Sunpower has been used primarily for heating and to generate electricity. These two processes are antithetical and involve two different spectra of light.

Objects are heated by infrared radiation, which has such long wavelength that it cannot penetrate atoms of material, but rather shakes them, giving rise to molecular motion or heat. But shortwave ultraviolet radiation can penetrate atoms to shake the electrons, and this can be transformed into electrical power.

But little or no attention seems to be given to filtering the sunlight to get "its best part for the given job". Either for heating or electrical generation, "polluted" sunlight is used, mixing the work-effective radiation with non-effective, even inhibiting radiation.

For HEATING, use A FILTER ALLOWING FLOW OF ONLY INFRARED RADIATION. For ELECTRICAL GENERATION, use A FILTER ALLOWING FLOW OF ONLY ULTRAVIOLET RADIATION.

See if this doesn't increase the efficiency of the given devices.