un explained usage

[Lyndon-63]

We have 11 kWh of solar panels and 27 kwh of battery storage. Even though it's a small amount, it adds up over the day, week, month, and quarter. I understand there's a small amount of grid usage when appliances are first turned on and in similar situations, and our battery app shows that. 

However, we're feeding power into the grid 24 hours a day while there is still power in the battery. The only time there is no grid consumption is when the battery is full and feeding everything into the grid; otherwise, it draws small amounts of grid power, for which we are charged. But the FIT taken from the battery doesn't really accumulate outside of the battery's overflow.  

I have screenshots every day for the last two months from the ALG app and the battery app as well. 

Any insight into this would be greatly appreciated, and it's normal.

[Lester]

Was a cloudy low production day I take it, Lyndon ?

Not enough to charge the battery fully, but more than likely enough to more than cope with your usage.

Or maybe that was the state of play at midnight (end of day), looks like an air cond / RC heat running periodically during the night ?

0.8kwh is nothing in the scope of things, when a battery switches over it's not instantaneous, you will draw little amounts from the grid at odd times, your inverter is a 10kw I take it, does it have fan cooling ?

"However, we're feeding power into the grid 24 hours a day while there is still power in the battery. "

How so ? Are you exporting in a VPP ?? Your battery is normally kept for your usage otherwise.

You did get the 17.56kwh feed in during solar hours, normal for solar only or solar / battery.

[Lyndon-63]

Hi Lester.

Will answer your questions here. 

"Was a cloudy low production day I take it, Lyndon?

"Not enough to charge the battery fully, but more than likely enough to more than cope with your usage." No they it was a Sunny Day 🙂 we generated 40.8 kWh on the 12th & fed 18.05 kWh back to the grid & 59.5 kWh on the 13th & fed 30.95 kWh back to the grid.

"Or maybe that was the state of play at midnight (end of day), looks like an air cond / RC heat running periodically during the night ?" Our battery was fully charged by 11 AM on both days. We do not have an air conditioner or heat pump, and our hot water is gas, which is why I question the power usage from the grid.

"0.8kwh is nothing in the scope of things, when a battery switches over, it's not instantaneous, you will draw little amounts from the grid at odd times, your inverter is a 10kw, I take it, does it have fan cooling?"

Yes, I understand the .8 kWh usage, but that usage is usually more than double in the AGL app. We have two inverters, a 6 kWh and a 5 kWh, on the two batteries that total 27 kWh 

"However, we're feeding power into the grid 24 hours a day while there is still power in the battery. "

"How so ? Are you exporting in a VPP ?? Your battery is normally kept for your usage otherwise.

You did get the 17.56kwh feed in during solar hours, normal for solar only or solar / battery."

We don't have a VPP or any other FIT that exports. It's only a small amount of power it exports back to the grid, but it was totalling about 1 kWh out of solar production hours between sundown and when we start to feed power back to the grid 

[Lester]

Your usage after hours is taken from the battery then, nothing to the grid from the battery, and these down to 78.6 and 81.6 kwh respectively at midnight in your graphs.

What are you running to give those peaks through the day from solar, and from the battery after hours, perhaps 2.5 to 5 kw through the day ?

I also have 2 x 5kw inverters, on 2 of our 3 phases . . . I'm not 100% sure if there is only the 5kw available for usage from solar with a master / slave setup, or if that sees us able to use up to 10kw form solar for usage, we hardly ever go over 4kwh or so usage if running a few things around noon.

I must remember to ask my solar guys . . .

If you use more than your inverter limit you draw from the grid (well, that's the rule with single inverters), you will draw at whatever the current usage rate is . . . and might also apply to multiples if setup is how I think it might be (master / slave).

I think you will find discrepancy between AGLs usage and yours at that level might be rough rounding.

You should be able to tally up your real usage from the next bill or from you data download if you wanted to do that.

You'll find the battery use has small gaps that will see power from the grid in switching, it's a tiny gap but many times a night like your graph shows will see the usage in those small amounts.

[Ellen261Rister]

Hello!

It’s normal for grid-connected solar battery systems to draw small amounts of grid power even when the battery has charge. This can happen due to inverter response delays, voltage regulation, or system settings that prioritize exporting solar. Feed-in Tariff (FIT) usually applies only to excess solar from panels, not battery discharge. Reviewing system settings or consulting your installer may help reduce unnecessary grid draw. 

[Lyndon-63]

Hi Lester 

Thanks for the reply. The load spikes are from a kettle and a microwave because we breed exotic parrots, which heat water for their formula, etc. 

On the graph for the 13th, there are only two small bumps in grid usage throughout the whole 24-hour period one at 8.35 am and the other at 9.35 am, no more than 0.12 kWh for a very short space of time, which may equate to the 0.67kWh recoded for the day, that's fair enough, but not the continuous drain from the grid that doesn't show that if calulate and add to the 0.67kWh recorded prety much matches AGL reding for consuption for the day.