Electricity Grid Com Fail

Electricity Grid Com Fail notifications started when the system was first switched on ( 18July).
The original configuration was 2 x ( 3kw inverter with 8.2kw batteries).
Faults reported on portal and via installer.
After 4 days of continually charging and discharging to the grid the installtion was switched off.

On 1st Aug the installer reconfigured the system to be 3kw and 2 batteries.
The inverters where swapped over as well to test.
GE said I would need a site visit.

Photos of clamps sent to GE who said they looked ok.

Still got the Electric Meter Com Fail.

The notification is regular 7min cycle.
Ie
Alarm raised - 10.49
Alarm cleared - 10.51
Alarm raised - 10.56
Repeat until switched off.

Any ideas on how to resolve this whilst waiting for GE to confirm site visit.

Check the data cable between EM115 meter and inverter is twisted pair and using an actual pair.

Seen so many now with issues, one had this data link with 2 core 0.75mm lighting cable, but black.
Needless to say, didnt work well

How long is the cable? Apparently Owen Brothers (makers of the meters) recommend that a 120Ohm terminating resistor is used at the inverter/battery end for lengths over 25metres.

Hi
CT cable cables are as supplied
Cable from em115 to inverter is about 2m

TheDragon (GivEnergy)

The original cable was screen network cable.
GE asked for it to be replaced. Installer said only had 1m 3core. They said that was ok.

Same fault on both cables

mrand31

Hi
CT cable cables are as supplied
Cable from em115 to inverter is about 2m

Is the polarity correct both ends? + to +

On the twisted pair. Is it using 1 pair? Eg blue, or orange, or green, or brown.

TheDragon (GivEnergy)
At the moment it is 3 core 1mm white mains cable. GE requested the original cable be replaced.

It sounds like your installer has never got the EM115 electric meter correctly communicating with the inverter.

Was the original design to have 1 x EM115 connected to 2 x 3kW AC-Coupled inverters?

It could be a faulty EM115 meter, wrong Modbus device ID number programmed in the meter (should be ID=1), or a faulty connection (as they are polarity sensitive, +ve to +ve and -ve to -ve).

Note - When multiple EM115 meters are daisy chain connected on the same network they each need to be programmed with a unique ID number. With an AC-coupled inverter, ID1 is used for the grid meter, and ID2 and ID3 can be used to monitor existing solar PV inverter outputs such as those with a FIT that cannot be modified.
Your installer may have got an EM115 meter with ID=2 or ID=3, which will not be seen as the grid meter even if the cable connections are correct.

The correct cable type for Modbus RTU comms is a screened single twisted pair with specific impedance characteristics, but for short distances using 1 twisted pair from within a CAT5 or CAT6 cable will usually suffice.

With a two metre cable length at 9600 Baud, any cable at all will do the job perfectly well.
Assuming it's not a gen2 inverter (don't know about them, might be different), the modbus connection should be in the one on the right hand side that doesnt say CT. The positive wire should be on the side marked with a '+'. Once you've got the cover off, it's easiest to see if you've got a torch and are limber enough to look upwards at it. The EM115 has the modbus connections marked as + and - as well and the wiring to that probably ought to be checked.

Simon_C
Hi
Original config was 2 * 3kw inverters.
Lots of issues - daily random complete discharge / charge cycles.
Agreed with installer to move to 1 inverter and 2 batteries in interim to see if that would resolve some issues. It didn’t.

Em115 Id 1 - CT to grid - em115 showing correct ( expected values).
Em115 Id 2 - CT to Solar ( showing expected values - verified against immersion mk1 and sma portal).
IDs checked.
Baud speed 9k6

Both em115 daisy chained to inverter via 1mm 3 core white mains cable as GE asked installer to replace cable. GE said mains cable was ok ( 2m cable run)

Solar peaks at about 5kW on GE app/cloud when inverter is 3.6kw and sma portal shows max at 3.5kW.

Mike407
Non twisted cable with suffer interference from the mains cable running next to it.

I would not use anything other than cat5e or above.
Regardless of distance. Especially if it's in the same trunk as the mains or in the Cunsumer unit, loads of noise.

Thanks

Installer coming back next Friday with a selection a parts to try and resolve issue.
Will update once they have finished.

TheDragon (GivEnergy) Non twisted cable with suffer interference from the mains cable running next to it.

I would not use anything other than cat5e or above.
Regardless of distance. Especially if it's in the same trunk as the mains or in the Cunsumer unit, loads of noise.

Sorry, but with 2m of cable you'd need to be welding right next to the cable to have any effect on RS485.

Sorry forgot to update.
Installer replaced em115 ( id01) and cable.
System has been working fine with no commas errors.
(Until last night when the system dumped its charge and only charged to 46% and is not charging or discharging - separate thread)