Exporting 12kW results in voltage over 253V

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andy156 asked May 24, '23

Exporting 12kW results in voltage over 253V

My new Quattro system in the UK has an agreed export limit of 13kW. However, today with sunshine and wind in the area the voltage went close to 260V as measured on the AC IN before I intervened. I was exporting close to the 13kW when this happened. I reduced the export limit to what I had with my previous 5kW inverter. This lowered the voltage below 250V.

Looking at the UK grid codes, it seems that no action is taken by the inverter until 262.2V is reached. These figures seem high given the voltage should be no more than 253V and I can't believe it is doing equipment at home any good. May be I am wrong.

I'm going to write a some code that will be monitoring the voltage and vary the max feed in to keep the voltages below 250V. Is there some other way of doing this more easily in settings or is it even necessary for me to do?

MultiPlus Quattro Inverter Charger

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Jason - UK answered · May 24, 2023 at 10:58 PM

@Andy156, if the voltage goes above 253, then you can submit a request to the network operation in your area. I had the same issue all year. Contacted SSE and they moved the tapping's on the local sub station for me to step the voltage down from 248/253.2v down to 240/245v (min/max) as were I live, there are many houses with PV so because of that, the voltage shoots up during the day casing my grid tied PV inverter to shutdown on over-voltage. If you have your system set up correctly with the correct grid code, your PV inverter or Multiplus/Quattro should not be generating above 253v to comply with the G99 requirements set up within your DNO application. Both my Multiplus and grid tied PV inverter shut down at 253v which is what any type test approved inverter should do if the voltage goes above 253v. Is your DNO application for your PV system or for your Quattro?

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andy156 commented · May 25, 2023 at 08:46 AM

Thanks. I had the problem of my original SolarEdge pushing the voltage too high as well and did exactly as you described with regards getting the transformer retapped. It was cutting out at 253V. It actually had to be replaced completely as they were unable to retap the old one.

Strangely neither the Quattro nor the Solar Edge cut out this time. I wasn't at home so could only see that the voltage was high on the VRM. I have had the SolarEdge updated and it was the same 262.2V figure now which seems to be the G99 amendment 8 figure g99 amendment 8 link. I can't actually request a retap of the transformer as to bring the voltage down any more will mean the voltage is too low at night. I'm dancing in the middle so to speak. 13kW export and 60 amp night time load doesn't leave a lot of wriggle room.

Does anyone know why the limit is now 262.2V and not 253V. It seems to have changed between G59/2 and G59/3. Has this been worked out to be necessary and ok due to the large number of solar pv installations? 260V just feels a bit excessive with regards to the life time of other equipment in the house. At least for me i don't get paid at the moment for anything I export so i can limit the export for now. I was exporting the maximum in order to get a true reflection of what i could generate in the year so I can then calculate whether any more batteries would be useful. Also it is good to just give back renewable energy.

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Jason - UK andy156 commented · May 25, 2023 at 10:40 AM

@Andy156 G59 doesn't exist any longer. The Quattro should have been installed and commissioned to G99 and your PV installation to G98/G99. Is the over voltage from your equipment of the grid?

If the over voltage is from the grid, over 253, then the supply voltage is outside their requirements which is classed as an emergency situation which they have to act on.
If the over voltage is due to your generating equipment, then the system can go upto 262v under G99. Below are the type test requirements for the Quattro
As you'll see, current equipment does not have to start shutting down until 262.2v within a second. If like me, you'll find anything above 250v in the house, things start to fail. My oven element went pop on me not too long ago and my Henry vacuum also failed because most electrical equipment sold is rated at between 230v to 250v, some even rated upto a maximum 240v so I really dont want a voltage above 250v in my house.

Is this a self install? I'm wondering why you are not getting paid for your export, I'm guessing no MCS installation.

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andy156 Jason - UK commented · May 25, 2023 at 10:57 AM

Hi,

That's essentially what I said in the previous comment. It's commissioned to G99 but I noticed the different behaviour to my first inverter installed on a G59 (it has since been updated to G99). I find it odd that the G99 lets the voltage go so high due to generation in the house when a lot of electrical equipment is so sensitive to it. Anyways, I've fixed the problem but might lower the max voltage to 250 based on what you have mentioned about your failures.

I don't get paid for my export from SEG as I get more money from my old FIT. I can't get a smart meter due to a 'remote location' and most SEG payments that are any good are predicated on having a smart meter. For example UW will only give 2p/kWh under SEG. I get around 5p from memory for my deemed export from the previous install.

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andy156 Jason - UK commented · May 25, 2023 at 11:52 AM

@Jason - UK I'm slightly confused between your first comment and last comment. If the first you say your inverter shuts down if the voltage is over 253V but then in your second you say it can go to 262.2V if self generating. But you also say the generators mustn't go above 253V if generating.

262.2V seems to be the 230V+10% +4% for internal rise in the generator and metering error.

Do you mean it will shut down if it detects the grid is at 253V with no PV generation? The over voltage is 262.2V which used to be defined as 253V in the old G58/2. Are your devices set up for the old standard if they are limiting at 253V?

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Jason - UK Jason - UK commented · May 25, 2023 at 12:31 PM

@Andy156 Apologies, at 262.2v the inverter has to shut down within 1 second under G99. The system should be designed to operate at a maximum of 253v but its doesn't have to stop inverting in ESS if you have to export above 253v. Generally inverters will start to throttle back on the generation when going above 253v as not to go above 262.2v to meet the type test standard. My PV inverter stops at 253v whereas my Multiplus still works above 253v but reduced output so you are right, my PV inverter must be set to the old standard even though it was installed 2 years ago.

The issues i was having is that I was missing out on export earning because my PV inverter kept shutting down at 253v whereas I could still discharge my battery on to the grid.

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andy156 Jason - UK commented · May 25, 2023 at 02:16 PM

It's a frustrating business. When I had the installation done in the winter I could export the 13kW and easily stayed within 253V. The early summer months are the hardest to deal with.

For me I only earn money on the original install so I can set 5000kW as the max export and just let the SolarEdge do its thing with the Victron throttling.

One reason I chose the victron was the ability to code round issues with my mixed setup. Obviously not an easy thing to do for most people but it gives great flexibility. Below is the nicely capped voltage. With the export limit set to 13kW it would be closer to 256V right now. Maybe a Victron setting allowing a maximum voltage (below the G99 standard) would be handy if you want to avoid over-volting equipment at home.

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Modifications Space

Node Red Space

Answer 1 · 2023-05-25T10:37:21Z

andy156 answered · May 25, 2023 at 10:37 AM

*** There is a better solution in the next answer ****

I have a node with inputs coming from the grid and voltage.

msg5.payload =clampValue((252 - voltageIn) * 800 - grid,0,13000)

Msg5 is an output going to the ESS max feed in value node.

The clamp value makes sure the result is in the range 0 - 13000 for the feed in. It is just a max/min function.

This simple function keeps the voltage from the Quattro below 253V which is hopefully extends the life of my household equipment some what.

You might need to fiddle with the value of 800 to stop it hunting too much. I really should have an average over the last 20 seconds or so as changing the ESS max feed in value doesn't have an instant response. This is good enough as a start point.

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Answer 2 · 2023-05-25T12:38:03Z

andy156 answered · May 25, 2023 at 12:38 PM

var feedIn = context.get("feedIn")
var vDiff = 250-voltageIn
var gridDiff=feedIn+grid
var correction =0

if (vDiff<0) {
    // Greater than the voltage we want. make a big correction
    feedIn=feedIn+vDiff*800
} else if (vDiff>.55 && gridDiff<500 ) //.55 stops continued hunting due to viltron discrete steps of 100watts on feed in.
{
    // Creep up on the export figure from below. Can go faster at the start.
    correction=(30 *Math.pow(vDiff,2))
    feedIn=feedIn+correction
}
//node.warn(feedIn+":"+vDiff+":"+gridDiff+"c:"+correction)
feedIn = clampValue(feedIn, 0, 13000)
context.set("feedIn",feedIn)
msg5.payload=feedIn

This code is better as it is more stable for the ESS algorithm. It makes a big change if over voltage but otherwise more slowly increases the export until within .5 volts of the required maximum. In this case I am using 250V.

In node OnStart you will need to set your initial export figure.

context.set("feedIn",5000) // Initial allowed export of 5000

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