Question

Why is the box of solar water heater is painted black from inside?

Answer 1

because dark colours are good absorber of heat . that's why box of solar water heater is painted black from inside

Answer 2

In solar water heaters, a pipe of copper with its outer surface painted black is fitted in the form of a coil in abox which is painted black from inside. ... Like solar cooker, the box of solar water heater is also covered with a glass sheet to entrap the heat insidethe box.