Charging with "excess solar energy" (without Powerwall)

[Velums]

Now that I'm on solar with NEM2, I believe I'll be paying "non-bypassable charges" when charging at night using power generated during the day. These are small, but they add up - I'm calculating about $180 a year for 25,000 miles.

One way to avoid this is to charge during the day and constantly adjust the charging rate to match the solar generation. But that's a lot of work, so I've been looking for a "set and forget" solution.

There are some EV chargers (e.g. from Emporia, Wallbox, and probably others) that can supposedly charge a car using the excess power that would otherwise be sent to the grid. They do this by measuring the output through the electric main or communicating with a PG&E Smart Meter and adjusting the power delivered through the EV charger to keep the net exported power at around zero.

These seem like they would save money (by avoiding non-bypassable charges), and they'd also avoid using/straining the grid (which proponents of "NEM3" claim is a big deal that needs to be paid for).

Does anyone have experiences with these types of chargers or this type of charging strategy?

If grid usage is such a big deal (see discussion about NEM3), I also wonder why this this charging strategy isn't promoted more, and why there aren't incentives to install them.

 

[miimura]

The Emporia solution looks very straight forward with their energy monitor and EVSE.

I was unable to find what is actually required to enable the Eco (surplus solar) feature on the Wallbox EVSE. They don't specify on the product web pages which energy monitoring devices are supported.

The most famous overseas solution that does this is Zappi, but it's not available in North America.

I agree that these solutions are very beneficial, but since California is still basically a Net Metering State, there is little financial incentive to push these solutions. With the combination of demand response (disabling charging during Flex Alert events) and reduced feed in credits that are likely in NEM 3, we will likely see these solutions proliferate.

I am particularly disappointed that Tesla has not enabled this feature for their customers. They clearly have all the data required from their solar and Powerwall customers and they could easily implement a cloud based solution to modulate the charging in their cars, yet they haven't. Bonus points for communicating directly with a Tesla Wall connector to modulate the pilot signal so that any connected car's charging can be adjusted to available solar surplus.

 

[Tazzman]

The Emporia solution looks very straight forward with their energy monitor and EVSE.

My experience with the Emporia solution has been less than stellar! I worked with their tech support for a while and they have been unable to make it work for me or explain what was wrong. I'm happy with both of their products except that the charge from excess solar feature does not work for me.

 

[miimura]

My experience with the Emporia solution has been less than stellar! I worked with their tech support for a while and they have been unable to make it work for me or explain what was wrong. I'm happy with both of their products except that the charge from excess solar feature does not work for me.

I knew it was a new product, but hearing that it is not working properly is definitely disappointing. Do they tell you they're still working on it?

 

[hey kupo]

I use my SolarEdge charger in solar-only mode. It adjusts to production/home usage pretty well. The big blue self-consumption periods are two separate charging sessions.

 

[Velums]

My experience with the Emporia solution has been less than stellar! I worked with their tech support for a while and they have been unable to make it work for me or explain what was wrong. I'm happy with both of their products except that the charge from excess solar feature does not work for me.

That's unfortunate to hear, since the Emporia solution seems to be one of the easier solutions to install and less expensive, too.

What issue(s) did you encounter with their excess solar feature? How long has it been since tech support worked with you on it?

 

[Tazzman]

That's unfortunate to hear, since the Emporia solution seems to be one of the easier solutions to install and less expensive, too.

What issue(s) did you encounter with their excess solar feature? How long has it been since tech support worked with you on it?

They are unable to get a working algorithm for the charging from solar it just jumps all over the place. The last email exchange with them was the end of February this year stating they don’t have reports from other customers of issues utlizing excess solar. I first emailed them the beginning of November 2021. I would be very interested in hearing frome someone who has it work for them but have not found that on my limited search.

 

[Velums]

I use my SolarEdge charger in solar-only mode. It adjusts to production/home usage pretty well. The big blue self-consumption periods are two separate charging sessions.

View attachment 810096

Do you have a SolarEdge standalone charger that communicates with the inverter? Or is it an inverter with an integrated charger?

 

[Velums]

They are unable to get a working algorithm for the charging from solar it just jumps all over the place. The last email exchange with them was the end of February this year stating they don’t have reports from other customers of issues utlizing excess solar. I first emailed them the beginning of November 2021. I would be very interested in hearing frome someone who has it work for them but have not found that on my limited search.

Thanks for attaching the graphs. It's not encouraging to hear.

It looks as though the charger bounces back and forth between charging too much and too little in order to average it out to zero. It seems like it wouldn't be that hard to adjust the algorithm with a software update to smooth it out some, but maybe it's not a priority for them.

Are you happy with everything else about the Emporia system?

 

[Tazzman]

Thanks for attaching the graphs. It's not encouraging to hear.

It looks as though the charger bounces back and forth between charging too much and too little in order to average it out to zero. It seems like it wouldn't be that hard to adjust the algorithm with a software update to smooth it out some, but maybe it's not a priority for them.

Are you happy with everything else about the Emporia system?

I'm very happy with Gen2 Vue energy monitor and the information it gives me. The charger works fine but without the excess solar part working I probably would have went with the Tesla. Maybe if I ever have an electric car that is not Tesla I will be happy I have the Emporia??

 

[hey kupo]

Do you have a SolarEdge standalone charger that communicates with the inverter? Or is it an inverter with an integrated charger?

The former, standalone charger.

 

[Watts_Up]

Charging with "excess solar energy" (without Powerwall) ​

Unless you work at home, without battry you need to have two EVs, driving one while the other get charged during the day.

 

[rrolsbe]

Now that I'm on solar with NEM2, I believe I'll be paying "non-bypassable charges" when charging at night using power generated during the day. These are small, but they add up - I'm calculating about $180 a year for 25,000 miles.

One way to avoid this is to charge during the day and constantly adjust the charging rate to match the solar generation. But that's a lot of work, so I've been looking for a "set and forget" solution.

There are some EV chargers (e.g. from Emporia, Wallbox, and probably others) that can supposedly charge a car using the excess power that would otherwise be sent to the grid. They do this by measuring the output through the electric main or communicating with a PG&E Smart Meter and adjusting the power delivered through the EV charger to keep the net exported power at around zero.

These seem like they would save money (by avoiding non-bypassable charges), and they'd also avoid using/straining the grid (which proponents of "NEM3" claim is a big deal that needs to be paid for).

Does anyone have experiences with these types of chargers or this type of charging strategy?

If grid usage is such a big deal (see discussion about NEM3), I also wonder why this this charging strategy isn't promoted more, and why there aren't incentives to install them.

I read somewhere in the past where someone did what you want with a Gen1/2 Tesla Wall Connector and a Raspberry Pi. I think they used the serial control connection normally used by the Master WC to talk to the Slave WC. Not sure if this would work on a Gen3 WC or if the two pin wired serial connector is present or functional?

 

[bedoig]

I read somewhere in the past where someone did what you want with a Gen1/2 Tesla Wall Connector and a Raspberry Pi. I think they used the serial control connection normally used by the Master WC to talk to the Slave WC. Not sure if this would work on a Gen3 WC or if the two pin wired serial connector is present or functional?

I've seen a couple threads where people were using the Tesla API to adjust amperage up/down in coordination with a home energy monitor (Sense, or similar). I think these two were the ones I'd browsed through before, and I think both had code available on GitHub:

TesSense - Control your Tesla charging from your Sense Energy Monitor

I have a Sense Energy Monitor that shows me how much solar power I am generating and how much energy my home is using every microsecond. It is nice for logging and realizing I have left the oven on but I would REALLY love if I could have it calculate any free solar and instead of sending it back...

teslamotorsclub.com

Any Downside To (Relatively) Frequent Amperage Changes During Charging?

I've written a small python program that periodically 1/ looks at our electric meter to see if we're sending power (from our solar panels) to the grid or pulling from the grid and then 2/ adjusting Tesla charging (either starting charging, stopping charging, or changing amperage) so we minimize...

teslamotorsclub.com

 

[bedoig]

If grid usage is such a big deal (see discussion about NEM3), I also wonder why this this charging strategy isn't promoted more, and why there aren't incentives to install them.

Regarding this part specifically, it's because grid maintenance costs are largely fixed, not usage dependent, but the tariffs are written in a way that assumes typical home usage without solar. That's the whole point that supporters of NEM3 are making. Solar owners bypass a lot of the usage based charges that cover fixed grid costs but 'freeload' and get to keep their grid-tie for backup. I don't know whether the amounts are fair, but the idea seems at least somewhat reasonable to me to avoid over-burdening lower income households who can't afford solar. It's essentially adjusting the tariff to a higher base charge for customers with solar rather than relying on usage derived fees to cover costs.

 

[holeydonut]

I'm very happy with Gen2 Vue energy monitor and the information it gives me. The charger works fine but without the excess solar part working I probably would have went with the Tesla. Maybe if I ever have an electric car that is not Tesla I will be happy I have the Emporia??

How is your home electrical infrastructure set up?

You have the utility meter... and from there it feeds the lugs of a single load center for your house? Does your solar simply backfeed your main home load center through a circuit breaker? Do you have a single Emporia Vue V2 clamped to the main lugs of this load center?

I was on a chat with their support today to learn a bit more about how their fancy EV charger would work. The rep said I'd need a stand-alone VUE clamped to the 200A main lugs on the load side of the meter. So this particular Vue would detect any possible backfeeding to the grid, and this Vue would be the one to trigger their EV charger to ramp up/down the EV charging load.

I have 2 other Vue's already installed on two separate sub-panels in my house. So if I did the fancy EV charger, I'd have to get a 3rd Vue and put its main lug CTs somewhere right after the meter.

Edit: The chat guy anecdotally said that Emporia's developers first tested this with a Tesla, since that's what the devs drive. He could be blowing smoke, but he insisted this Emporia EV charger solar-load-thing should work with a Tesla.

 

[holeydonut]

Now that I'm on solar with NEM2, I believe I'll be paying "non-bypassable charges" when charging at night using power generated during the day. These are small, but they add up - I'm calculating about $180 a year for 25,000 miles.

One way to avoid this is to charge during the day and constantly adjust the charging rate to match the solar generation. But that's a lot of work, so I've been looking for a "set and forget" solution.

There are some EV chargers (e.g. from Emporia, Wallbox, and probably others) that can supposedly charge a car using the excess power that would otherwise be sent to the grid. They do this by measuring the output through the electric main or communicating with a PG&E Smart Meter and adjusting the power delivered through the EV charger to keep the net exported power at around zero.

These seem like they would save money (by avoiding non-bypassable charges), and they'd also avoid using/straining the grid (which proponents of "NEM3" claim is a big deal that needs to be paid for).

Does anyone have experiences with these types of chargers or this type of charging strategy?

If grid usage is such a big deal (see discussion about NEM3), I also wonder why this this charging strategy isn't promoted more, and why there aren't incentives to install them.

Who installed your solar? If it's Tesla and your EV is a Tesla, you should check out ChargeHQ (it's currently beta). It will read your Tesla API, and instruct the car (on refresh per minute) to charge based on whatever your solar production is less whatever your home is using. You do NOT need a Tesla Wall Charger or HPWC.

Here the app working as intended... the overall hump/curve is my solar production. Early in the day, solar charges my powerwalls (green). Once the powerwalls are full, chargeHQ tells the Model 3 to charge. So the total sum of the charging + home loads equals (in blue) the solar production.

This way... very little goes to the grid. This is the "grid graph". Overnight and in the morning while my Powerwalls were charging, my home is using grid energy. Powerwalls can only be solar-charged which is why I prioritize getting them full ASAP. Once the Powerwalls are full, you can see the grid import/export goes to nearly zero while the ChargeHQ attempts to soak up everything with the EV battery. And to your point, saving on NBCs.

And once the EV is full, the solar has nowhere to go and hits the Grid. Resulting in NBC's

Here's a spot-photo of one single minute interval... You can see how the car charging is the reason my total home loads matches my solar production.

It's beta, and I'm having some other weird things (my solar isn't actually from Tesla, I just have the Tesla interface because of the Powerwalls). But maybe you'll have better experience than me.

 

[israndy]

I wrote a Python Script called TesSense, it could be re-written for any energy monitor, but it's intended to use a Sense Energy Monitor to determine the free solar generation, it then tells your Tesla directly, so you can use ANY charger, how much charge to take at the moment. It's free (after you purchase the Sense) and I am around if you have questions. It runs in a terminal window on any machine that has Python3 installed.

 

[Tazzman]

How is your home electrical infrastructure set up?

You have the utility meter... and from there it feeds the lugs of a single load center for your house? Does your solar simply backfeed your main home load center through a circuit breaker? Do you have a single Emporia Vue V2 clamped to the main lugs of this load center?

Yes my setup is basically how you describe there. I have ct's on the solar that feeds the panel so it can see the solar being produced then the main ct's that are before the main breaker can see how much is being sent to the grid. I'm not a programmer but it does not make sense to me why this is difficult for them to get working properly it should be a simple math equation that spits out a number to charge at but it just doesn't work. They also told me they tested with a Tesla but to me that is irrelevant since the charger sets the charge rate and car just takes what is supplied.

 

[Tazzman]

I wrote a Python Script called TesSense, it could be re-written for any energy monitor, but it's intended to use a Sense Energy Monitor to determine the free solar generation, it then tells your Tesla directly, so you can use ANY charger, how much charge to take at the moment. It's free (after you purchase the Sense) and I am around if you have questions. It runs in a terminal window on any machine that has Python3 installed.

That looks good. I know production and consumption can be pulled from the Enphas Envoy on the local network it's just to bad I have no clue how to write a program for it.