We are seeing more 104F days here at 5600 feet in AZ in the summer now. That makes it near 118F in Phoenix.
When I lived down there I got used to it and anything less than 110F was OK to work outside, but over that, it was dicey. Now I'm a wimp.
I'm struggling health wise this winter but have been doing some planning for my PV upgrade, needed for the inverter, which is intended in part to run a water chiller for my home in-floor PEX system.
Starfire had an interesting posts earlier about the relatively fixed voltage of PV panels at low light level that woke up some brain cells and I did some further reading on the web about the typical PV voltage vs current output plot. Seems the whole power point tracking business is largely marketing hype, as about 36V (for the nominal 24V PV panel) is always where the sweet spot is within a few percent. That is true regardless of light level. My system is 120VDC and without much thinking about it I used 5- 24V panels in series. That puts the max power voltage at 180V, which wastes some power at my linear PV charge regulator (BIG heatsink- 10x12 inch finned aluminum) when bulk charging at say 146V. Not as bad for heat as seems as voltage is pulled down by the battery load all during bulk charging. Presently about 5.2 amps peak charge in winter, and 6 amps in winter.
Today it was a relatively clear sky, so I tried a test. With 5 panels in series, I was bulk charging at 5 amps. With 4 panels, 4.7 amps. (Peak power voltage of 144V minus wire losses at the panels.) That's only a 6% loss in charging power for 20% reduction in PV panels. So now I'm seriously thinking of adding 4 panels strings in parallel, instead of 5. This will help reduce heat dissipation at the linear charge regulator as the bulk charging current tapers off and the regulator must drop excess voltage, and will get me more bang for my buck on the additional PV panels.
So I may look for some bargain 175ish watt size panels and add 8 of those instead of 5- 300ish watt panels.