Disclosed is a colored heat transfer fluid, the heat transfer fluid comprising a nonconductive colorant and having a conductivity of less than 200 μS/cm. Also provided is an assembly comprising an alternative power source and a heat transfer system in thermal communication with the alternative power source, the heat transfer system comprising the disclosed low conductivity colored heat transfer fluid. In addition, a method of making a colored heat transfer fluid is disclosed wherein the disclosed nonconductive colorants are added to a heat transfer fluid having a conductivity of less than 200 μS/cm.