When talking about solar cells, the efficiency is defined as electrical power produced divided by the solar irradiance on the panel (~1000 W/m^s without concent

When talking about solar cells, the efficiency is defined as electrical power produced divided by the solar irradiance on the panel (~1000 W/m^s without concentration). In this situation, the theoretical limit for a single junction solar cell on Earth is ~34% as shown by Shockley-Queisser in their detailed balance calculations. Multijunction cells can be more efficient than single junction cells and can theoretically reach ~70-80% efficiency if >30 junctions are used and concentrated sunlight is used. In practice it is prohibitively difficult and expensive to make a device with more than 4 or 5 junctions, so you will not see one sun efficiency greater than 70% in real life. The 95% number is for a Carnot engine and doesn't apply to an operating solar cell. In order to extract power from a solar cell, you need to operate it in forward bias (typically at the maximum power point). When at the maximum power point, the solar cell emits radiation and therefore has irreversible losses. This is why the real limit for a single junction cell is 34% and not 95%.