Dumb question…

At what $/kwh does a hybrid grid-tied DIY solar system make sense?

Depends on cost of system and how much the utility pays for surplus

Agree with above
AI: says if DIY then when rates are $0.15/kWh or higher
but best if much higher than that due to
hail damage = "poison" cleanup (Houston news item)
re-roofing extra costs under the panels (some say EZPZ)
degradation of the system over time, even if cleaned (owner reports)

Only a few of our Clients have designed new house ready to plug into solar ... with roofs best oriented (mostly those retiring from the energy biz) but none have "plugged in yet" after a decade.
That said, I walk by daily new overpriced tract.houses that sport panels on steep 2nd floor compo roofs.

Since the 70's, we've been promised silicone solar shingles and still today only Schulte has anything close to that.

Residential rooftop solar in Texas could potentially make sense when you are looking at significant investement to run a line to your property, or if your goal is to be 100% off-grid.

Outside of that, only do it if you want to feel good about it - it's not a wise economic decision.