I don’t think it makes sense to compare those efficiencies, as one is for converting heat to electricity, while the other is for converting sunlight. If you use sunlight to heat water and then use that for a steam turbine, the efficiency is similar to a photovoltaic panel. The efficiency numbers are still useful, but only when they refer to the same starting point for the conversion (e.g. only comparing things that turn heat into electricity).












I remember seeing a documentary about a village in Germany, where many houses were damaged by geothermal plants, caused by water entering layers where it usually didn’t reach and the material there taking in water and expanding. So it probably depends a lot on the local geology and also on the depth. I sadly don’t remember how deep the one in the documentary was.
I know a few people that got geothermal heating installed for their homes (in Germany), which goes a lot less deep than something intended for whole cities or districts. The one at my friend’s home is 50m deep, and it looks like anything less than 400m is considered “near surface”