PV Inverter cutting off array sunny days

[Uklad]

I spent ages chasing missed generation on my unit a long time ago was down to high DNO voltage in peek generation times, you may need to keep an eye on the supply, if i remember correctly no error was generated when mine stopped generating I could only see the problem in the PVoutput records

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Find Something does not add up.. Advice and Help. How-to Something does not add up.. in the Solar PV Forum | Solar Panels Forum advice boards on ElectriciansForums.net Est.2006 | Free Electrical Advice Forum. Something does not add up.. on ElectriciansForums.net Electrical Advice Forum.

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[marconi]

Uklad: That is a helpful post because it is a line of investigation at the moment - thank you Sir.

Post automatically merged: Aug 28, 2020

RonanIrl: I have used these plug in meters for untrained folk to check supply voltage. I need to check further but I think they report max and min values too ie: of power, frequency or voltage.

Anyway it would be a safe way for you to monitor the supply voltage and they are not too expensive. All you'd need to do is plug it in and select the mode for frequency and voltage.

RS PRO Wattmeter-energy meter for plug mounting | RS Components - https://uk.rs-online.com/web/p/digital-power-meters/1785370?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Automation_%26_Control_Gear_Whoop-_-Digital+Power+Meters_Whoop-_-1785370&matchtype=&pla-603078136763&gclid=Cj0KCQjw1qL6BRCmARIsADV9JtaSbVu2XipejALeE4RsCxyEs6atjfiyN41AqBpwCgSTW9rEtkJDX7gaAskbEALw_wcB&gclsrc=aw.ds

Post automatically merged: Aug 28, 2020

I spent ages chasing missed generation on my unit a long time ago was down to high DNO voltage in peek generation times, you may need to keep an eye on the supply, if i remember correctly no error was generated when mine stopped generating I could only see the problem in the PVoutput records

Something does not add up.. | on ElectriciansForums

Find Something does not add up.. Advice and Help. How-to Something does not add up.. in the Solar PV Forum | Solar Panels Forum advice boards on ElectriciansForums.net Est.2006 | Free Electrical Advice Forum. Something does not add up.. on ElectriciansForums.net Electrical Advice Forum.

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Uklad: What inverter type do you have please?

Post automatically merged: Aug 28, 2020

Cable is long as inverter is one side of property and consumer unit other it also has to go up and over into attic space and back down so approx 15m.

What is the length of cable in the attic space please?

How hot does it get in the attic space on the problem sunny days?

Post automatically merged: Aug 28, 2020

Please look carefully at the white cable to the inverter which wends its way to the CU via the loft. Imprinted on it should be a figure in mm2 - what is it?

And what is the BS number?

 

[RonanIrl]

Thanks Marconi and UKLad I will order one Of the monitors and set it up.

Im on a few days holidays as of this morning so away from home but will be back with more info next weekend

will be back with BS standard of the cable I just missed it in the images I sent can only see BS EN but number is missing.

I have a solis 5kw hybrid inverter

The attic doesn’t get over 27 in summer and approx 12m of the 15m cable run through it.

Uklad: That is a helpful post because it is a line of investigation at the moment - thank you Sir.

Post automatically merged: Aug 28, 2020

RonanIrl: I have used these plug in meters for untrained folk to check supply voltage. I need to check further but I think they report max and min values too ie: of power, frequency or voltage.

Anyway it would be a safe way for you to monitor the supply voltage and they are not too expensive. All you'd need to do is plug it in and select the mode for frequency and voltage.

RS PRO Wattmeter-energy meter for plug mounting | RS Components - https://uk.rs-online.com/web/p/digital-power-meters/1785370?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Automation_%26_Control_Gear_Whoop-_-Digital+Power+Meters_Whoop-_-1785370&matchtype=&pla-603078136763&gclid=Cj0KCQjw1qL6BRCmARIsADV9JtaSbVu2XipejALeE4RsCxyEs6atjfiyN41AqBpwCgSTW9rEtkJDX7gaAskbEALw_wcB&gclsrc=aw.ds

Post automatically merged: Aug 28, 2020

Uklad: What inverter type do you have please?

Post automatically merged: Aug 28, 2020

Cable is long as inverter is one side of property and consumer unit other it also has to go up and over into attic space and back down so approx 15m.

.



What is the length of cable in the attic space please?

How hot does it get in the attic space on the problem sunny days?

Post automatically merged: Aug 28, 2020

Please look carefully at the white cable to the inverter which wends its way to the CU via the loft. Imprinted on it should be a figure in mm2 - what is it?

And what is the BS number?

 

[marconi]

This is the same meter but cheaper from Amazon - the ones I bought. When you look at the link you will see the monitor set to display the voltage and frequency. I have checked its functionality and it does not record max and min voltage only power. But it will serve the purpose of measuring your mains voltage safely.

View: https://smile.amazon.co.uk/Monitor-Backlight-Electricity-Consumption-Analyzer/dp/B085S7Q1T4/ref=sr_1_4_sspa?crid=IL03JRK08BUK&dchild=1&keywords=plug+in+energy+monitor&qid=1598772103&sprefix=plug+in+energy+%2Caps%2C-1&sr=8-4-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyQzU3Rjg0UTRQT0NNJmVuY3J5cHRlZElkPUEwMTAyNTgzMVhXVEpSM1VQUlFKVCZlbmNyeXB0ZWRBZElkPUEwNzU1NzEyM0swV09DNlhZTTNBNSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[RonanIrl]

Thanks Marconi I orders the one from RS should be in my house when I get home next week. does it log voltage or do I need to look at it when the issue occurs?

 

[marconi]

Alas, itdoes not log voltage over time so yes you will have the look at the reading when the problem occurs and for comparison at other times too.

 

[Uklad]

I have a Power One ( now ABB ) PVI-3.6-OUTD

 

[RonanIrl]

Hi guys so finally back form my holiday and the power logger was here.

Have been monitiorng it and it is reporting 235V...only fluctuates about =/- .2 either way. I know it will be most intersting to read it when the issue occurs next but thought this would be good info now as I dont think I will see the error until next summer due the weather and sun is now lower in the sky. (ony happens on sunny days in summer May-August)

Also managed to get the BS standard from the cable exiting the Inverter to the consumer unit is it BS EN 50525-5-11 300/500V. Is that Ok for a 15 mtr run carrying exported excess power thorugh my attic in 27-30 degress of heat?

Also having my electrician check the size of the cable running from my junction box to my consumer unit in case it is under spec'd ref the below thread i noted on an irish board, I want to know if I have 25mm sq cable or not.

Voltage drop in house - what to expect - https://www.boards.ie/vbulletin/showthread.php?t=2057837652 .

 

[marconi]

RonanIrl: Good morning. In the meantime you could check what I mentioned in #15 and ask the electrician to check the tightness and correctness of all the ac power connections between the inverter and the intake including where any mcbs/rcbos/rcds for the pv system are connected to busbars.

 

[marconi]

I am still thinking about your problem which I believe to be due to voltage rise of the network caused by other micro generation schemes (on very sunny days when export is high) near you on the distribution circuit you share with them, or volt drop along the cables between your inverter and the network, or a bit of both. Wilko and I have done some voltage drop estimates which we will come to later.

Meanwhile, to inform our analysis:
1. Is your home and those in the vicinity supplied by overhead or underground cables?
2. Can you see the transformer? If yes could you take a picture of it please?
3. Are you among those nearer to the transformer or those further away?
4. How many other pv schemes are in your immediate vicinity and what is their installed power - assume 250W a panel - so a four panel array would be 1kW.
5.Might you measure or re-check your estimate of the length of the 6mm2 cable from the inverter to the mains supply intake and re-consider how much of its length is in the loft (which is hot in summer).
6. If the supply is overhead - the classical 4 cables strung between poles - could you look carefully to see to which of the three upper cables is connected any local pv generation scheme. I wonder if by happenstance you are all or most of you are on the same phase cable - there are three phase cables and the lower one is the neutral.
7. A nudge again about answering my questions in #15.
8. I assume you are now taking some readings of home voltage during peak sun (ie midday) to discover any trends.

 

[marconi]

In London, so maybe too where you live it looks like we have some sunny days early next week so this could be an opportunity to do some voltage measurements.

 

[RonanIrl]

Marconi thanks.

See my comments below.

Voltage meter is in place has hadly fluctuated since install more or less stable bwteen 235-238Volts. Jumped to 238 when the run was out one day.

Today my installer said he is coming on friday next to replace the shunt as it may be faulty and cutting off above 70 degrees. Guess that could be the issue.

I am still thinking about your problem which I believe to be due to voltage rise of the network caused by other micro generation schemes (on very sunny days when export is high) near you on the distribution circuit you share with them, or volt drop along the cables between your inverter and the network, or a bit of both. Wilko and I have done some voltage drop estimates which we will come to later.

Meanwhile, to inform our analysis:
1. Is your home and those in the vicinity supplied by overhead or underground cables?
Underground cable from a mini box in an estate of only 5 houses.
2. Can you see the transformer? If yes could you take a picture of it please?
I can see the mini box not sure if it the trnsformer but its juts a steel box approx 100x100x50 cm with caustion high voltage sticker on it
3. Are you among those nearer to the transformer or those further away?
The box is only 7 meters from meters from my supply meter box on my wall.
4. How many other pv schemes are in your immediate vicinity and what is their installed power - assume 250W a panel - so a four panel array would be 1kW.
There is 4 houses just around the corner with 5 panels each for powering heat pumps etc (Irish build laws now require them on all new build houses to meet A rating) They were just built last summer and are now occupied. The direction they face is the same as my own roof. So 20 panels in total and they look like 250 panles where as mine are 350 panels.
5.Might you measure or re-check your estimate of the length of the 6mm2 cable from the inverter to the mains supply intake and re-consider how much of its length is in the loft (which is hot in summer). Its definitely 14-15 M in length measured form inverter to consumer unit last week and about 9 Meters run in the attic (remainder is drops up and down thruogh cavitys) where it get to approx 27 in summer.
6. If the supply is overhead - the classical 4 cables strung between poles - could you look carefully to see to which of the three upper cables is connected any local pv generation scheme. I wonder if by happenstance you are all or most of you are on the same phase cable - there are three phase cables and the lower one is the neutral.
Everything is underground in the estate it only runs overhead outside and its spagetti junction where it braches off unfortuantely impossible to follow a single line.
7. A nudge again about answering my questions in #15.
While the setting seems wrong i can 100% confirm that power is exporting when the Battery is full and the house is not drawing all the genertaed power. Im reluctant to change this setting but will ask the engineer next friday friday.
8. I assume you are now taking some readings of home voltage during peak sun (ie midday) to discover any trends.
As above see top off comments.
[/QUOTE]

Post automatically merged: Sep 11, 2020

Tends to only happen on super sunny summer days, doesnt happen at all in winter guess sun angle is also a factor here so it must be related to maxuimum generataion sustained from the panels causing the issue. I have 1.5 years of dongle data and it only happned in May - August 2020 on the sunniest warm days (system wsa only installed late August 2019 so missed summer 2019). Dont think it will happen agian until next summer when sun is at its optimum angle which seesm to be above 45 degrees which is interestng as the panels are at 45 degress on my roof (Pefect Perpendicular angle to the sun on the days it happens as i have a sun tracker app on my phone and the tiem of cut off is just as the sun goes aove 45 and sky is clear and weather very warm). Maybe it is this shunt they are coming to replace overheating.

 

[marconi]

The voltage drop Wilko and I estimated for the connection between your inverter and the main intake was between 2(me) to 3(Wilko) Volts at 21 Amps when you export 5kW. Wilko cleverly included the drops across isolators, mcb and at connections which explains his higher figure. As you are so close to the transformer I reckon any volt drop along the cabling between your home and it is of the order 0.5-1V (20 A x 0.05 Ohms = 1V).

In sum between your inverter ac output installation and the transformer a worse case volt rise of circa (nb 3 + 1 =4V) of 235 + 4 = 239V. Not troublesome if your supply voltage is circa 235V since the disconnect figures are typically 255V rolling 10 minutes (IIRC) time averaged, 260V peak for 1 sec and 261 peak immediate - and 239V < 255V.

What we don't yet know is the effect the other solar pv systems at peak sun have on elevating your incoming mains voltage so be be very interesting to find out.

I turned up this article which you might find interesting which helps to explain our line of thinking on your peak sun disconnect problem. For example you will read about the cable between the inverter and the mains intake and the suggestion to double up on it if the run is long - hence our volt drop estimates - to see if this might make a difference. It also explains inverter cycling at high voltage rise. Wilko and I don't understand why there is no fault code reported by your inverter which tends to indicate this is not happening in you case unless the internal logic is that this is not a fault per se but rather an event - I recognise this is semantic thinking. Let us hope for some sunny days next week.

Solar Voltage Rise - why you should care | MC Electrical - https://www.mcelectrical.com.au/solar-voltage-rise-explained/

 

[marconi]

Me again

In #1 you said you had 315W panels yet above you wrote 350W - could you confirm which one please?

Also could you give me the details of a panel too so I can look up its specification please?

 

[RonanIrl]

sorry they are 315W Q peak duo black G5 panels

https://www.q-cells.com/dam/jcr:1402ddc6-d3de-4e13-aa7a-74aa008e117a/Hanwha_Q_CELLS_Data_sheet_Q.PEAK_DUO_BLK-G5_300-320_2018-03_Rev02_NA.pdf

Me again

In #1 you said you had 315W panels yet above you wrote 350W - could you confirm which one please?

Also could you give me the details of a panel too so I can look up its specification please?

Post automatically merged: Sep 12, 2020

very interesting article I did note a slight voltage increase on the grid last week on a sunny day it was up at 238-240 (normally 235 stable) but the location of other solar installations nearby are minimal as noted above. When the engineer is here next week I’m going to ask him to also check the size of the cables from consumer unit to meter and meter to transformer if possible and let you know the size and length.

The voltage drop Wilko and I estimated for the connection between your inverter and the main intake was between 2(me) to 3(Wilko) Volts at 21 Amps when you export 5kW. Wilko cleverly included the drops across isolators, mcb and at connections which explains his higher figure. As you are so close to the transformer I reckon any volt drop along the cabling between your home and it is of the order 0.5-1V (20 A x 0.05 Ohms = 1V).

In sum between your inverter ac output installation and the transformer a worse case volt rise of circa (nb 3 + 1 =4V) of 235 + 4 = 239V. Not troublesome if your supply voltage is circa 235V since the disconnect figures are typically 255V rolling 10 minutes (IIRC) time averaged, 260V peak for 1 sec and 261 peak immediate - and 239V < 255V.

What we don't yet know is the effect the other solar pv systems at peak sun have on elevating your incoming mains voltage so be be very interesting to find out.

I turned up this article which you might find interesting which helps to explain our line of thinking on your peak sun disconnect problem. For example you will read about the cable between the inverter and the mains intake and the suggestion to double up on it if the run is long - hence our volt drop estimates - to see if this might make a difference. It also explains inverter cycling at high voltage rise. Wilko and I don't understand why there is no fault code reported by your inverter which tends to indicate this is not happening in you case unless the internal logic is that this is not a fault per se but rather an event - I recognise this is semantic thinking. Let us hope for some sunny days next week.

Solar Voltage Rise - why you should care | MC Electrical - https://www.mcelectrical.com.au/solar-voltage-rise-explained/