Immersion heater auto switch for a PV system

[geoffking60]

Does anyone know of a switch which will automatically switch on my 1kw immersion heater when the output power from my inverter has reached a level of say 2kw and switch off when the power dropped below 1.8kw.
I could then preheat my hot water whenever the sun is shining.

[dirkgently]

I can see a flaw in this cunning plan. 2kW-1kW=1kW<1.8kW

[dickymint]

Deja vu moment then..........

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Can't see as there is a cheap way of doing exactly what you want. Seems to me that you are in the realms of 'Pulsed Logic Control' with all the expense that entails with sensors, timers and monitoring. I daresay there will be Input/Output terminals on your invertor to do this.

PS. are you getting enough output on your system to dedicate a panel soley to an immersion?

[FlossyThePig]

If you want to heat your water using sunlight do it directly with a solar powered water heater. It will be a lot cheaper and more efficient.

[Paul Drawmer]

Set up a separate small PV panel to drive a control circuit. You will have to find by trial and error the switching voltages from your separate panel that correspond with the outputs you require on the inverter.