Spoke too soon!!

[richbee]

Having read the initial comments about the CT clamp, I notice that the inverter manual mentions that the CT lead can be extended by up to 10m.
I reckon this one must be about 10m from the meter, if not more, as it is in the loft.
Could this be part of the problem?

[Oldgreybeard]

Unlikely to be a problem, the CT from our grid supply to the inverter is way over 10m and it works just fine. The signal is not really affected by the cable length to any great degree so I doubt this is the cause of the problem.

Does your inverter have a set up procedure for the CT? The Sofar has a bizarre requirement whereby there has to be a significant load (a kW or so)on in the house and the PV system must be turned off, or not generating, when it is first powered on. It then sets the grid CT up based on this load. Unless you then go into the depths of the main menu and "freeze" the CT setting it will need to do this every time it is powered on, which can be a PITA. There's nothing much in the manual about this process, I ended up finding it out via a social media post.

If your inverter has a similar setup process it may be that it's somehow got the impression that there isn't a CT connected. The symptoms you've got are indicative of a missing grid CT I'm sure.

[pudding]

I've not got the manual in front of me but from memory of a few posts i remember seeing, I think there is a ratio value you can set for the CT clamp you use, if different from the default one supplied. I'm planning on extending the supplied CT clamp to 15m or so using CAT 6, and I believe as long as it doesn't run near other power cables to pick up interference should be fine.

I'll take a look at your pics and the manual soon and see if anything jumps out at me as being not quite right from what I've read and watched, but as I say I've not even got my inverter yet so definitely no expert.

[richbee]

Thanks guys - really appreciate the input.
I've now got in touch with one of the technical guys from the installation company, so they are looking at it......we'll see.

1 good thing I've found is that you can access all the inverter settings from the app - so I don't have to go climbing into the loft every time I want to check or change settings

[pudding]

Have you got a separate connection to the inverter for essential loads in case of a power cut? If not, uncheck that limit to load only box, as at the moment I think on system2 settings page, this means you're not outputting back to the grid connection on the inverter (which is the normal connection to the whole house and consumer unit too).

Also, have you got anything connected to the Gen input on the inverter (wind turbnie/other generator)? If not I dont think you need any of those Gen settings ticked as they dont do anything.

[richbee]

Right, I can try those - I wasn't sure what they all meant - was just trying to stop the grid + PV charging the battery yesterday when it first started.

Just had a not terribly helpful call with a 'technical' guy - who thinks everything is running fine - despite a whole 3 bed house running fridges / freezers / lights / PCs / stereo / smart devices on continuous 20W!

Also not sure if I'm being thick, he kept trying to tell me I wanted the system on 'Battery priority' instead of 'Load priority' - But unless I've misunderstood, you want the PV to run the load and charge the battery with spare capacity - if you prioritise the battery, the grid runs the load, which is just stupid??

[pudding]

Yeah, def load priority. Think that's advice more for where you have flaky mains supply so want the batteries charged max all the time, which is for the main market in South Africa.

[richbee]

Brilliant, thanks Pudding

[richbee]

Unlikely to be a problem, the CT from our grid supply to the inverter is way over 10m and it works just fine. The signal is not really affected by the cable length to any great degree so I doubt this is the cause of the problem.

Does your inverter have a set up procedure for the CT? The Sofar has a bizarre requirement whereby there has to be a significant load (a kW or so)on in the house and the PV system must be turned off, or not generating, when it is first powered on. It then sets the grid CT up based on this load. Unless you then go into the depths of the main menu and "freeze" the CT setting it will need to do this every time it is powered on, which can be a PITA. There's nothing much in the manual about this process, I ended up finding it out via a social media post.

If your inverter has a similar setup process it may be that it's somehow got the impression that there isn't a CT connected. The symptoms you've got are indicative of a missing grid CT I'm sure.

That makes sense, otherwise how can a simple CT clamp on the incoming detect the balance between load, PV, grid and battery.

They have tinkered with the settings and the 'load' now follows the PV output - so nothing overnight, and now up to 800W, once the battery finished charging. It claims I have imported 0 from the grid, but the meter tells a different story!

[pudding]

Dont think the CT clamp has to detect any balance per se, simply if there is export to the grid and the flow direction. Such that if power is flowing back to the grid, the inverter will take that and redirect it to the battery until the export is zero again. The 'balance' is simply whatever is left after PV generation-load=grid import/export.