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Grid power voltage too high???


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I have just commissioned a grid-linked direct inverter solution at my offices (photos posted a week or two back in the gallery). The panels produce up to 9 and a bit Kwh in full sun. They are arranged in 4 strings, two pairs of strings feeding two separate direct inverters (2 X Solis/Kodak branded 4.6Kw) and then feed into a grid connection. In the last week I have noticed one inverter dropping out and giving an error message that the resistance on the AC is too high. The inverter immediately cycles and picks itself up again, but this happens several times in a row during the high sun part of the day.

The two inverters are set up the same and the only difference between them is the length of the AC output cable to the AC DB, but the difference is less than 500mm (the inverter with the slightly longer AC cable is the one dropping out). I don't think this can make a substantial difference, but maybe it is enough to tip it over???

The other thing I notice is that during these high sun/high production periods the grid voltage is reading at 250V and just over. That seems abnormally high, and I wonder if the inverter is not taking strain having to match this voltage?

I have just measured the voltage at the Mains DB as 238.1V, and the inverters are also stating 238.1V, so it looks as if they are reading the same voltage.

I shall keep an eye on this today, but would appreciate any wisdom from the group.

The wiring to the solar DB is incomplete because reasons.


solar pergola #3.jpeg

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6 minutes ago, PaulinNorthcliff said:

that the resistance on the AC is too high

Might be a loose connection. 

6 minutes ago, PaulinNorthcliff said:

but the difference is less than 500mm (the inverter with the slightly longer AC cable is the one dropping out)

From a Victron perspective. Not sure what the effect on your inverter will be, But believe me, this does make a huge difference. 



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8 hours ago, PaulinNorthcliff said:

I'm unsure of what to make of most of your reply. Remember I'm really stupid, so words of one syllable are in order.

In short, lets say you use a nice size cable to connect two inverters in parallel (Not 100% your situation) anf the one has a longer cable than the other, the one with the shorter cable might end up doing more work than the one with the one with the longer cable due to resistance differences as well as voltage monitoring.  

I feel that in your case it might not be the reason for your issues as the grid tie inverters is not paralleled the same way as the battery inverters, but its good engineering practice to keep those wires as symmetrical as possible. 

I still feel the issue might be a loose/Bad connection or bad crimp or something similar on the AC side. 


8 hours ago, PaulinNorthcliff said:

BTW, I have yet to be invoiced for the inverters so I still can't tell you what they cost ;-{>}

Not a problem..

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3 hours ago, Fuenkli said:

how do you use 52.6kWh's / day 🤣

A lot of coffee and a couple of very long showers might help......

Edit: Joke you not, I am currently looking at a possible solution for a client with an average night time usage of  122kwh from 16H00 till 7H00 the next morning measured over 7 days. This is on a Single Phase supply to 3 Bedroom home with 2 Occupants. 

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22 minutes ago, PaulinNorthcliff said:

Let's just say I'm a very generous and patriotic soul and I believe in sharing.


Sounds like me watering the next door guys garden with my wellpoint and solar while they on holliday . Hehehehe

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