I wouldn't give much credence to that report, as there is no demonstrated understanding of PV site installation management principles (e.g. bright ground treatment). They deliberately highlight a worst case scenario (covering 20%+ of the entire Sahara in unmanaged high density PV) and shove a quick note at the end saying that they modeled 5% and even without other mitigations that was fine. Their model also doesn't include the carbon offsets at all, so it's absolute worst case and entirely unrealistic.

With proper site selection and albedo managed via density and bright ground treatment, you can expect net neutral local heat impact.