Can I charge with excess solar only without draining my Powerwall 3?

[astrorob]

I asked Emporia of this and was told that the device is unable to tell the difference between battery usage and solar generation. As they do not have access to Tesla API, they informed this is not a scenario they would support.

is your PW set for self-powered mode? i ask because mine is set to Time-Based control which causes it to exclusively charge while solar is being produced. in this mode the PW won't ever discharge until peak hours occur. if you ran in this mode i think mach-lee's idea would work, because any excess going to the grid after the powerwall has reached 100% will be solar and not battery.

but if you need to run self-powered for NEM3 purposes then you'd probably have to come up with some hack to switch modes based on solar production, and i don't see anything in NetZero that would support that.

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[mke]

I set mine to Time-Based. The Powerwall will charge until full, and will start to discharge when solar is less than the power drawn. It will also draw from grid temporarily when the load is greater (maybe a spike to 5 kWh or more).

I didn't get the Emporia CT clamps to try because Emporia said it won't work - https://shop.emporiaenergy.com/prod...e-sensors-for-gen-3-vue-power-supply-included

Meanwhile, I am able to get evcc to read Powerwall 3 status through Tesla's own API. Looks like a nifty tool.

is your PW set for self-powered mode? i ask because mine is set to Time-Based control which causes it to exclusively charge while solar is being produced. in this mode the PW won't ever discharge until peak hours occur. if you ran in this mode i think mach-lee's idea would work, because any excess going to the grid after the powerwall has reached 100% will be solar and not battery.

but if you need to run self-powered for NEM3 purposes then you'd probably have to come up with some hack to switch modes based on solar production, and i don't see anything in NetZero that would support that.

 

[markboris]

mke, I just come on here and saw your thread. I have Emporia Chargers and 4 Powerwalls. The Powerwalls are setup on Self-Powered mode. When I have my chargers set to charge on excess solar only, that is what they do. They never pull from the Powerwalls.

 

[mke]

That's great to hear! Thanks. Does it mean getting this set of sensors for the main?

mke, I just come on here and saw your thread. I have Emporia Chargers and 4 Powerwalls. The Powerwalls are setup on Time-Based mode. When I have my chargers set to charge on excess solar only, that is what they do. They never pull from the Powerwalls.

 

[markboris]

That's great to hear! Thanks. Does it mean getting this set of sensors for the main?

I do have those and the Emporia Vue Energy monitoring system but I also have three breaker panels. My system is set up differently than yours. I have a main panel which the Emporia chargers are part of along with other 240 appliances in the home. Then I have a backup panel that the rest of the house is on including the Powerwalls and solar. Then I have a sub panel that takes care of the rear of the home. There is a thread here we talked about all of this about 2 or more years ago. There were others with your issue and it was the way the system was configured. I'll try to find it.

 

[markboris]

Here it is. Now have to find the post were we talked about configuring for excess solar without the powerwalls discharging.

https://www.macheforum.com/site/threads/smart-solar-charging.28181/

 

[Nikos]

I'm looking to charge my car from excess solar only. I have battery storage and I do not want the car to be charged from the home battery. I can't figure out a workable way and would like to see if anyone has any recommendations.

I am currently using an Emporia EV Charger.

Setup - please refer to the diagram

• The house has full backup with a Powerwall and the Tesla Backup Switch.
• All loads, including the EV charger, are on the same main panel.
• Powerwall is hooked to the main panel, and it does not distinguish between power from solar (inverter) or power from battery.

Problem

I was informed by Emporia that solar only charging is not possible with the Powerwall. Since the device cannot tell whether power is supplied by solar generation or battery usage, it is unable to determine what is excess solar. While it will not draw on the grid, it will drain the Powerwall. I do not want it to do that.

I took a look at Charge HQ (https://chargehq.net) and am reaching out to understand if this usage can be supported. It will mean getting a different charger as well as paying a monthly subscription if it works. Meanwhile, I wonder if anyone has solved this similar problem.

Thanks in advance for your help!

Hello Mike.
I have a similar setup at my house.
I have the Enphase system, battery storage, Grid switch and 28 solar panels with Enphase micro inverters.
If I wanted to do what you want to do with the excess power, I put my storage system on the “backup mode “, which locks the batteries to a full charge, with the excess energy going to the grid or used by the vehicle or your home.
If the vehicle draws more than the S panels can provide, then the extra draw comes from the grid.
You probably have a TWO way power meter installation, and can watch the power transfer in real time.
That is how you can setup your system,
if it is capable of with the Powerwall.
This setup might not be capable of in certain regions of the US. I don’t know what options you have with your Tesla Powerwall and the region you live in.
It is also the interconnection agreement with your power provider that dictates what you can do with that excess power of your panels.
Enphase prioritizes the loading of the storage batteries first and then the excess to the home or grid, which may include the EV when it is plugged with your charger.

 

[Charge_Rob]

Are you using Enphase microinverters? If so, you may (or may not) be able to do what you want using the relatively new Enphase IQ EVSE. I only briefly looked at them as they are definitely on the pricey side.

If they had an Enphase IQ battery, I think this would be the answer. But I don't see how Enphase would know what the Powerwall is doing any better than Emporia can?

 

[astrorob]

I set mine to Time-Based. The Powerwall will charge until full, and will start to discharge when solar is less than the power drawn. It will also draw from grid temporarily when the load is greater (maybe a spike to 5 kWh or more).

i wonder if this is because you are on NEM3, because that behavior is different for me. the PW won't discharge until peak pricing occurs at 4pm. at that time the PW output power is equal to the sum of the max grid output rate (5KW for me) and whatever the house is drawing. it's rare that i exceed 10KW in this setup (2 powerwalls), so grid output is continuous until the powerwall reaches its reserve. on NEM1 this is desired behavior because of the parity between buy and sell prices.

 

[apwelsh]

I'm looking to charge my car from excess solar only. I have battery storage and I do not want the car to be charged from the home battery. I can't figure out a workable way and would like to see if anyone has any recommendations.

I am currently using an Emporia EV Charger.

Setup - please refer to the diagram

• The house has full backup with a Powerwall and the Tesla Backup Switch.
• All loads, including the EV charger, are on the same main panel.
• Powerwall is hooked to the main panel, and it does not distinguish between power from solar (inverter) or power from battery.

Problem

I was informed by Emporia that solar only charging is not possible with the Powerwall. Since the device cannot tell whether power is supplied by solar generation or battery usage, it is unable to determine what is excess solar. While it will not draw on the grid, it will drain the Powerwall. I do not want it to do that.

I took a look at Charge HQ (https://chargehq.net) and am reaching out to understand if this usage can be supported. It will mean getting a different charger as well as paying a monthly subscription if it works. Meanwhile, I wonder if anyone has solved this similar problem.

Thanks in advance for your help!

When solar generation is charging the power wall and you plug your EV in to charge it, that does not turn off solar. The solar panels are still producing electricity, and the power wall will charge with whatever is being provided to it.
I am having a hard time reconciling this issue. If solar is producing 40 A of output and the house is consuming 10 A then the battery is gonna charge with the remaining 30 A. If you plug an EV in that wants 50 A then the net is gonna come as 10 amp draw from the battery or from the utility company. I think it really comes down to what tuning capabilities you have with the power wall now when the solar panels are producing more than. The 50 A that your charger is drawing what’s left over should by the power wall. Any such logic shit exist within the power wall itself since it is up to the power wall to decide when to kick in and behave as a generator very common set up for the power wall is to charge the power wall at night when electricity is at its lowest price and then use it during the day to power the home. Another comment scenario is to charge the power wall during the day off of solar and then power, the house off of the battery at night. The only thing in system that could make the decision on how it’s operating is the power wall itself so I would go back to the power wall and see what its capabilities are.
This message was typed using Siri dictation so if the grammar is off, I apologize

 

[music_cities]

I'm looking to charge my car from excess solar only. I have battery storage and I do not want the car to be charged from the home battery. I can't figure out a workable way and would like to see if anyone has any recommendations.

I am currently using an Emporia EV Charger.

Setup - please refer to the diagram

• The house has full backup with a Powerwall and the Tesla Backup Switch.
• All loads, including the EV charger, are on the same main panel.
• Powerwall is hooked to the main panel, and it does not distinguish between power from solar (inverter) or power from battery.

Problem

I was informed by Emporia that solar only charging is not possible with the Powerwall. Since the device cannot tell whether power is supplied by solar generation or battery usage, it is unable to determine what is excess solar. While it will not draw on the grid, it will drain the Powerwall. I do not want it to do that.

I took a look at Charge HQ (https://chargehq.net) and am reaching out to understand if this usage can be supported. It will mean getting a different charger as well as paying a monthly subscription if it works. Meanwhile, I wonder if anyone has solved this similar problem.

Thanks in advance for your help!

Do you have the Emporia VUE energy monitor?

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