I’m wondering what is the mechanism the system uses to cut out during a power cut.
If it’s already feeding power back through the grid, when there is a power cut how does it detect that ??
When the inverter shuts down either during a grid power outage or excess wind, does it power itself back up again automatically when power is restored or is manual intervention required?
It's both voltage and frequency. On very windy days I find mine shutting down. I don't know if it's because of the frequency or voltage, my monitoring isn't catching it.
It's likely the inverter will shut off before the grid actually goes down, once the grid falls out of spec, inverter will shut off.
When there is a power cut, there will be a transient when the voltage/frequency drops, the inverter will see that and disconnect.
Generally inverters are DC powered (directly from PV)
It's built into all grid tied inverters.
I suppose what I was asking is what measurements does it use ??
Voltage and frequency??, if the inverter is feeding back on the lines coming into the house how does it know if the grid is down ?, there’s nothing feeding into the house but rather the house is energising these lines.
is it looking at impedance on the supply side ??
Most people dont have an alternative power source for the spring loaded switch. There might even be some rule against having such a set up
What surprised you? Don't half think about solar it's a no brainer. Best investment you will make unless you are aged 85+!
As someone who's half thinking about installing solar but knows nothing about it, this surprised me when I heard about it happening a neighbour.
Why would it ever be set up that way?
Ach, I didn't really want to get into the specifics......it was more just trying to answer the original question and I'm sort of sorry I attempted it now. But yeah, there are a couple of different "areas" for lack of a better word inside your inverter. Most hybrids have 2 inverters inside the box. When the grid goes down, a lot of the inverter box (as a unit) is dark. Yes, many of them as I mentioned have an EPS outlet, and people have hooked that into the consumer unit via a changeover, but it's an edge case.
95+% of people don't have a changeover switch that or use the EPS - so for them, when the gird is down, the inverter is effectively down as it's powered by the grid.
I'm not sure what you mean, I had a power cut earlier and with my change over switch and batteries I ran what I needed. When you say "so when the grid is gone......it goes dark itself" what are you referring to? The inverter?
100% mate - and that why I was saying there's a couple of different aspects to answering the question.....
I’m wondering what is the mechanism the system uses to cut out during a power cut
The edge case is as you know the inverter can be powered in a limited capacity via the batteries etc, (EPS feed, or even the whole switchover that some people have to their consumer unit) but that's probably outside the scope of the question. The main thing is that it's powered by the grid itself, so when the grid is gone......it goes dark itself.
Inverters don't need the spring loaded switch though. It's more of an issue of isolation (generally fire) where the DC cabling usually is coming into the attic, and hard to get to.
It does not actually form part of the anti islanding function on the inverter
Couple of different aspects to your question. The solar panels themselves have a spring loaded switch, which is held closed when there is grid power. When the grid drops, the spring opens the circuit and cuts the power coming from your panels into your inverter.
The inverter itself is a "grid-tie-in" inverter (general case here), and it's constantly looking at the voltage and frequency of the power coming in from the grid. It's not different from your telly, or oven in respect to that it's powered from the grid, not the solar panels themselves. So when the grid goes, it's got no power, so it shuts down.
