Unexploited Photons: What Happens to Solar Energy?

[Kyurius]

While I’m waiting until I can afford some photovoltaic panels, I wonder what is happening to all the photons pummeling my roof now?
If the (light) energy from one square cm of solar radiation is converted into electrical energy and then converted to heat by Aunt Matilda's blow-dryer, what would have otherwise happened to the energy from those same photons - if Matilda had not hired Green Inc. to install all those shiny, black rectangles on her roof?
Would they have been absorbed by the roof? If so, presumably they would not make Matilda's house glow in the dark. So, they would somehow be transformed into heat, or some other form of energy?
Would they have bounced back into space, taking their energy with them?

 

[NobodySpecial]

Would they have been absorbed by the roof? If so, presumably they would not make Matilda's house glow in the dark. So, they would somehow be transformed into heat, or some other form of energy?

They would have heated the roof and the energy gone into heating the Earth, the Earth would then have emmitted that heat as infrared photons back into space

 

[Drakkith]

The photons are either absorbed or reflected by the roof. Those that are absorbed will heat up the roof, which will release photons as infared radiation. We can't see the wavelength of light that is in the infared range with our eyes, but there are several instruments that can see it and turn it into a picture on a screen for us to interpret.

Those that are reflected take their energy with them to be absorbed or reflected elsewhere. Note that this only applies to visual and infared photons. Longer and shorter wavelengths are still absorbed or reflected, but can have different effects other than simply heating something. UV light has enough energy to strip electrons off of atoms and ionize them, which is what causes sunburns and breaks down certain materiels such as plastics and paints. (Which is why things that are left out in the sun tend to fade over time)