Solar Solar Iboost diverting electricity to the hot water tank

[pob1976]

Hi, I have a Solar Iboost and I understand that when I export electricity, it gets directed to the hot water tank. Is it supposed to be directly heated by solar, or does the mains add to it along with the solar? My smart meter is showing that I am using 2kw when the Solar Iboost is diverting electricity to the tank. The screen on the Iboost says heating by solar, but that is not the case if its drawing 2kw as well.