This is quite a hard topic. If you look for solarpunk clothing online, you'll find fashion clothing mostly in green and with leaf patterns or such, like this, but I find this to be too unrealistic, as most designer fashion, in the sense that nobody would wear that in a daily context.

But actual wearable solarpunk clothes, at least for me, would be a mix of work-focused very resistant clothing, like this work overalls or this cargo pants, with a mix of weather thoughtful pieces of clothing, like this cross pants, which are quite fresh while protecting your legs from scrapes, or, if you lean more into breaking the gender-norm, some long loose dresses are quite comfortable, specially in hot weather (and the flow is so nice!)

In my opinion, any durable and useful piece of clothing can be considered solarpunk, even more if it is field-work or nature-oriented, like mountain boots or cargo pants (also, any patched clothing does the trick, although it's best that it happens organically rather than buying it). And as a final personal note, I find colourful or patterned clothes quite nice when they're not overwhelming, so for example cross pants or a loose oversized shirt, although it is quite uncommon in male clothing (I could not find a picture of T-shirt and shirt other than with the flannel shirts or plain ones) and I'm not sure how environmentally friendly cloth dye is (but the same could be said about the clothing industry altogether). Hope this helps, even if just a bit :)