Single pane windows, would shutters be a frugal fix?
To be frank, I'm not sure if replacing the single pane with double pane is: A - something I can afford at the moment and B - something I can DIY (which adds to point A).
I have a feeling that the windows are a large part of my electricity usage (due to AC constantly running), I have them "foiled" and really tempted just to board them up. Before I go to that extreme, I was thinking maybe there's something I can attach to the outside that would essentially add that 2nd pane, or at least block some sun from hitting the glass.
Storm windows are a thing in four season climates, basically just another pane of glass over the existing window in winter. I have known low income people to just staple clear plastic over the frame for the same effect. You might give it a try. Ugly, but better than boarding them up.
I think shutters (preferably white) would probably help on south and west facing windows. I don't really see them used much down here; the ones I do see are fake. Highly reflective silver tint (applied on the outside) helps more than dark tint. Window awnings would also help. Large trees are the long-term solution :)
Shutters won’t help much. Storm windows are the cheapest help. We just slowly replaced them (exit: the windows with double pain, has filled, vinyl with UV coating) ourselves ($250-300 each at a big box lumber store).
Windows are usually towards the end of the list of things to upgrade. What's your insulation situation like? Attic, walls, ductwork? Have you done a leak test to see where conditioned air is escaping? Has your AC been serviced and in good operating order?
I'd check all those out before replacing windows. As other poster suggested. Especially if you have windows that are in good condition otherwise.
FWIW, I’ve heard that if you let vines grow directly on the exterior (or if you run cables and plant the kind of vines that need to climb cable), the vegetation will insulate/shade the house from the extreme sun.
I can’t say it’s 1st-hand knowledge but perhaps worth looking into. Evaporatie cooling might have a small role in that too. Of course the caveat is if you let vines grow directly on the stucco, they will destroy the stucco which many folks consider a bad trade-off. The other caveat is plantlife brings insects so you might not want to bring insects right up to your walls.