Current only diverter.

I've been looking at building a box to turn on my immersion heater when there is spare power.

My plan was to measure the current coming from the PV system and also the current being used by the house.  Then compare the two and switch on the immersion heater if the PV current is 12A above the house current.

This seems to be different to the normal way of just measuring power at one point.  Is my idea flawed or just more expensive?   If it will work, I like the idea of being able to track generation, usage and feed in separately.


Robert Wall's picture

Re: Current only diverter.

Your idea is, I think, the original method of measuring the power. It was superseded by the single CT method that does the subtraction in the wiring itself, thus it is much more accurate. There are two well-proven designs published here, and Robin's is also available as a kit or as a pre-built and tested unit from his website. Both these designs control the load so they are effective from (almost) zero surplus energy up to the maximum your dump load can accept, it's not necessary for the full 12 A to be available before surplus energy is dumped into the heater.

Cancelor's picture

Re: Current only diverter.

I see :)

Many thanks.

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