Dealing with excess solar:

[richbee]

I deal with excess solar by,

1) Home battery becomes near full and the DC coupled charge controllers will simply throttle off and shut down.

2) First 4kW excess gets exported, any more excess gets diverted to pump power into storage heaters and/or hot water tank.

3) If I’m out, any further excess gets exported up to 5kW, thereafter the SMA Sunny Manager throttles the grid tie inverters to keep at a constant 5kW export plus whatever the house is using.

4) If I’m in, then its preferable to prevent the home battery getting too full to keep the DC charge controllers in business. On crazy summer days there can be 10kW or 12kW coming in so I turn on the EV chargers and set them to whatever allows max export. I also look ahead at the forecasts, so if it looks really good, I might need to dump some of the home battery stack to the grid overnight to allow empty space in the home battery the next day and I turn the charge rate down to allow the max export early in the day.

With the obscure higher export rebates compared with cheap rate import, I no longer worry about a low home or EV battery at the end of the solar day as it’s cheaper to import overnight and export as much during the day.

Interesting idea - export at night to drain the battery in anticipation of a good solar day ahead......
Not sure the Sunsynk can export to a schedule - it's just on or off

[richbee]

I have this problem with my extra Hoymiles PV - where the voltage goes above 253 during exporting and it trips out.
...
It still tripped out most days over the past couple of weeks - but in most cases not for too long.
It's frustrating

I too am quite close to the limit. Fortunately I reused an old 6 sq mm shower cable to my loft so it is quite low resistance. Is there anything you can do to reduce any voltage drops between the inverter and the incoming connection?

If you are within the export current limit agreed with your DNO surely it is their problem to ensure that the voltage at their supply head does not exceed the 230 + 10% statutory limit? Have you spoken to them?

I had the DNO out to look at the high voltage, which was, of course, lower than limit at 251V at the time. I did mention that as I had DNO authorisation to export 3.8kW, that they should make sure I was able to do that - but he didn't seem impressed and mentioned that it was my inverters 'fault' that the voltage was over limit

[richbee]

I have this problem with my extra Hoymiles PV - where the voltage goes above 253 during exporting and it trips out.
I have reduced the charge current for the batteries to try and spread out the charging time, but at the moment, the battery doesn't discharge that much overnight, so can only help a little bit.
I've also capped the export at 3.4kW in the Sunsynk system with CT coil, rather than the maximum setting of 3.9kW, in the hope of reducing the peak voltage during sunny days.
It still tripped out most days over the past couple of weeks - but in most cases not for too long.
It's frustrating

Microinverter issue: If the problem is isolated to a single panel, it could be a faulty microinverter ?

I have it running as a dumb inverter currently, so I can't look at the individual panel outputs, but it only ever trips out when the grid voltage is high, I've seen it reach 253 and instantaneously trip out (measured by a separate energy monitor in the circuit)

[sharpener]

I had the DNO out to look at the high voltage, which was, of course, lower than limit at 251V at the time. I did mention that as I had DNO authorisation to export 3.8kW, that they should make sure I was able to do that - but he didn't seem impressed and mentioned that it was my inverters 'fault' that the voltage was over limit

That's not very helpful of them! Do you know if it measures the same in your meter cupboard as it is at the inverter?

It's getting worse here, last night well after dark (so no PV!) the system voltage was above my 250V warning limit on two occasions and emailed me to say so. There seems to be a pattern whereby the voltage zig-zags down over an hour or two and then jumps up again, I wonder if this is a big local load switching off or an auto tap-changer trying to keep up with the load profile, it seems particularly bad in the evening peak around 5 p.m. (see pic).

And even as I have been writing this it has gone above 250V again even though I am only generating 1500W. I think I will have to reset the threshold to 251V now, it does not seem to have any deleterious effects save shortening the life of my few remaining incandescent light bulbs.

[Mart]

I have this problem with my extra Hoymiles PV - where the voltage goes above 253 during exporting and it trips out.
...
It still tripped out most days over the past couple of weeks - but in most cases not for too long.
It's frustrating

I too am quite close to the limit. Fortunately I reused an old 6 sq mm shower cable to my loft so it is quite low resistance. Is there anything you can do to reduce any voltage drops between the inverter and the incoming connection?

If you are within the export current limit agreed with your DNO surely it is their problem to ensure that the voltage at their supply head does not exceed the 230 + 10% statutory limit? Have you spoken to them?

I had the DNO out to look at the high voltage, which was, of course, lower than limit at 251V at the time. I did mention that as I had DNO authorisation to export 3.8kW, that they should make sure I was able to do that - but he didn't seem impressed and mentioned that it was my inverters 'fault' that the voltage was over limit

Hi, I forget where the actual legislation can be found, but the DNO's have to maintain the voltage within -6% / +10% of 230V (216V to 253V) even if there are SSEG's (small scale electricity generators) on the network. So it is their job.

I had a good argument with a guy who worked at a DNO, slagging off PV on the MSE PV threads. This was a decade ago. He said that since demand side PV started rolling out, the number of over 253V issues had gone up tenfold. He blamed the PV. I pointed out that it's their job to manage this, and that I doubted the number of incidents had gone up tenfold, it was simply that folk with inverters switching off, that were highlighting the problems ....... that the DNO's hadn't been managing, and potentially damaging some electrical goods in folks houses. [I think many electrical items can now vary amps, to manage watts now, but I may be making this up. Would love to know more.]

[sharpener]

[I think many electrical items can now vary amps, to manage watts now, but I may be making this up. Would love to know more.]

Yes, anything with an electronic power supply (including probably LED light bulbs) will achieve a constant output voltage on the load side and hence constant power demand. So (assuming unchanged efficiency) as the supply volts go up the current drawn will go down.

Doesn't apply to resistive heating elements though so things like toasters, dishwashers and washing mc/s will all run hotter and wear out faster. A side consequence of unification is that washing mc/s used to be rated at 3kW @240V being the max a 13A skt could supply, now they seem to be rated at 2.2kW @230V but the reality is of course that means 2.6kW at 250.