What is used to measure energy from the sun

Pyranometers

Explanation:

Pyranometers are defined by ISO 9060:1990 as the instruments for the measurement of hemispherical (global) solar radiation for solar energy. Specifically, in the wavelength range from at least 300 nm (10-9 m) to 3000 nm this is often referred to as 'short-wave' solar radiation

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).