That is correct. This is one reason why solar electricity is not so common (in general and not specific to mining).
It is abundantly available and if it indeed were inexpensive, you would solar electricity easily overtaking coal/other non-renewable sources of electricity.
You also need to be aware that the angle and amount of sun they get is going to have a huge impact on how much electricity is collected. Just because a solar panel says it can produce a certain amount of watts doesn't mean it always will. That is under perfect conditions. You will get maybe ,50-75% Depending on how you place it it can be more.
That is true. If you put up a solar panel in Iceland, it probably won't generate any electricity for 4-5 months of the year.
You need to put it somewhere near the equator to generate maximum electricity.
Yep exactly ! That is the other thing the seasons. Even in the UK you will have little sunlight for months at a time so you must factor that in. Hotter conditions be better better for solar energy but does it out weight the extra heat the climate brings ? I think it will since cooling fans are relatively cheap.