Solar Attic fans a waste of Money??

Looking at the description of almost every solar attic fan, they like to say "Up to XXX CFM"
They only produce that rate when the angle of the sun is optimal.   In the morning, and more importantly, in the later afternoon and evening, they ramp down the wattage produced, and so the speed of the fan.   At 8:30pm (when the roof is still more than warm after a warm day), it's not moving much at all.

On top of that, even the max rated "Up To" CFM is lower on most of these fans than is recommended for an average sized attic.
My attic happens to be fairly small.  The typical Solar fan - at its max CFM, is still too small for my attic (I probably need around 800CFM).
A fan like this one is rated that highly:
http://www.ussunlight.com/products/solar-attic-fans/1010tr
(They go out of their way to state the CFM, but another site says it's max is 850)

But given overcast Portland - even on a lot of Summer days (and, like I said, the issue with evenings), I don't have a lot of faith.
Solar companies are pretty abusive about the numbers they quote.  They love to put out maximums, but have no guides to realistic performance expectations.   When you have solar panels spec'd out for a roof, there's all sorts of analyses of angle of incidence, path of the sun seasonally, potential shadow sources.  Cloud cover.  The panel manufacturers don't give you that.  They just say 300W/panel or some unattainable number like that.    It's up to the installers to be informed and inform the customers. 

I think these attic fans might be a particularly egregious case of that because they are most wanted late in the day, and (depending on orientation, location, etc) that might be when they're ramping down.  In NW Portland, the West Hills shade us earlier than the rest of the City by a half hour or more (which sucks, in other ways, but certainly for solar).   The manufacturers say nothing about zero power in the evening.

[Info on CFM capability deleted.  I was wrong.  I cannot find any useful CFM stats for these fans.  Pointed out in the comments.]

ALSO:  Some experts believe attic fans should be weak if used at all.  Stronger fans may pull conditioned air from the home up into the attic.   A moderate fan will remove humidity (the original design function).  Any cooling function will be more limited.   For this purpose a solar fan is possibly adequate.  There isn't enough data I can find to really know.

Part 27 on a Glock is the Controversial "slide stop lever"

Part 27 on a Glock (17, 19, 22, 23 and other integers) is the "slide stop lever"

It looks like a little rectangular button about an inch and a half behind the slide release thingies you pull down when you're taking the slide off the gun.

I never saw anyone use it in videos or at the gun shop.  Yet, it's one of the very few controls on the gun so you'd think it is important.

Googling "slide stop lever glock instructions", it turns out it's a little controversial.  

The uncontroversial use is to hold the slide open when there's no magazine in the gun (when you're working on it or for no reason whatsoever).

You pull the slide back and push up the slide stop lever - and (surprise) - the slide stops.  It stays open.  If there's a magazine in the gun it just stays open with no thumbing of a lever required.

But Part 27 The Slide Stop Lever can also be used to chamber the first bullet when you put in a fresh magazine (The slide is held open after firing the last bullet.  The method you always see and just about everyone uses is to put in a new magazine and pull the slide back and let it go - aka "the slingshot method").   In general people prefer the slingshot, but here's what the manual says:

  After the last round has been fired, the slide remains open. Remove the empty magazine from
the weapon by pushing the magazine catch (19). Insert a new magazine and then either push
the slide stop lever (27) downwards (see photo), or pull the slide slightly backwards and allow it
to spring forwards. The weapon is now again secured and ready to fire.

The weird part is that this is controversial.  For some reason people think you shouldn't use the slide stop lever to release the slide.  There are a number of specious reasons given.   I think the truth is that all pistols can be operated via the slingshot method, but the slide stop lever is specific to Glock and a few other guns.  So gun people are used to the slingshot and just think it's how God meant the gun to be operated.

You can use it to hold the slide open when you have no magazine in the gun with the slide stop lever, but it's pretty hard to push it down to release the slide without pulling the slide back to relieve the friction.  You can do it though.
If it's that hard to do with bullets in the gun (haven't tried it) then I understand why people don't like it -- and why there are after market extended  levers - including one from Glock -  so you can get a little more force on it.

And that's the Saga of the Slide Stop Lever, Part 27.
There are 32 + parts in the naked Glock.  this has been the story of one of them.