Powerwall tab in the App

[Dave101]

I am on the Tesla Energy Plan, which works really well for me, and am starting to prepare for the Octopus Flux scheme, which also looks good.

I have started to try to gain a better understanding of the data which I can download from the App to see what else I can learn about how the system functions.

I have become confused by the "Powerwall" tab on the Energy screen.

TEP sets the battery reserve to 20%. If the capacity of the battery is 13.5KwH, then 20% should be 2.7KwH. Is that correct, or is there some other hidden storage?

If this is correct, then I should need to add 10.8kwH to make the battery full again.

I have put the data into Excel and,, for example, on 23rd December TEP started to load the battery again from the grid at 01:30 with a reading of 3.4kw in a 5 minute window, which I have dived by 12, to give the KWH figure of .2833.

The challenge is that when I add the imported energy back in, I reach a total which is greater than 13.5KW. (13.98). TEP then starts to empty out again and, by the end of the cycle, the battery is now showing less than 2.7 kwH (1.66)

So, having started off at 2.7, we have "exceeded" the capacity by almost .5 KwH "on the way up" and then lost more "on the way down"

I suppose that I should account for the energy loss in the battery and assume that 10% of the power going in is lost, but this makes the total too small.

Any thoughts on my process and what I am missing?

Thanks!!

 

[power.saver]

I am on the Tesla Energy Plan, which works really well for me, and am starting to prepare for the Octopus Flux scheme, which also looks good.

I have started to try to gain a better understanding of the data which I can download from the App to see what else I can learn about how the system functions.

I have become confused by the "Powerwall" tab on the Energy screen.

TEP sets the battery reserve to 20%. If the capacity of the battery is 13.5KwH, then 20% should be 2.7KwH. Is that correct, or is there some other hidden storage?

If this is correct, then I should need to add 10.8kwH to make the battery full again.

I have put the data into Excel and,, for example, on 23rd December TEP started to load the battery again from the grid at 01:30 with a reading of 3.4kw in a 5 minute window, which I have dived by 12, to give the KWH figure of .2833.

The challenge is that when I add the imported energy back in, I reach a total which is greater than 13.5KW. (13.98). TEP then starts to empty out again and, by the end of the cycle, the battery is now showing less than 2.7 kwH (1.66)

So, having started off at 2.7, we have "exceeded" the capacity by almost .5 KwH "on the way up" and then lost more "on the way down"

I suppose that I should account for the energy loss in the battery and assume that 10% of the power going in is lost, but this makes the total too small.

Any thoughts on my process and what I am missing?

Thanks!!

There are charging losses in the battery. It's about 90% efficient, so you have to put about 10% more in to get the equivalent out.

Also, the percentages at the bottom end of the reserve are offset, and at 20% in the app, the battery is actually at 24%.

In your case, to go from 24% to 100% would require 1.10 x (0.76 x 13.5) = 11.3kWh, which is about 1.1kWh extra to cover the losses.

 

[Dave101]

Thanks

This is really helpful. I will play with my spreadsheet again!