You might want to adjust this so it comes on after a larger drop - see this thread about only heating hot water when it’s cold for justification. For instance, I put mine on to heat the water at 10am, when a) there’s not so much demand for heating, b) the ambient temperature is higher and c) there’s a good chance of sunlight on the solar panels. I generally find heating it once-a-day is enough.
After a bath and two showers last night, the temperature of our tank had dropped to 12 degrees (!), yet as that’s measured at the bottom of the tank there was still hot water coming out of the top. It was still measuring 12 degrees this morning when the heat pump was then allowed to heat it. Took about 45 minutes to heat the tank up to target temperature again.