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Gen3 Home Charging with powerwalls

miimura

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Aug 21, 2013
7,314
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Los Altos, CA
In NEM2 PG&E land, I look at it as saving the NBCs by charging from surplus solar because your alternative is charging Off-Peak from the grid that would incur NBCs. The 3pm thing is not an issue for me. If I'm home to charge the car from surplus solar, I would be there to tell the car to stop charging or even unplug the car at 3pm.
 
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The main drawback of Charge HQ (aside from the kilometers thing) is:
They don't support the PG&E TOU rates. Their system does not realize that I'm punished by using solar to charge an EV starting at 3pm local time. So for now the software seems good, but I'll turn it off since I don't want to lose 3pm shoulder solar exports.

Can't you set those shoulder times as do-not-charge in the Charge HQ settings? My setup is vastly simpler so I haven't messed with any of the time schedules.

 
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holeydonut

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Jun 27, 2020
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East Bay NorCal
Can't you set those shoulder times as do-not-charge in the Charge HQ settings? My setup is vastly simpler so I haven't messed with any of the time schedules.



Ah ok I was trying to set the TOU under the Price Source and NEM Region options. I'll set up a "no charging from 3pm to midnight" rule. The app is back on heh.

If I assume an annual at home charging of 10,000 miles at 300 watt hours per mile (performance = zoom zoom), that's like $60 of avoided NBCs!
 
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I think the main benefits of Charge HQ are:
1) Reducing your NBCs for any grid export. I'm sure @Redhill_qik and @miimura will correct me, but I think you get hit with a ~$0.02 to $0.06 (off-peak vs peak) per kWh NBC when you export energy under normal NEM. So, you dodge this cost since you pushed to your car instead of to the grid.
The Non-Bypassable Charges (NBCs) are for the electricity that you import not for what you export and it is a non-TOU fixed amount that is currently $0.02423/kWh. Using the 300wH/mile and 10,000 miles numbers that would be 3,000 kWh, if this was all charged from midnight to sunrise it would incur $73.26 in NBCs This might be a real cost or if you are a net generator it would be less than the annual MDCs and not matter.
 
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holeydonut

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Jun 27, 2020
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East Bay NorCal
I have bad news to report on this front... but whatever is happening when the car is charging is taking my solar system offline. It's taking out all 23 of my micros; and it's really weird.

Here's a chart of my solar production and grid import/export on a sunny day.

My powerwalls charged from about 8am to 11:45am. From there, ChargeHQ attempted to charge the car. Unfortunately, you can see these weird production divots that correspond with times the ChargeHQ software wasn't able to exactly zero/balance out my home loads.

The home imports aren't massive spikes; something like 2 kW. Unfortunately there were enough to completely take my entire Enphase solar system offline at those times.

I lined it up with the "mini spikes" of the imports with the "big divots" of my solar production. Sorry for the hokey graph; the default app overlay sucks (the old app chart was so much better!)

1652724600785.png


Here's my production chart measured by the Enphase Envoy. Enphase recorded the same divots.
1652724835539.png



I've never encountered something like this under normal conditions (charging the the EV normally or running ACs real hard). Normal sunny day production is a nice curve no matter what I'm importing/exporting.

Anyway, I'm going to turn off this app for now.
 
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holeydonut

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Jun 27, 2020
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East Bay NorCal
Mini update on this ChargeHQ thing... I tried it again yesterday to try and better understand what could be happening where it seemingly takes my Enphase solar system offline. Unfortunately, I got hit with a separate bug.

This time once my car charging started (at 23A), the Tesla energy monitoring spazzed on me... and tesla app went offline so I just shut down Charge HQ again.

You can see in the images below, the solar data went to zero; the home use went to zero; and the Powerwalls ... just made no sense. But my home never actually lost power, and Enphase didn't show any interruption (unlike my previous posts where solar energy production was 0 for a few minutes causing the divots in the Enphase chart).

1653324714262.png


1653324847852.png


1653324890850.png



ChargeHQ has no historical telemetry, so I can't really show you what it was doing at the time just after noon. This thing is still beta and probably not worth relying on at this time. And maybe it works better with a Solaredge or Tesla Inverter.
 
You could also try manually starting charging and changing your car charging amps to see if you can reproduce the issue without ChargeHQ. I wonder if there's something about the way your charger is set up that is interacting strangely with other parts of your system. ChargeHQ seems not to have any side effects for me, but I have a SolarEdge, not an Enphase system.
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
You could also try manually starting charging and changing your car charging amps to see if you can reproduce the issue without ChargeHQ. I wonder if there's something about the way your charger is set up that is interacting strangely with other parts of your system. ChargeHQ seems not to have any side effects for me, but I have a SolarEdge, not an Enphase system.


If I take ChargeHQ out of the equation, I can't re-create the issue. I've tried to manually charge my Tesla at 6A... up to 48A and then tapping the charge rate value all over the place and being an idiot on the app. It goess fine... and my solar production is whatever was harvested by the 23 micros at that time. I can't re-create having my solar array shut off and stop producing unless I use ChargeHQ.

Which is weird, since ChargeHQ shouldn't be able to take my solar offline (it's an Enphase system that doesn't even talk to the Tesla hardware except reporting solar export via a CT). This is very weird indeed.
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
I found another possible solution to the "can an EV charge with excess solar" thing...

Emporia claim to have a level 2 charger that in the presence of an on-site solar array... the EV charger can instruct an EV or PHEV to modulate its charging/load. The goal is to use energy that would otherwise be backfed to the grid.


The "charge with solar" will also require the homeowner to install an Emporia Vue on the load side of the meter between where the solar backfeeds the home and the utility meter. This means none of this will work if your solar is a line-side tap.


I'm not in the market for a new EV charger at this time, but this does look promising once we enter a world where homes with solar are punished for backfeeding the grid (like California under NEM 3.0).
 

miimura

Well-Known Member
Aug 21, 2013
7,314
7,293
Los Altos, CA
I found another possible solution to the "can an EV charge with excess solar" thing...

Emporia claim to have a level 2 charger that in the presence of an on-site solar array... the EV charger can instruct an EV or PHEV to modulate its charging/load. The goal is to use energy that would otherwise be backfed to the grid.


The "charge with solar" will also require the homeowner to install an Emporia Vue on the load side of the meter between where the solar backfeeds the home and the utility meter. This means none of this will work if your solar is a line-side tap.


I'm not in the market for a new EV charger at this time, but this does look promising once we enter a world where homes with solar are punished for backfeeding the grid (like California under NEM 3.0).
An Emporia user says that he had a "less than stellar" experience with their solution. See below:

 

holeydonut

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Jun 27, 2020
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East Bay NorCal
An Emporia user says that he had a "less than stellar" experience with their solution. See below:



Goddamn...

I'm having less than stellar experience with ChargeHQ...
Tesla won't add the feature since Elon keeps laying people off (and the folks are working on the advanced features for Powerwalls!...
and Emporia seemed promising until I guess it wasn't.
 

DrGriz

Member
Sep 11, 2021
854
1,054
Idaho
Crossposting a bit here from the other thread on amperage:

I downloaded ChargeHQ and ran it yesterday. Intermittent clouds during charging. I have a Fronius inverter and Tesla Powerwalls x 3 with a Tesla Wall charger.

The system ran flawlessly as far as I can tell. Tanked up the Powerwalls and then charged the car almost purely from solar, adjusting for the intermittent clouds until it hit my 70% target for the car. I then made a 3 kWh trip to town late in the afternoon, plugged it in when I got home and the system topped it off. According to TeslaFi, charged at 43, 7, 17 and 13 amps, but I could see on ChargeHQ that it was micro adjusting the amperage. No problems with crashing the Inverter, etc. Yes there were intermittent spikes from the powerwalls due to sampling only every minute but they were tiny. I pulled only 0.2 kWh from the grid yesterday.

I have grandfathered into long term net metering, so there's no financial benefit for me to do this, only purity and bragging rights for solar only charging. :D
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,244
2,630
East Bay NorCal
Crossposting a bit here from the other thread on amperage:

I downloaded ChargeHQ and ran it yesterday. Intermittent clouds during charging. I have a Fronius inverter and Tesla Powerwalls x 3 with a Tesla Wall charger.

The system ran flawlessly as far as I can tell. Tanked up the Powerwalls and then charged the car almost purely from solar, adjusting for the intermittent clouds until it hit my 70% target for the car. I then made a 3 kWh trip to town late in the afternoon, plugged it in when I got home and the system topped it off. According to TeslaFi, charged at 43, 7, 17 and 13 amps, but I could see on ChargeHQ that it was micro adjusting the amperage. No problems with crashing the Inverter, etc. Yes there were intermittent spikes from the powerwalls due to sampling only every minute but they were tiny. I pulled only 0.2 kWh from the grid yesterday.

I have grandfathered into long term net metering, so there's no financial benefit for me to do this, only purity and bragging rights for solar only charging. :D


Your solar net metering doesn't hit you with "non bypassable charges" or anything of the sort as a flat fee to push energy to the Grid?
 
Friend getting solar quotes is asking if $900 extra for SolarEdge EV charger installed would be worth it on SolarEdge install (without ESS in this case). Not quite the exact same as OP's topic with Powerwalls, but SolarEdge claims a similar benefit of charging during the day on solar, to avoid NBC's. I'm not sure it works the same, might not be able to monitor home loads, so home loads might draw some from grid while all solar directed to EV charger, but that'd still be better than nothing. Anyone know if this feature works well, or disappointing like the Emporia one?

Seems not a bad deal they don't have an EV yet, but it'll work for Tesla or non-Tesla. Another friend just got a 14-50 installed for $600 around these parts, that's without the cost of a mobile or wall charger - and that was the simplest possible run just 4' from the panel. Also that friend couldn't even get any electrician to quote him extra to pull a permit, whereas I'm sure the SolarEdge installer will include the EV permitting in the larger solar install.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,244
2,630
East Bay NorCal
Friend getting solar quotes is asking if $900 extra for SolarEdge EV charger installed would be worth it on SolarEdge install (without ESS in this case). Not quite the exact same as OP's topic with Powerwalls, but SolarEdge claims a similar benefit of charging during the day on solar, to avoid NBC's. I'm not sure it works the same, might not be able to monitor home loads, so home loads might draw some from grid while all solar directed to EV charger, but that'd still be better than nothing. Anyone know if this feature works well, or disappointing like the Emporia one?

Seems not a bad deal they don't have an EV yet, but it'll work for Tesla or non-Tesla. Another friend just got a 14-50 installed for $600 around these parts, that's without the cost of a mobile or wall charger - and that was the simplest possible run just 4' from the panel. Also that friend couldn't even get any electrician to quote him extra to pull a permit, whereas I'm sure the SolarEdge installer will include the EV permitting in the larger solar install.


@hey kupo posted about the SolarEdge charger in that thread miimura linked to...


Kupo seems to have a very positive experience. It does seem to meter the home loads and know what energy is about to be pushed back across the meter. Cool charts are cool.
 
@hey kupo posted about the SolarEdge charger in that thread miimura linked to...


Kupo seems to have a very positive experience. It does seem to meter the home loads and know what energy is about to be pushed back across the meter. Cool charts are cool.
Great, good that the SolarEdge, and it seems newer Enphase Envoy monitoring (not my older model), all seem to come with consumption monitoring now - I guess they have inputs for a set of CT's around the wires to the meter...
 

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