Smart Solar Charging

[markboris]

Yes everything connected properly. I sent them the screenshots and they confirm the Vue is seeing the power going back to the grid and it does match up with what Tesla is displaying.

I sometimes see controlled by excess solar but not all the time. This morning it starts charging immediately even though the Powerwall is not fully charged and it has yet to sell back any power.

Frustrating. Hopefully the fix is not long off. They did not have a ETA just said it is taking longer than expected.

As soon as solar starts generating in the morning, the Powerwalls start charging on the excess solar. Around 10:00-10:30am they are fully charged then I plug in the EV charger which charges the car on excess solar. I don't charge all that often, maybe once or twice a week. If I happen to need a charge anytime there is not excess solar, the Powerwalls charge the car.

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[skiingj]

My Emporia app looks the same as Mark's.

Right now mine is showing excess solar but it is draining the Powerwall’s:

 

[skiingj]

John: Are you certain about this? First, if you look under "Settings" on the Tesla app, you'll see "Powerwall" where you can set it to "Self-Powered" or "Time-Based Control".

Also, if you have PGE or SMUD, you will almost certainly have peak, near-peak, and off-peak electricity rates. There's a big difference among the rates and you'll save a lot by setting your apps to make sure you never draw from the grid during peak or near-peak hours!

The city of Roseville has its own power company. We are not managed by Cal ISO which is nice, no blackouts and much cheaper rates. Here are screenshots of Time Based Controls:

 

[skiingj]

As soon as solar starts generating in the morning, the Powerwalls start charging on the excess solar. Around 10:00-10:30am they are fully charged then I plug in the EV charger which charges the car on excess solar. I don't charge all that often, maybe once or twice a week. If I happen to need a charge anytime there is not excess solar, the Powerwalls charge the car.

What would happen if you leave the MME plugged in overnight? If I understand the current operations of the Vue/Charger it should not charge the MME until it starts to see power going back to the grid.

 

[markboris]

What would happen if you leave the MME plugged in overnight? If I understand the current operations of the Vue/Charger it should not charge the MME until it starts to see power going back to the grid.

Nothing. It would not charge until there is excess solar. I sometimes plug it in before the Powerwalls are charged if I have to leave early in the morning but if not I’ll just wait until they are.

 

[skiingj]

I am resetting the Time-Base Control to test out adding Time of Use. Any suggestions for a timeframe to better manage this thing?

 

[markboris]

I am resetting the Time-Base Control to test out adding Time of Use. Any suggestions for a timeframe to better manage this thing?

When I had fewer Powerwalls and had mine on Time-Based. I set it for the peak times of my TOU plan which was 4-9pm. That way the Powerwalls would run during that time if there was not enough solar. They would also have a mind of their own and sometimes continue running past 9 if I had used more grid power than normal. The Powerwalls would balance it out.

 

[markboris]

Hey John, I'm back home and took a couple of screen shots this morning. I'll be here only today and going out of town tomorrow again for a week. If there's anything you want me to take photos of in my breaker boxes let me know.

10:26 AM
Powerwalls almost charged at 99%. They are taking longer to charge as I have the dryer and whole house fan on which is consuming a bit of power.

10:26 AM
Emporia EV charger has been plugged into the car since yesterday when I got home and is paused waiting for excess solar. I could tap to charge now but I only want to charge on excess solar.

10:35 AM
Powerwalls fully charged, solar panels at full output, dryer off but whole house fan still on. While the Tesla app shows 10.1kW going to the grid, it is actually going to the EV charger which is in the main breaker panel. The solar inverter and Powerwalls are in the backup breaker panel.

10:35 AM
Emporia EV charger charging on excess solar

Here is my history from yesterday when I got home. I plugged in the EV charger at 2:17 PM and you can see it started and stopped 4 times. This was because I did laundry when I got home and of course the sun was going down so excess solar was not abundant.

 

[ridgebackpilot]

Mark: Your system looks and functions remarkably similar to mine.

The only remaining problem I still have to solve is the need to switch my Tesla Gateway settings from "Self Powered" to "Time-based Control" to avoid draining the Powerwalls when my Emporia charger kicks on.

As we discussed earlier, I suspect you avoid this issue because you have a separate backup panel to which your Powerwalls are connected. I'm still trying to figure out how to leave my Gateway set to "Self Powered" and avoid having the Powerwalls drained when the charger starts up.

To avoid this problem, perhaps eventually I will need to install a backup ("critical loads") panel. But I still want the Powerwalls to power my house at night to the extent possible.

I've often wished that I was more competent in electrical engineering...

 

[markboris]

Mark: Your system looks and functions remarkably similar to mine.

The only remaining problem I still have to solve is the need to switch my Tesla Gateway settings from "Self Powered" to "Time-based Control" to avoid draining the Powerwalls when my Emporia charger kicks on.

As we discussed earlier, I suspect you avoid this issue because you have a separate backup panel to which your Powerwalls are connected. I'm still trying to figure out how to leave my Gateway set to "Self Powered" and avoid having the Powerwalls drained when the charger starts up.

To avoid this problem, perhaps eventually I will need to install a backup ("critical loads") panel. But I still want the Powerwalls to power my house at night to the extent possible.

I've often wished that I was more competent in electrical engineering...

Michael, even though my Powerwalls are in my backup panel, they power the entire house including the breakers in my main panel with the exception of the EV charger. Why that is, I have no idea. My dryer breaker, along with the hot tub, oven and a few other breakers are in the main panel right next to the breaker for the EV chargers but the charger only charges on excess solar not the Powerwalls at any time. I am actually confused how this works also but it does work. It makes no difference if I have the Powerwalls set to time-based or self-powered the EV charger works the same. I still think it has to do with the Gatway 1 that I have and you guys have the newer Gateway 2. Let me know if there is any testing or changing around configurations you want me to do.

 

[ridgebackpilot]

Michael, even though my Powerwalls are in my backup panel, they power the entire house including the breakers in my main panel with the exception of the EV charger. Why that is, I have no idea. My dryer breaker, along with the hot tub, oven and a few other breakers are in the main panel right next to the breaker for the EV chargers but the charger only charges on excess solar not the Powerwalls at any time. I am actually confused how this works also but it does work. It makes no difference if I have the Powerwalls set to time-based or self-powered the EV charger works the same. I still think it has to do with the Gatway 1 that I have and you guys have the newer Gateway 2. Let me know if there is any testing or changing around configurations you want me to do.

Thanks, Mark. I suspect the critical difference between our systems is that your Powerwalls are isolated from your Emporia charger and mine are not.

In theory, it would be relatively easy for me to fix this and prevent the charger from inadvertently draining the Powerwalls. Currently, my Emporia charger has no way of differentiating between electricity coming from excess solar production and the Powerwalls. That's why I have to set the Gateway on "Time-Based Control" so that it isolates the Powerwalls during off-peak hours.

Absent rewiring my breaker panels to look more like yours, I can't figure out whether there's another way to set up my system to prevent the charger from draining the Powerwalls...

 

[markboris]

Thanks, Mark. I suspect the critical difference between our systems is that your Powerwalls are isolated from your Emporia charger and mine are not.

In theory, it would be relatively easy for me to fix this and prevent the charger from inadvertently draining the Powerwalls. Currently, my Emporia charger has no way of differentiating between electricity coming from excess solar production and the Powerwalls. That's why I have to set the Gateway on "Time-Based Control" so that it isolates the Powerwalls during off-peak hours.

Absent rewiring my breaker panels to look more like yours, I can't figure out whether there's another way to set up my system to prevent the charger from draining the Powerwalls...

I'm not sure how my charger differentiates between the Powerwalls and solar. Maybe because the Gateway is in between the main panel and the backup panel but that still does not make sense. I really don't know. Sometimes I get confused by these things. If someone else wants to try and figure this out, let me know. I can take photos and do some digging around.

 

[jesaf00]

So, here is another scenario. I have a recently installed Tesla solar and 3x Powerwall 3 with a Tesla backup switch (not gateway). Any idea what equipment I would use for this and my Mach E? I assume I would just attach to the incoming Tesla lines in the top of the main panel that are connected to the mains coming from the backup switch?

I would like to replace my EV charger with Emporia and use the excess solar for charging.

 

[spgordon57]

I would caution you almost sole reliance on solar power to charge your EV, to the exclusion of fully charging your batteries, since the EV battery has a much higher capacity than your home batteries. If you have 3 batteries, your MME battery still has 3X as much energy storage capacity. Think of the reverse: you want to be able to charge your home batteries from your EV, or use your EV battery as a fourth home battery, when necessary.

 

[markboris]

So, here is another scenario. I have a recently installed Tesla solar and 3x Powerwall 3 with a Tesla backup switch (not gateway). Any idea what equipment I would use for this and my Mach E? I assume I would just attach to the incoming Tesla lines in the top of the main panel that are connected to the mains coming from the backup switch?

I’m not understanding your question. Do you already have an EV charger and want to know where to connect it or want a suggestion on EV chargers that take advantage of excess solar charging?

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