How to charge powerwalls from grid with solar

[swedge]

coney27,

I am sorry to contradict what everyone else believes, but if you are willing to use the installer "wizard" menu, there is a way. It is a bit of a hack, but no wiring changes, only standard gateway interface and app settings changed.

In fact, yesterday, I did exactly what the original poster wants to do. I have solar and one PowerWall, in northern Calif, PG&E, EV2-A rate, NEM1.

It was foggy in the morning, and I was not getting enough charge to get me through the peak period, 3PM through midnight. So, at 1:30 pm I enabled charge from grid for just over an hour to top up the PowerWall. I used the method I described in my October 17 post to this form.

PowerWall w/ Solar, Charge From Grid Experiment

Basically I used the local web interface and logged in as Installer, re-configured the CT's 3 and 4 to be Site, rather than solar, and then in the Tesla app set the PW to Backup Only. Bingo, 3.3 kW of charge. When it reached 100% I restored the solar configuration and time-based mode.

Kind of a pain, but it works. In this scree shot you can see grid charging from ~1:30 to ~2:30, and the the PW picking up the load from 3 till midnight.

 

[BrettS]

One thing to note is that your hack will screw up the tallies for your solar production. It will not record any solar production during the time you have your solar CT’s configured as site instead of solar and there will be no way to recover this data. Your daily, monthly, annual, and lifetime solar production and impact stats as shown in the app will no longer be accurate. Obviously doing this once for an hour will probably be imperceptible in the lifetime stats, but if you do it regularly it could make a noticeable difference.

And I’m sure this is something that would bother some people more than others. But it’s worth pointing out so people know what they’re getting into if they attempt this.

 

[swedge]

One thing to note is that your hack will screw up the tallies for your solar production. ...

And I’m sure this is something that would bother some people more than others. But it’s worth pointing out so people know what they’re getting into if they attempt this.

Brett,

True on both counts!

Not only is the solar not logged, but it is added to what is actually drawn from the gird, so the grid draw numbers won't match what the utility meter reports. In my case, my Enphase system has it's own data collection, so I am not loosing any data.

And, like I said in my post about the experiment, I do not recommend this. Note also however, that I don't recommend against it either, for those who don't mind learning about their systems.

It sure would be nice if Tesla included charge from grid functionality and appropriate time based modes. It would help us stay off grid during peak time, saving us money and reducing PG&E peak load.

I passed on federal income tax credit on the battery, so Uncle Sam is OK with it. PG&E clearly does not allow discharging to the grid, but time shifting is what the PUC's SGIP is all about, whether PG&E likes it or not.

SW

 

[h2ofun]

coney27,

I am sorry to contradict what everyone else believes, but if you are willing to use the installer "wizard" menu, there is a way. It is a bit of a hack, but no wiring changes, only standard gateway interface and app settings changed.

In fact, yesterday, I did exactly what the original poster wants to do. I have solar and one PowerWall, in northern Calif, PG&E, EV2-A rate, NEM1.

It was foggy in the morning, and I was not getting enough charge to get me through the peak period, 3PM through midnight. So, at 1:30 pm I enabled charge from grid for just over an hour to top up the PowerWall. I used the method I described in my October 17 post to this form.

PowerWall w/ Solar, Charge From Grid Experiment

Basically I used the local web interface and logged in as Installer, re-configured the CT's 3 and 4 to be Site, rather than solar, and then in the Tesla app set the PW to Backup Only. Bingo, 3.3 kW of charge. When it reached 100% I restored the solar configuration and time-based mode.

Kind of a pain, but it works. In this scree shot you can see grid charging from ~1:30 to ~2:30, and the the PW picking up the load from 3 till midnight.


View attachment 608580

Very cool stuff. Have a link to a installer interface tread? Have not been able to find. Thanks

 

[wwhitney]

Not only is the solar not logged, but it is added to what is actually drawn from the gird, so the grid draw numbers won't match what the utility meter reports. In my case, my Enphase system has it's own data collection, so I am not loosing any data.

I would think disabling the Solar CTs (choosing None) would give you accurate grid numbers. The "Home" number should end up as Consumption - Solar.

Cheers, Wayne

 

[swedge]

I would think disabling the Solar CTs (choosing None) would give you accurate grid numbers. The "Home" number should end up as Consumption - Solar.

Cheers, Wayne

Wayne,

I think you are right, however I have not tried that. I worried that a non-zero number from a CT configured as non-extisting might throw an error, while it seems to tolerate two grid-like sources just fine.

Just to put the idea of grid charging to avoid TOU peak prices into perspective, compare a normal day with a bad day to see how much one might save by grid charging. On a good day, Solar fully charges the battery, and during the peak period I drain it to around 40%. Worst case would be if I had zero solar production and used the full equivalent of 80% (I have reserve set to 20%) of the battery's capability, it would cost me around $1.70 per day extra. Yesterday grid charging saved me maybe 50 cents at most. Here in Calif, bad days seldom happen, so it may not be worth the attention and effort. Snow blacking out the panels for months on end, as our Original Poster may face, could be a different story.

I do wish that Tesla would give us the option to grid charge.

SW

 

[jjrandorin]

coney27,

I am sorry to contradict what everyone else believes, but if you are willing to use the installer "wizard" menu, there is a way. It is a bit of a hack, but no wiring changes, only standard gateway interface and app settings changed.

In fact, yesterday, I did exactly what the original poster wants to do. I have solar and one PowerWall, in northern Calif, PG&E, EV2-A rate, NEM1.

It was foggy in the morning, and I was not getting enough charge to get me through the peak period, 3PM through midnight. So, at 1:30 pm I enabled charge from grid for just over an hour to top up the PowerWall. I used the method I described in my October 17 post to this form.

PowerWall w/ Solar, Charge From Grid Experiment

Basically I used the local web interface and logged in as Installer, re-configured the CT's 3 and 4 to be Site, rather than solar, and then in the Tesla app set the PW to Backup Only. Bingo, 3.3 kW of charge. When it reached 100% I restored the solar configuration and time-based mode.

Kind of a pain, but it works. In this scree shot you can see grid charging from ~1:30 to ~2:30, and the the PW picking up the load from 3 till midnight.


View attachment 608580

its interesting to me that this is "possible" but I wouldnt personally do this. The reason is, I suspect that any logins to the installer interface are likely logged (if they arent they absolutely should be.. would be surprising if they arent) and I wouldnt want anything at all getting in the way of any possible warranty claim.

Saying that, however, I believe its very informative that its "possible" if one is willing to mess around with the installer interface. In an emergency situation, that might be useful.

Thanks for sharing the information!

Edit: I should say (for qualification purposes) I am pretty risk averse when it comes to things like this. I mention this so that anyone reading knows where I am coming from when I say "I wouldnt do it". That doesnt mean I dont think anyone should or should not do it, just that "I" wouldnt... but I am risk averse as I said.

 

[Ribeyesteak]

It is easy to grid charge. Don't get a PW... other batteries allow you to grid charge during super off peak.

 

[swedge]

Ribeye,

The original poster, myself, and many others on this thread already have PowerWalls, and would like Tesla to facilitate charging from the grid when it is legal to do so, not just during Storm Watch. But you do make a good point that lack of this feature is a competitive disadvantage for Tesla.

However, I have been setting my PW to charge from the grid on cloudy days since I posted how to do so in Oct 2020. It takes about a minute to change the settings back and forth in the Installation Wizard. This allows us to use grid power only during off-peak periods, even on cloudy days when our solar production is not adequate to sufficiently recharge the PowerWall.

 

[h2ofun]

Ribeye,

The original poster, myself, and many others on this thread already have PowerWalls, and would like Tesla to facilitate charging from the grid when it is legal to do so, not just during Storm Watch. But you do make a good point that lack of this feature is a competitive disadvantage for Tesla.

However, I have been setting my PW to charge from the grid on cloudy days since I posted how to do so in Oct 2020. It takes about a minute to change the settings back and forth in the Installation Wizard. This allows us to use grid power only during off-peak periods, even on cloudy days when our solar production is not adequate to sufficiently recharge the PowerWall.

I just sent you a PM

 

[Laketime]

It is easy to grid charge. Don't get a PW... other batteries allow you to grid charge during super off peak.

The main difference is with those batteries you can't claim them as part of your solar system for the federal tax credit.

 

[drmanny3]

I commend your efforts in energy independence. I have recently added two PowerWall2 batteries to our Solar Panels. So we should be covered in the case of a power outage. I have a question about charging your batteries. I want to be able to charge my batteries during the evening hours when electricity from the grid is the least expensive. However, the software from Tesla does not allow this. The best I can do is charge my batteries when the sun comes up. Any luck in doing differently? As for electric cars we have had 4, 2011 Leaf, 2014 Toyota Rav4EV, 2015 Kia Soul EV, 2017 Chevy Bolt. In addition 2 Toyota Prius vehicles, Toyota Highlander Hybrid, and currently in the garage is a Volvo XC90 T8 Plugin and an Acura 2017 NSX Hybrid. Keep up the good work.

 

[jjrandorin]

I commend your efforts in energy independence. I have recently added two PowerWall2 batteries to our Solar Panels. So we should be covered in the case of a power outage. I have a question about charging your batteries. I want to be able to charge my batteries during the evening hours when electricity from the grid is the least expensive. However, the software from Tesla does not allow this. The best I can do is charge my batteries when the sun comes up. Any luck in doing differently? As for electric cars we have had 4, 2011 Leaf, 2014 Toyota Rav4EV, 2015 Kia Soul EV, 2017 Chevy Bolt. In addition 2 Toyota Prius vehicles, Toyota Highlander Hybrid, and currently in the garage is a Volvo XC90 T8 Plugin and an Acura 2017 NSX Hybrid. Keep up the good work.

Hi, So as to not to dilute this OPs thread on their 10 powerwall solution, you can take a look at one of the "charge from the grid" threads. The TL ; DR version is, it sounds like there is a way to do this if you play with the installer interface and change stuff end users are not supposed to access. Please read the following thread, and direct any further questions on that topic to that thread instead of this one.

How to charge powerwalls from grid with solar

 

[Paul_G]

I commend your efforts in energy independence. I have recently added two PowerWall2 batteries to our Solar Panels. So we should be covered in the case of a power outage. I have a question about charging your batteries. I want to be able to charge my batteries during the evening hours when electricity from the grid is the least expensive. However, the software from Tesla does not allow this. The best I can do is charge my batteries when the sun comes up. Any luck in doing differently? As for electric cars we have had 4, 2011 Leaf, 2014 Toyota Rav4EV, 2015 Kia Soul EV, 2017 Chevy Bolt. In addition 2 Toyota Prius vehicles, Toyota Highlander Hybrid, and currently in the garage is a Volvo XC90 T8 Plugin and an Acura 2017 NSX Hybrid. Keep up the good work.

The software does allow this, but I think the way your tax rebates work for electricity in the US prevent this. In the UK I have a Powerwall and 4.4kw PV setup, and source my grid electricity from Tesla via Octopus energy. When you sign up to this plan, you buy and sell electricity at the same rate - GBP 0.08 per kWh. At about 1am UK time Tesla start charging my battery, typically to about 75%. Then depending on the weather, it either tops up to 100% during daylight hours, or takes a drip feed from the grid - my PV setup will run the house and all electrical except a kettle, toaster, oven etc even in overcast conditions. So based on weather the house runs on solar or grid during the day.

Then, at 4pm - peak time, Tesla start exporting power from the battery back to the grid for a couple of hours, until the battery discharges to. 20% - which is reserved for power outages.

The flat buy/sell rate means the charging / discharging costs me nothing, but allows Tesla to store energy in my Powerwall when wholesale rates are low, and then export when they are high. Come summer, when we get longer daylight hours, I should be able to charge up the Powerwall more from solar than grid, so may be a net exporter during the summer.

 

[BGbreeder]

I think that what @Jason Bloomberg has built is amazing. I applaud what you have achieved. Very thoroughly thought through, executed in stages to learn and modify the execution, all within what sounds like a less than ideal set of state laws.

@Paul_G I think that what you are doing is great for the stability of the UK grid, but there may be other issues at play for buyer/owners in other countries.

E.g. isn't the UK average total outage time about thirty five minutes per year? Customer interruptions and minutes lost: Electricity distribution (RIIO-ED1)

Different kettle of fish in the US, where it is closer to two hours, not including weather events, which are the bulk of the US downtime.
Average frequency and duration of electric distribution outages vary by states - Today in Energy - U.S. Energy Information Administration (EIA)

Many US owners are trying for backup reliability, and have to backup all phases, and for indefinite time periods.

Definitely YMMV in my book...

All the best,

BG

 

[Ribeyesteak]

The main difference is with those batteries you can't claim them as part of your solar system for the federal tax credit.

There is a way around it but it is considered "unethical."

 

[Laketime]

There is a way around it but it is considered "unethical."

There are ways around many laws. Pay cash, save the tax is one- that is another. How far down the rabbit hole some people go varies. It may also void your warranty if Tesla so desires.

 

[holeydonut]

I dunno if this was already posted, but I just found this little nugget in the Tesla Powerwall "Utility Interconnection" manual. It describes an experimental load-shifting option where the Powerwall will charge with off-peak energy so a homeowner has a healthy amount of suds to power through a peak time. I hope they build in a weather forecast option as well so that if the next day looks cloudy, then the reserve is increased to offset the expected drop in production.

Also, if this setting comes out, I hope people in the PG&E coverage area check the second box of their NEM-MT Appendix I agreement.

http://azmag.gov/Portals/0/Document...y_Documentation.pdf?ver=2018-02-22-161139-873

 

[jjrandorin]

I dunno if this was already posted, but I just found this little nugget in the Tesla Powerwall "Utility Interconnection" manual. It describes an experimental load-shifting option where the Powerwall will charge with off-peak energy so a homeowner has a healthy amount of suds to power through a peak time. I hope they build in a weather forecast option as well so that if the next day looks cloudy, then the reserve is increased to offset the expected drop in production.

Also, if this setting comes out, I hope people in the PG&E coverage area check the second box of their NEM-MT Appendix I agreement.

http://azmag.gov/Portals/0/Documents/MagContent/Tesla_Powerwall 2_AC_Utility_Documentation.pdf?ver=2018-02-22-161139-873

View attachment 637884

Does this mention anywhere that it would be enabled, by tesla, with solar? I suspect that, this is a mode that would be enabled for those without solar. I dont have any proof, but that is what would make sense given current restrictions tesla puts in place.

 

[Shopaholic]

Hi all,
I am new to solar, having gotten a new install last week- 8 kW with one PW. The panels are not turned on. However, when the team installed, the Power-wall got charged to 100% from the grid and last 2 days, it’s used up about 45% for peak time flow to the house. The “ storm watch” icon is flashing but the powerwall did not get recharged back up to 100%? Will this happen only after solar is working?