I have the Kodak OG-7.2 inverter, 4360W PV panels, and recently had a second Freedom Won 5 kW e-Tower battery installed to make a total of 10kW Batt power now.

On 13 July 2023 we had a proper '"Brown out" in Montagu when power was trying to restore after a 4 hour loadshedding episode, with power reading from 90 to 110V for about 32 minutes (according to the alarm report from my neighbour).

My concern is that my Inverter didn't know what to do, as the lights was dimmed and then finally the TV switched off - only the 4W leds stayed on. The Inverter switced over (on and off) a few times and settled on City Power AC (90-110V)  instead of staying in Batt-mode - it was in SUB mode.  I realised something was wrong and manually switched off Eskom (mains trip) and set the Inverter to Batt mode (SBU) where all was fine. I saw the street lights was also dimmed and eventually was shut down until Eskom was repaired. I stayed on SBU mode until the next morning because I didn't trust Eskom when I go to sleep. My power consumption was only about 750W during the loadshedding before the switch-over attempt.

According to my inverter Setting-03 the AC input default was set on "Appliances" which is 90-280V. Surely the Inverter was supposed to not switch back to Line-Mode unless it can add power from the battery and give me an output of say 230V (there was at least 60% batt power available). It did report a "Warning Indicator 10!" on the display (Output power derating) but I was just focused on getting Eskom killed so didn't count beeps or anything else.

My interim solution was to change the Setting-03 to "UPS" which is 170-280V (see picture). That is the only available setting (option) if I am not miataken.

It could have damaged a lot of my domestic equipment and I would like some advice on how to stop this from happening again.

No problems or errors up till now.

Regards, Gerhard

Hi GPvdB. My inverter is set on UPS. Haven't had any issues. Kodak King 5Kw

Thanks Jacques.

I just wish a could find a way to set the limits from 200V to 260V or something alike.

On 2023/07/20 at 9:49 PM, GPvdB said:

Surely the Inverter was supposed to not switch back to Line-Mode unless it can add power from the battery and give me an output of say 230V (there was at least 60% batt power available).

No. Unless you have a King model, which has double conversion, these models can't boost the AC-in; unless they are in battery mode, AC-in is connected to AC-out, so you get the same voltage out as in. They aren't designed to run with such poor utility power.

On 2023/07/20 at 9:49 PM, GPvdB said:

My interim solution was to change the Setting-03 to "UPS" which is 170-280V (see picture).

That's about the best that you can do.

Thanks for your reply Coulomb,

I was really under the impression that my Inverter - with enough battery backup (10kW), is the best solution to bad power inputs and to protect all appliances (fridges, computers etc. downstream with clean stabelised pure sine wave power within it's specs.

It was late night and my system was setup as SUB, and in Batt-mode at that stage because of "load shedding".

The switch back to Line-mode was a mess. I understand that the inverter (because of the low power input settings of 90 - 280V)  was allowed to switch back to line mode, but the least I expected was that:

1) The inverter stay in battery mode where it had enough power to supply to the house.

2) Or simbly blend in some battery power to conform with the output specs of the Kodak OG-7.2 (specified output voltage of 230V +- 5%).  

Do I maybe miss something?

Spending all this money and still have the same risk of damaging electronics, fridges etc doesn't make sense.

If this inverter really can't supply clean power reliabilly up to spec (or rather nothing at all if in trouble), then what else will do the job.

Any suggestions would be appreciated.

Regards,

Gerhard 

 

 

 

Sorry, it's a difficult problem, and one that I don't know much about.

You would think that a King with its double conversion would be ideal, but somewhere I read that it's not good for cleaning up the output from poor generators. Eskom with poor voltage regulation would look a lot like a poor generator, or potentially worse actually. I haven't had time to consider whether this suggestion is valid or not. I guess it all hinges on whether the King's power factor correction circuit can handle the low voltage of Bad Eskom. Perhaps despite the voltage being ridiculously low, the large size of the generators may mean that it's actually quite steady in frequency and therefore easy to lock on to and convert to DC bus voltage successfully. 

This shouldn't be a problem on the Sunsynk and Deye type of inverter, as they allow the grid parameters to be more precisely set i.t.o. Voltage and Frequency, such that if the grid is out of spec, it will not connect, but stay on battery and solar. Maybe this doesn't help here, but just saying that there are options.