The development of wireless power transmission technology is important for both space-based exploration and energy applications on Earth. To further this technology, a small-scale wireless power transmission system, consisting of a laser and photocell, was developed to set an end-to-end system efficiency world record. Key efficiency gains were made by acquiring highly efficient components, matching laser wavelength with the photocell bandgap energy, and precisely controlling component temperatures between 298 K and 78 K.