Hoymiles problem, or grid voltage too high?

[pudding]

I've got exactly the same issue, so I'm glad its not just me and my Hoymiles that's been behaving like this.

I've got a few devices that can measure the grid voltage, closest to the grid is a Shelly inside the consumer unit measuring the GSHP circuit. Here's a screenshot from today, grid power at the top showing spiky exports from the passing clouds. Then the middle chart shows 4 devices and their voltage measurements, with red being the highest of the measurements from the GSHP Shelly device inside the consumer unit, and bottom chart is the Hoymiles output, where you can see it dropped to 0 twice today. When it drops out, it seems the highest grid voltage from the Shelly in the consumer unit peaks at 256V, the Shelly connected to the Hoymiles doing the same measures about 253V in yellow, and this seems to be enough to shut down the Hoymiles for 20mins or so until it comes back up.

[Ken]

Are we sure the hoymiles should switch off at 253V. Why would it not have a small plus tolerance as they know its going to increase the voltage.

If the grid voltage is within spec and then inside the house you are increasing the volts above spec then surely there is only one person to blame.

In my ignorance i thought all inverters etc had a + tolerance above 253V , mine does.

Also be careful what you wish for as you might end up with too low volts in winter. In my case they just tapped into a different phase of the 3ph in the road outside.

[Joeboy]

Our Hoymiles 1000 2T cuts out for about 30 minutes in the middle of the day. I haven't monitored to see what V it trips at but i'm confident its above 253V.

This from the web
"Hoymiles microinverters have a grid overvoltage cutoff, meaning they will shut down to protect themselves and the grid if the voltage becomes too high. The specific cutoff point varies depending on the Hoymiles model and the applicable grid standard, but generally, Hoymiles microinverters will shut down at around 262.2V for 1 second or 273.7V for 0.5 seconds."

Anecdotal, Our Enphase units which are all single panel micro inverters have never tripped.

I guess its just the price we pay for having so much RE on the grid?

[richbee]

My hoymiles trips out at exactly 253.
It's been off most of the day, from 10:30 ish
Always worse once the batteries are full and it's exporting.

It might even be worse this year, now that one of the neighbours also has solar (there's 5 houses on the end of a powerline, so nowhere for the extra to go)

[AGT]

Could you introduce volt drop anywhere?

[pudding]

Same for me yesterday, the Hoymiles tripped off 3 times, seen bottom left of the graphs, each times a cloud passed and spiked the voltage, so missed a few kWh of generation at peaks times



During the night we were charging the car and batteries so pulling in 12kW, and the voltages in the house didn't drop below 230V, so would it be safe to induce a voltage drop somehow like you mention @AGT ? How so?

[Fueltheburn]

Yesterday was a stonking day for Solar in Aberdeenshire.
Before I saw this post, I was looking at the production curve on my Hoymiles and I think it is the cleanest I have ever seen it. It had virtually no dips in the rise and fall.

HMS 800 on 2 x 405W Canadian Solar panels.


Anyone running a voltage stabiliser to reduce the grid voltage down to about 222 - 225V? I had one but never fitted it.

I also wonder if you run your entire mains through a victron inverter, does this unit stabilise the grid connection? It seems to have a massive Toroid in it.

[robl]

A voltage stabiliser (optimiser) could drop your home voltage a bit, though the actual grid voltage at your mains fuse would still be just as high (or higher). Can you tweek the hoymiles, up the trip level a bit - it would have pretty much the same effect. Our sunsynk regularly reports over 253V, it’s never yet tripped out - piccy happily exporting 6kW at that voltage peak below, importing 8kW in the dip.

[AGT]

You could change circuit design with a maximum voltage drop of 3% for distribution circuits supplying fixed equipment like inverters, and make it slightly higher, either longer cable run of course this is for us self installers not for those getting a MCS /electrician in…

Just a thought

[Marcus]

I don't know anything about hoymiles, so I don't know if you have access to its settings. If you can set it to a UK spec it ought to keep working up to 264v ish. That would be the optimum solution.

You can get voltage optimisers that reduce the supply voltage to your house, though I'm not convinced they would save you any money as they claim. This one seems to be an autotransformer that reduces the voltage by 7.5% (~18v):-

https://www.cef.co.uk/catalogue/product ... ation-unit

If I were considering this solution myself I'd probably cobble up something similar, but just for the hoymiles, not the whole house, which would be much cheaper:

E.g. if you were just going slightly over 253v with an inverter that could output up to 15A a.c., then knocking off 10v would suffice, so I would look for something like a 150va 10v: 230v, (I.e. 15A at 10v output) transformer. Connect the 10v winding in series with the 230v winding to make a 230/240v autotransformer. Check you've got the polarity right by connecting 230v to the 230v 'tapping', and the output from the ends should be 10v more, not 10v less. Connect the '240v' to the grid side and the hoymiles to the 230v tapping, and the hoymiles should see grid -10v, approximately.

If the output of the hoymiles is approaching 253v the output from the autotransformer will be near 264v though, which is still OK, but it is the reason I suggest a 10v transformer: a 20v transformer would get the apparent voltage at the hoymiles nearer to 230v at grid=250v, but then the hoymiles wouldn't cut out until the grid reached 253+20v, which would be inadvisable.