I have installed a power consumption meter between the DB and the inverted to measure the Evkom consumption to the inverter.  (5kw inverter).  Albeit small, I have a consistent supply from the grid to the inverter even if the solar power generation is in excess of the load.  E.g.  Solar generation would be 1800w and the load 800w with power from the grid varying between 20w and 100w dependant on the charge state of the battery.  I have noted that the fuller the battery, the lower the grid consumption, however never zero although having lots of excess solar power.  Please can you assist with an explanation as to why there is always a small Evkom power usage?  Is this normal?  Thanks

You need to check the DIRECTION of the power, the inverter will always push/pull a small amount of power from the grid, usually around 20W-100W. It does this to "align" with the grid Frequency and voltage.

My 5kW inverter draws 45W from the grid when there is no sun but always pushes back/draws a small amount when there is PV.

43 minutes ago, Kalliew said:

I have installed a power consumption meter between the DB and the inverted to measure the Evkom consumption to the inverter.  (5kw inverter).  Albeit small, I have a consistent supply from the grid to the inverter even if the solar power generation is in excess of the load.  E.g.  Solar generation would be 1800w and the load 800w with power from the grid varying between 20w and 100w dependant on the charge state of the battery.  I have noted that the fuller the battery, the lower the grid consumption, however never zero although having lots of excess solar power.  Please can you assist with an explanation as to why there is always a small Evkom power usage?  Is this normal?  Thanks

What inverter do you have?

4 minutes ago, Basil Katakuzinos said:

What inverter do you have?

Must 5kw Hybrid PV 1800 VHM

50 minutes ago, FixAMess said:

You need to check the DIRECTION of the power, the inverter will always push/pull a small amount of power from the grid, usually around 20W-100W. It does this to "align" with the grid Frequency and voltage.

This. My hybrid system uses a small amount of grid power on even the sunniest of days.

When you think about it, this makes sense. These inverters have the ability to send spare power back to the grid to take advantage of resell tariffs. So if you think about it, the inverter has to, as @FixAMess points out, synchronise with the grid. If the grid is at 228V, then 228V is what we must send back. So this synchronisation requires drawing a little power from the grid as a sample.

I do not know that inverter so i cant help you change the grid set point but i can guarentee you that as @FixAMess has stated it is perfectly normal, you should be able to find a way to feed in the excess power if you want. 

Thanks for all the feedback.

3 hours ago, Bobster said:

So if you think about it, the inverter has to, as @FixAMess points out, synchronise with the grid.

Sorry, I disagree. It has to draw a tiny amount of power to sample the instantaneous amplitude, but that would be of the order of milliwatts.

My theory has been that it's because in most of South Africa (perhaps it is or will be changing soon), you are not allowed to export ANY power to the grid. So the inverter has to be cautious, drawing a little all the time, so that if a load suddenly stops, it won't accidentally push a burp of power back to the grid until it can adjust its power flow to suit the new load.

But if a large load comes off (say 2 kW), then drawing a few hundred watts won't help. Maybe it's something to do with how the meters work.

Considering South Africa's power problems, I think that allowing small amounts of power back to the grid would be a good thing, so I'm puzzled by this rule.

Thanks @Coulomb. That's a more plausible explanation.

Exporting is a matter of where one lives. In CT it is allowed and people do it. In Johannesburg (where I live) it is allowed but the tariffs make it not worth my while. So they allow it and discourage it at the same time. Starting with the special meter that I have to pay for. 

Thanks @Coulomb. That's a more plausible explanation.

Exporting is a matter of where one lives. In CT it is allowed and people do it. In Johannesburg (where I live) it is allowed but the tariffs make it not worth my while. So they allow it and discourage it at the same time. Starting with the special meter that I have to pay for. 

PS. So far today (it's 18:10 now) I've drawn 0.74 kw/h from the grid. 

Same thing with my inverter, also more noticeable at night (on batteries) than during the day (on PV).

There's a setting in the Mypower app where this behaviour can be fine-tuned, but it's such a small "leakage" that I haven't bothered:

Here's a bit more on how to do it with an InfiniSolar.

Edited October 14, 20214 yr by ChristoSnake
Added link to explanatory thread.

100% normal. Issue is if you are drawing a lot of power from PV/inevrter and the power draw stops. lets say a geyser drawing 3kw and you turn it off.. Then it takes a short while for the inverter/mppt to ramp down the power output. This obviously is an issue as your load is perhaps 100w and your inverter is ramping down from 3kw. The small amount the inverter draws from grid is there to prevent a small return spike to the grid. Some electricity meters will error when you feed power back to the grid. This prevents this from happening.

 

Anyways. that is hat I understand from Victron documentation

I've been looking at my data on SEMS portal for the last few days. It seems to me that when something big starts up, or something that has a big initial load then settles down (EG fridge motor) starts up then the system draws from the grid for a moment, presumably because it can deal with the spike in demand more quickly than by calling on batteries. 

The flies in that ointment are the heat pump and the pool pump. I don't see the little spike from grid that I do when say the kettle or the dishwasher turns on.