed, reflected, or refracted back into Earth's environment. But the electricity produced by the panels is not stored permanently. When it is used it is mainly converted to light or heat. So, long term, all of the energy converted by the panels returns to the environment. No energy is truly lost.
