Prepaid meter drawing from battery during loadshedding

Is that a problem / question / issue?

Not maybe a meter with its own internal battery? Otherwise doesn't make sense because the meter should be on the non-essential side which is dead during loadshedding.

1 hour ago, mzezman said:

Is that a problem / question / issue?

I am so sorry, this post was sent in error. The issue is not "drawing power during load-shedding". I tried to edit and remove but failed. Please see the post below. 

I have recently replaced a 5kW backup inverter with a 4.6 kW Goodwe es hybrid inverter and a 5kW Freedom Won e Tower battery both working very nicely. I have 2 strings of 6 PV panels generating about 4 kW during midday hrs on a good day 

I have a granny flat wired with a sub DB and a prepaid meter with the light circuit on the inverter as essential load so that during load-shedding the client can have lights. The non-essentials (aircon, stove, geyser, kettle etc ) are not energised during load-shedding of course. 

However during normal operation when there is no load-shedding in the hrs of darkness or when PV input is low I have noticed that the non-essentials from the granny flat, draw power from the batteries. This is not desirable because during hrs of darkness or low PV input, the client could trip the system by utilising the non-essentials excessively without the main house realising.

Can anyone advise if or how this issue can be resolved? I presume it is a matter of wiring the sub-DB and or the granny flat non-essentials?

Thank you 

 

Ah ok - that's clearer. Is there a setting in the Goodwe to not export to Non-Essentials?

19 minutes ago, Bushtracker said:

However during normal operation when there is no load-shedding in the hrs of darkness or when PV input is low I have noticed that the non-essentials from the granny flat, draw power from the batteries. This is not desirable because during hrs of darkness or low PV input, the client could trip the system by utilising the non-essentials excessively without the main house realising.

I think this is the nature of the beast. I have the same inverter. I see, for example, on overcast days that the pool pump, which is on the non-essential side, starts running and the Goodwe will supply it with whatever it has available - usually grid as a last result. When the grid goes down, then nothing on the backed up side gets power, but as long as the grid is up, the Goodwe will try to keep everything running, even if it means drawing from the battery.

NB! I do have it set to not export, but that seems to mean that it doesn't push past the meter. 

What I do have is a setting to say that whilst there is grid, do not discharge the battery past X percent. In my case X = 40. So my battery will not discharge lower than 40%, and so that is the buffer that I always have in hand should an outage occur.

Just now, Bobster. said:

NB! I do have it set to not export, but that seems to mean that it doesn't push past the meter. 

IE you can set it to not export to GRID.

I will now go and check every single setting on PV master LOL.

It has this, whatever this is. 

52 minutes ago, Bobster. said:

It has this, whatever this is. 

OK thanks, Bobster, as I understand and know by experience is that in Back-up mode  the battery is not discharged unless to support back-up loads when the grid is unavailable.

I have mine set not to export as well.

I have checked during the day when solar is active and found that the Aircon, and geyser , which have their own breakers, do not draw from the batteries but only the appliances on the plug circuit draw from the batteries i.e. stove, kettles, microwave fridge etc.

1 hour ago, mzezman said:

Ah ok - that's clearer. Is there a setting in the Goodwe to not export to Non-Essentials?

I'm not sure yet but there is a setting to prevent exporting to the Grid, which is set so.

16 minutes ago, Bushtracker said:

I have checked during the day when solar is active and found that the Aircon, and geyser , which have their own breakers, do not draw from the batteries but only the appliances on the plug circuit draw from the batteries i.e. stove, kettles, microwave fridge etc.

Interesting. Thanks.

I know that it uses PV to service the non-essential loads when PV is available. I may be wrong about the battery.

I must test this. It will either require a nicely (or not) overcast day, or a night time test when PV can't come into play.

Could it be an option to re-positioning the Current Transformer such that it excludes the tenant's sub-DB from the non-essential loads that are supplied by the Goodwe inverter? The downside would be that you probably couldn't sell your PV power to  your tenant, but at least you wouldn't be draining your battery to supply it either.

1 hour ago, GreenFields said:

Could it be an option to re-positioning the Current Transformer such that it excludes the tenant's sub-DB from the non-essential loads that are supplied by the Goodwe inverter? The downside would be that you probably couldn't sell your PV power to  your tenant, but at least you wouldn't be draining your battery to supply it either.

Hmm will run that by the installer? thanks

On 2022/12/19 at 2:07 PM, Bobster. said:

Interesting. Thanks.

I know that it uses PV to service the non-essential loads when PV is available. I may be wrong about the battery.

I must test this. It will either require a nicely (or not) overcast day, or a night time test when PV can't come into play.

OK... so today my battery was charged by about 11:00. Load shedding ended at 12:30 and will not start up again until 18:00. About 13:00 a storm started coming in, the sky grew dark and PV production plummeted. The pool pump had come back on at 12:30, and whilst the sky was dark we had about a 1KW load in the house (most of this is the pool pump) and SOC dropped at 10% per hour. So it looks like the Goodwe is using the battery to fill the gap between available PV and the demand made by non-backed up circuits.

On 2022/12/19 at 2:17 PM, GreenFields said:

Could it be an option to re-positioning the Current Transformer such that it excludes the tenant's sub-DB from the non-essential loads that are supplied by the Goodwe inverter? The downside would be that you probably couldn't sell your PV power to  your tenant, but at least you wouldn't be draining your battery to supply it either.

 

On 2022/12/19 at 2:07 PM, Bobster. said:

Interesting. Thanks.

I know that it uses PV to service the non-essential loads when PV is available. I may be wrong about the battery.

I must test this. It will either require a nicely (or not) overcast day, or a night time test when PV can't come into play.

 

Thanks for your inputs GreenFields and Bobster - much appreciated, this issue is not yet resolved, and has come down, I think to completely isolating the tenant non-essentials from the inverter, and wonder if this is actually possible?

On 2022/12/19 at 10:16 AM, Bushtracker said:

I am so sorry, this post was sent in error. The issue is not "drawing power during load-shedding". I tried to edit and remove but failed. Please see the post below. 

I have recently replaced a 5kW backup inverter with a 4.6 kW Goodwe es hybrid inverter and a 5kW Freedom Won e Tower battery both working very nicely. I have 2 strings of 6 PV panels generating about 4 kW during midday hrs on a good day 

I have a granny flat wired with a sub DB and a prepaid meter with the light circuit on the inverter as essential load so that during load-shedding the client can have lights. The non-essentials (aircon, stove, geyser, kettle etc ) are not energised during load-shedding of course. 

However during normal operation when there is no load-shedding in the hrs of darkness or when PV input is low I have noticed that the non-essentials from the granny flat, draw power from the batteries. This is not desirable because during hrs of darkness or low PV input, the client could trip the system by utilising the non-essentials excessively without the main house realising.

Can anyone advise if or how this issue can be resolved? I presume it is a matter of wiring the sub-DB and or the granny flat non-essentials?

Thank you 

 

 

you may need to rewire the sub-DB and/or the granny flat non-essential loads so that they are not connected to the battery system during normal operation. One solution could be to install a separate breaker for the non-essential loads, which can be turned off during periods of low PV input or darkness, so that the batteries are not drained. Additionally, you could install a monitoring system to monitor the battery state of charge and the usage of the non-essential loads, so that you can take action if the battery state of charge drops below a certain level.

Thank you I am going to look into separating the tenant from the inverter completely.

Thanks everyone - issue resolved!

We connected the Prepaid meter directly from the house side of the utility meter(Eskom), and then on to the subDB main for the granny flat, thus separating the tenant completely from the inverter, and so too, the CT meter.

 

 

On 2022/12/19 at 2:17 PM, GreenFields said:

Could it be an option to re-positioning the Current Transformer such that it excludes the tenant's sub-DB from the non-essential loads that are supplied by the Goodwe inverter? The downside would be that you probably couldn't sell your PV power to  your tenant, but at least you wouldn't be draining your battery to supply it either.

 As the CT meter is clamped at the point of entry from the utility on the main DB, the only way to isolate (exclude) prepaid meter and the tenants sub DB , is to draw power for the tenant directly from the house-side of the Utility meter, via the prepaid meter.