Solar wired into CU breaker, why should it use the solar power & not pull from the grid?

Bignose2 · Jul 8, 2022

Hi,
Really just for info. not a problem or anything.
(to be honest also wanting to be sure it is taking from solar as much as possible & can you be sure of that?)
I assume the new solar meter is actually what is being drawn from the array so is an accurate indications of that.

Grid tied 4kw solar, no batteries. Just been installed.

Sorry for perhaps a stilly question & the installation may have something I don't know about but I cannot work out how/why the house will use power from the Solar generations first as opposed to using the grid or a bit of both.

As far as I can see the inverter connects via isolators & the generation meter & simply into the CU on its own MCB (rcbo)
Why when I turn a kettle on should it use that power instead of drawing from the DNO meter & grid.

Thanks I/A

littlespark · Jul 8, 2022

Not at installer myself, but what I had explained to me… several years ago now.

The inverter measures the voltage coming from the mains and outputs the solar generated a couple of volts higher.

This pushes against the mains voltage and the house devices use the higher PV generated by the sun.
Any PV generated is measured by the meter only coming from the inverter… not going up to the inverter

Any excess PV electricity basically leaks out to the “grid”

plugsandsparks · Jul 8, 2022

As LS says, under normal conditions the Solar inverter will seek to dump its power anywhere, it does this by raising the voltage. If you have the kettle on Solar gets first dibs as it is competing with the grid for your kettle load. As the grid voltage is largely a sitting duck wrt Voltage, its easy for the Solar to win the battle as to who supplies the kettle.
however sometimes the solar can only provide a portion of the power at which point the grid strolls up fills the gap.
its all magic really, but rest assured if your inverter is showing "generating" or its operation light is Green (depends on make of inverter as to what is normal operation) then your solar will be maxxing out saving the planet.
cheers
P&S