question

andy156 avatar image
andy156 asked

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
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
Jason - UK avatar image
Jason - UK answered ·

@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?

6 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

andy156 avatar image andy156 commented ·

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.

0 Likes 0 ·
Show more comments
andy156 avatar image
andy156 answered ·

*** 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.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

andy156 avatar image
andy156 answered · 
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


2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.