Excess solar charging only

[liuping]

I'd like to get my powerwalls to charge only from excess solar, but they seem to always take 100% of the solar until full each the morning.

The Tesla web page says in Self Power mode, it should be charging from excess solar, but that does not work for me.

I'd really like to reduce the amount of solar pushed back on the web during the day. Due to a screw up by my installer, my credits are capped at 3.9kW, so anything after that is just free to the grid I get nothing, So I'd rather charge during that time for use later during Peak rates.

Has anyone figure out a way to get it to only ever charge from excess solar? I don't mind change modes and reserve level during the day (will set up a script to do that eventually)

My idea set up would be: hold off all charging until around 10am, then charge only excess solar until 4pm, then switch to the house running 100% Powerwall from 4-9pm, then 100% grid until 10am the next day.

 

[eml2]

What is your reserve level set to? In Self Power mode, all solar will go to PW until it hits the reserve level, then excess solar will go to PW until it is full. My PW is charged from excess solar all the times.

 

[cwied]

Are you setting your backup reserve to 100%? If you're below the backup reserve the algorithm is in backup mode. It'll only use the self-consumption algorithm above the reserve.

 

[liuping]

What is your reserve level set to? In Self Power mode, all solar will go to PW until it hits the reserve level, then excess solar will go to PW until it is full. My PW is charged from excess solar all the times.

View attachment 332472

I set the reserve lower than the current battery level this morning, but all power went to the battery until it was full. Your looks like it is doing what I want.

 

[liuping]

Are you setting your backup reserve to 100%? If you're below the backup reserve the algorithm is in backup mode. It'll only use the self-consumption algorithm above the reserve.

That's what I was hoping, but it went 100% to battery even when above the reserve.

Maybe it did not like that I changed the setting this morning. I'll try changing them tonight before midnight.

 

[liuping]

This did work well today. it adjusted the reserve to the current battery level when setting it into self consumption mode.

It charged just from excess solar until 100%, around noon.

That is better, but I still want to use more of the noon-2pm power, instead of putting it on the grid.

Next I'll try moving the peak rate TOU period to morning to block charging until 10am, then switch to Self Consumption mode. Hopefully the TOU periods are settable via the JSON api, so the whole thing can be automated.

 

[BJReplay]

Hopefully the TOU periods are settable via the JSON api, so the whole thing can be automated.

No one has worked out how to do this - and current thinking is that it isn't possible. If you work out how, please share!

 

[cwied]

I think liuping may be referring to the server-side JSON api, not the client-side one. It definitely should be possible to use that. The only issue is the (up to) one hour lag on changes. As long as you know what you want to do more than an hour in advance, it should be doable, though.

 

[liuping]

I think liuping may be referring to the server-side JSON api, not the client-side one. It definitely should be possible to use that. The only issue is the (up to) one hour lag on changes. As long as you know what you want to do more than an hour in advance, it should be doable, though.

Yes. I'm planning on using the server to set the reserve and modes. The delay is not much of an issue for what I need.