not connecting them to anything does nothing to the temprature. shorting the panel out electrically would produce heat by the amount of the electrical rating listed on the panel plus the resistance of the internal cells,
Beg to differ:
Once a photon is absorbed, creating an electron-hole pair, some of the photon's energy is changed to the energy represented by the separation of the electron and hole, and the rest went into heating the panel.
Now what do you do with the electron-hole pair:
- You can do nothing: It recombines, emitting infrared (which is absorbed and becomes heat in the panel)
- You can use it to drive an electron through the wiring: Some of the energy goes into the load, some in to the panel resistance, and some into the electron-hole anihalation when a returning electron falls into the hole (across a much lower energy gap).
The difference in panel heating is the energy that was delivered to the load and the wiring beyond the panel.
So disconnecting the load means that 20% or less of your incoming solar energy that WOULD have been delivered to the off-panel load is now delivered to the panel.
So the panel is heated significantly, but not greatly, more WITHOUT the external load. (And the heating of the wiring internal to the panel comes from energy that, without the current, would have been heat in the panel anyhow.)