Fitting immersion controller in parallel with timer ?

[liquidity]

Will that really work? Let's say your heater draw 1000 watts and without the heater running you're exporting 800 watts. So the LED on the import meter is on and your widget decides to switch on the heater. But now you're importing 200 watts so the LED on the import meter starts to flash and your widget shuts off the immersion heater. I'm guessing you get the picture - there are scenarios where the heater will cycle on and off like mad. Or have I missed something?

 

[Scobo]

Once the light sensor detects enough light (LED stays on), there's a 5 second delay before the relay activates and another delay when the LED starts flashing before it switches off preventing it from turning the immersion on and off rapidly.
I have it plugged into a timer set to come on around the time we start getting 1.5kw of generation and off around the time it starts to drop below that.
It's not the perfect setup and I'm sure some of the more expensive systems will be more efficient but it was cheap as chips and has provided us with hot water even on dull days.