[pct-l] Phone Charging

[Rod Belshee]

> All things being equal, with only temperature as a variable , solar output 
> is greater when temperature is colder.
> So what is the basis that your output might be greater in summer?

More radiant solar energy is available per square foot in summer time. There 
are fancy graphs of solar radiant energy available, but here are a few 
basics relevant to the PCT thru-hiker:
- peak at solar noon (sun highest in sky), majority of energy is in a window 
just a few hours each side of solar noon)
- strongest at summer solstice, weakest at winter solstice (early May to 
early Sep is good)
- stronger in the south, weaker in the north
- diminished by clouds (full sun is obviously best, though I have been able 
to charge a little on lightly cloudy days)
- open view to sky required (duh)

Because of the last four on the list, chargers in Washington are useless, 
and in most of Oregon they are dubious. But they are great for the first 
1700-1800 miles, especially when you take a siesta in the heat of the day in 
southern California and can charge up rapidly.

Aligning to the sun is also a variable. The available radiation at a 45 
degree angle is about 70% of that when aligned perfectly, and actual panels 
tend to perform a bit worse than that.  Best to keep within 30 degrees, 
where close to 90% of the maximum radiation is available.

So, you are right that all things being equal, cold temperature is better. 
But unfortunately in solar calculation all things are never equal.

-- Steady