Trickle Grid Import

[Steve Q]

Hi Everyone,

Great to be a part of the group.

I've a question if anyone can help.

I recently had a solar system fitted, details below:

6.5 kW rooftop array, 16 * JA MC 405w panels
Growatt 6.0 Hybrid Inverter
Growatt 6.5 kWh Li-ion battery

System is running great apart from one minor niggle. The system sometimes draws current from the grid even when the battery is fully charged. This isn't when there's a large load from the house, just seems to happen at random times e.g. middle of the night when nothing is drawing power. Currently drawing between 0.2 and 0.6 kWh per day.

Anyone had a similar experience or got any suggestions? Thanks.

Steve

[SunEagle]

Hello Steve Q and welcome to Solar Panel Talk

One option may be that when the grid "burps" a grid tie inverter will stop producing for a short period of time. It may be that at night this sometimes happens and a very small load (like the inverter) could be drawing from the grid instead of the battery before it reconnects to your equipment.

Just a suggestion. Coming up with the true reason may take some type of electrical analyzer that can record the time and event.

[Ampster]

Hi Everyone,

.......... The system sometimes draws current from the grid even when the battery is fully charged. This isn't when there's a large load from the house, just seems to happen at random times e.g. middle of the night when nothing is drawing power. Currently drawing between 0.2 and 0.6 kWh per day.

Anyone had a similar experience or got any suggestions? Thanks.

Steve

I have an Outback Skybox and see that occasionally. Outback technical support calls it slosh. I don't have a precise measurement like you do but it is trivial compared to the 30 kWh I send back to the grid every day on average in the summer. My power company charges in 15 minute increments so the net effect may be even less significant depending on when it occurs. I think my inverter has more overhead than that.

NOTE: Subsequently, I went to the PGE site and looked at the details for one day. There were a four time periods when I consumed 400 Watts and eleven when I produced 60 Watts. Both of those were when solar was not producing Net generation. That means on that day there was some solar production during 9 periods. Each measurement period for this data is one hour. My hybrid inverter is set to Self Consumption mode so it should not be consuming anything from the grid but it looks like the negative slosh could be a total of 1600 Watts and the positive slosh (generation) could total 660 Watts. Because some of my loads are outside of the current transformers of my hybrid inverters, some of that measured consumption could just be normal for those loads.