How fast can an inverter shut off if a relay closes off the grid.

[Andy]

I am in the latter stages of a Victron Quattro install and was going to put a SolarEdge inverter I already own on the output side of the Quattro. In the event of a power cut the idea being that when the battery is full and the inverter is at max power the Quattro would raise the frequency and then the SolarEdge would throttle its output. This is an advertised service APS

Unfortunately and fortunately I tested the response to a raised frequency and it didn't work at all. So in the process of working out where to put the inverter I am looking at the dropped loads side of the Quattro. AC Out 2. In the event of a power cut, a relay is closed cutting off AC Out 2. I have my heat pump and car charger on this circuit. I was wondering what happens to the voltage etc if a circuit is cut off like that with inverter going at max power. Assume also the charger and heat pump are in idle mode. Is there a dangerous spike in voltage as there is no where for the power to go? Or is the shut off in these inverters so fast it isn't an issue? Thanks

edit-My thought logic would suggest it is a safe thing to do or it would be very easy to damage all the equipment in a house if the main breaker was shut off whilst exporting with low loads. But if anyone has anything to add that would be great. The other alternative would be on the AC IN side but I want to avoid that as there appears to be a flaw in the Victron Quattro which means that it is very slow to respond to load changes if there is anything connected on the input(grid) side.

[Andy]

I'm going to try an experiment later. I'll leave an old monitor plugged in and then turn off the main breaker and see what happens. Wish me luck. No sunshine at the moment.

[Andy]

To answer my own question it appears that a router I plugged in survived the experience. I couldn't find the monitor as I think it has gone to the recycling center already.

[Countrypaul]

Doesn't a router have a switched mode power supply to provide a stable DC voltage so wouldn't that help protect things? Something that runs directly off mains voltage such as an incandesant light bulb might not be quite so resilient.

[Andy]

Doesn't a router have a switched mode power supply to provide a stable DC voltage so wouldn't that help protect things? Something that runs directly off mains voltage such as an incandesant light bulb might not be quite so resilient.

It probably does. Unfortunately I don't have anything else to test it with. I have long since got rid of my old school bulbs. Also I only have a plain old multimeter so wouldn't be able to view the voltage spiking if it did.

[marshman]

Unless I have misunderstood your question, surely no grid connected inverter can or rather does generate damaging voltage spikes if they suddenly "lose the grid" unless the inverter is faulty.

[Andy]

Hi thanks Marshman. I think your situation is similar to mine. I think the equivalent way to think about my question is with very little load in the house just switching off the main breaker whilst at max export. If the inverter went and toasted everything at that point I think we would know about it. I was approaching this with an abundance of caution and paranoia.

[AlBargey]

What's the flaw in the Quattro that stops you using the AC in for the solar edge?

I have a Quattro, but only DC coupled solar.

From your threads on the Victron forum it looks like solar edge have faulty firmware, that hopefully you can get them to fix. If you can't and still want AC coupled, look at Fronius instead.

Opening the relays at full power on the Quattro shouldn't be a problem, they can be programmed to turn off and on under any load within specs, as many are used already. There's been a few threads there lately of people asking, and I think if you're really interested you can open it up and find the relay part number and check the specs, but it will be rated full load for hundreds of thousands of cycles.

[Andy]

What's the flaw in the Quattro that stops you using the AC in for the solar edge?

I have a Quattro, but only DC coupled solar.

From your threads on the Victron forum it looks like solar edge have faulty firmware, that hopefully you can get them to fix. If you can't and still want AC coupled, look at Fronius instead.

Hi. From reading the threads it would appear that if the Quattro is using an external grid meter then it is very slow to respond to load changes. If an inverter is placed on the AC In then a meter is required. It seems to be a combination of the meter being a bit slow and a 400w per second change limit set by the U.K. This leads to 15s for load changes to be equalised. If the Quattro is working on its own internal sensors then it seems to be ok. i don’t want to spend extra money rewiring to then annually spend quite a bit more on the extra importing and loss of energy.

Although it seems to have been working fine until now I am unfortunately tied in to the solar edge. The panels came with integrated optimisers which I didn’t realise was going to happen when I specced the system with my installer. I had assumed they would be external boxes.

[Caesium]

Hi. From reading the threads it would appear that if the Quattro is using an external grid meter then it is very slow to respond to load changes. If an inverter is placed on the AC In then a meter is required. It seems to be a combination of the meter being a bit slow and a 400w per second change limit set by the U.K. This leads to 15s for load changes to be equalised. If the Quattro is working on its own internal sensors then it seems to be ok. i don’t want to spend extra money rewiring to then annually spend quite a bit more on the extra importing and loss of energy.

I've read before that the Quattro/MP can react faster if its using a CT (a standard 100A/50mA model AIUI - wired into the current sense terminals) rather than an external meter (via RS485 I guess?). Have you tried this? Quite interested to hear the results if so, as I'm contemplating moving over to a Multiplus when my Luxpower inevitably gives up the ghost.