Used a reputable, local company that employs their own installers. Workmanship guarantees for 10 years (a bullshit company won’t offer any of that) No money down, got a loan and amortized it when the federal tax credit came in (currently 30%). Company also handled all the paperwork- I didn’t have to talk to the power company once. My roof was only a year old- panels generally have 20-25 year warranty so you’ll want your roof to outlive that.