Effects of extreme temps on solar panels
This answer on Chemistry.SE lists the three major factors which lead to solar cell degradation:
- UV exposure
- Mechanical damage
Specifically for temperature:
- High temperatures reduce the internal shunt resistance (lowering efficiency), and contribute to degradation of the anti-reflective coating
- Thermal cycling also degrades the coating and can stress other components of the system (causing cell cracking, flexing, delamination, etc)
A few specification examples
I went on Home Depot's website and pulled up specifications for the first five brands listed by searching "solar panel." Here's what I found regarding temperature specifications:
- Grape Solar (pdf): -40C to +85C
- Ramsond: "resilient to ... extreme temperatures"
- Wagan Tech: no specs for panels, but inverter limited to 0C to 40C
- Goal Zero: no specs listed
- Nature Power: no temperature specs listed
Let's assume that Grape Solar has not exceedingly outperformed the industry average with their temperature rating: at 40C, you are well within the limit.
As for thermal cycling, in the winter this may be an issue due to cold nights followed by warm sunshine. Since this will occur anywhere in the world to some level, resistance to its effects will be built in to any panel.
In your case, you may want to use light duty aluminum frames (which wouldn't be rigid enough to flex the panels when they contract) and/or rubber gaskets at attachment points to reduce the impact of thermal cycling.
Assuming you will install chargers, batteries, and inverters inside the home, extreme outdoor temperatures shouldn't affect the performance of these items.
For cabling you will want to make sure and use outdoor rated types, for which extreme temperatures won't be an issue.
Snow cover, obviously, will reduce panel output. Though your output will be reduced in the winter anyway, it's probably a good idea to clear the snow off periodically to reduce the payback time. As noted in the comments, you may even consider giving the panels a bit steeper of a tilt to prevent snow accumulation.