all other things being equal, polycrystalline panels would produce 1% less power at the elevated temperature. But that is a very different thing from saying it would produce 1% less energy over a year of operation. It’s not hot and sunny all day every day; in fact conditions to produce a 70C operating temperature are rare. The energy penalty from choosing polycrystalline solar panels over monocrystalline would depend on climate, but will be far less than 1%. Although there would be a penalty, it’s pretty marginal.