powerwall2 behavior when paired with solar

[solardreamer]

this is true - i know there are/were guys on the old prius yahoogroup that would do this with a gen2 prius. however even at 1200W you'd be calling for 100A on the 12V side... can you really pull that much current from the 12V system on a bolt without blowing a fuse somewhere in the car?

also nissan had demoed whole-home backup with a home inverter plugged into a leaf but i don't know if that went anywhere... it might have just been a prototype.

Many people have successfully done this to get through natural disasters just check the EV forums. EV DC-DC converters are typically rated for 120A-150A with some (e.g. Tesla) up to 250A so it's definitely enough for essential backup power needs. The converters usually have a fuse but like any battery inverter system you should put in your own fuse.

As for Nissan V2G/V2H, I have been waiting for years now since they talked about it 5+ years ago. I remember reading DOE/DARPA have also funded several V2G projects over the last decade but no generally available products. The main issue is that car companies still make much more profit from traditional ICE cars.

Given the relatively slow EV adoption, I think EV companies should make backup power a feature and selling point to help get more EV adoption. Just as the smart phones provided many more functions than just replacing the traditional cell phone function to get large volume adoption. EV's need to do more than just traditional ICE cars and half baked self-driving function is not it.

[Ampster]

Many people have successfully done this to get through natural disasters just check the EV forums. EV DC-DC converters are typically rated for 120A-150A with some (e.g. Tesla) up to 250A so it's definitely enough for essential backup power needs. The converters usually have a fuse but like any battery inverter system you should put in your own fuse.
...............

I don't think either of my Teslas have a 250 Amp rated auxiliary power outlet. The DC to DC converter may be rated at 250 Amps but I don't know where I would access that. I suppose I could clamp on to my 12 V battery terminals but it is fairly hard to get to and I have another source of backup power so I don't need to stress my motive power.

[astroboy]

I don't think either of my Teslas have a 250 Amp rated auxiliary power outlet. The DC to DC converter may be rated at 250 Amps but I don't know where I would access that. I suppose I could clamp on to my 12 V battery terminals but it is fairly hard to get to and I have another source of backup power so I don't need to stress my motive power.

right - the cigarette lighter probably has a 10A fuse or so but you can connect right to the battery. i was just reading this thread at one of the bolt forums:

https://www.chevybolt.org/threads/us...-backup.14986/

looks like the bolt is good for > 100A at the battery terminals (though there is some kind of current sense in series with the battery so i guess you're supposed to ground the inverter on the chassis.)

anyway this would be a stopgap for the PGE power shutoffs just to keep the refrigerator running. i have a gasoline generator but i really don't want to run that for extended periods nor do i have enough gasoline on hand to do that...

[solardreamer]

I don't think either of my Teslas have a 250 Amp rated auxiliary power outlet. The DC to DC converter may be rated at 250 Amps but I don't know where I would access that. I suppose I could clamp on to my 12 V battery terminals but it is fairly hard to get to and I have another source of backup power so I don't need to stress my motive power.

The cigarette lighter sockets are only good for 15A. You connect inverter to the 12V battery terminals. Not sure why you find it hard to access battery terminals. I don't remember any special difficulty on my Tesla or other EV's I owned (Chevy Spark EV, Mercedes B250e). I have seen people setup permanent battery cables with Anderson connectors for quick connect/disconnect. The frunk is perfect space for a small inverter. I have natural gas generator so EV would not be a primary backup power source for me either. However, it's a good and easy option to have.

[Ampster]

........ Not sure why you find it hard to access battery terminals. I don't remember any special difficulty on my Tesla or other EV's I owned (Chevy Spark EV, Mercedes B250e). I have seen people setup permanent battery cables with Anderson connectors for quick connect/disconnect. The frunk is perfect space for a small inverter. I have natural gas generator so EV would not be a primary backup power source for me either. However, it's a good and easy option to have.

The 12V battery in the MX is under the Frunk and I watched a ranger do a battery swap and it was a lot of screws. I haven't had the Model 3 long enough but I just might hook up some Anderson connectors to have a backup. That would be a good way to boot the car if the 12V died. I do have one of those 12V Lithium Jump starters because three the EVs I have had I have had the 12 V battery go dead. (RAV4EV, SmartED. and Fiat 500e. Those were very accessable. Never had it happen in the Tesla's though. The 12V swap out was because they could see the 12V battery was going bad and they proactively replaced it. Gotta love the online diagnostics.

[astroboy]

fresh off my first PSPS - 44 hours with no power.

it got real old setting up the generator each morning to run the fridge and freezer - didn't want to run it at night unattended. not being able to charge devices overnight was a hassle... and then trying to decipher whether or not PGE would get us up and running again before tuesday's new wind event was torture. i'm almost willing to pay whatever they are asking for a powerwall just to put this kind of crap behind me.

i did manage to get an inverter connected to my bolt, but it wouldn't drive the only load i cared about inside the garage - the water heater. the heater controller gave a "reverse polarity" error but now that i'm thinking about it i wonder if it was unhappy that there was no earth ground, rather than the inverter not putting out the right waveform or voltage. i'll have to experiment now that the power is back and there's not as much stress involved.

[JSchnee21]

During hurricane Sandy, we discovered our hot water heater (AO Smith Power Vent w/Electronic Control Board and Electric Igniter) was equally fussy. It would run off of my neighbors older, smaller generator but not my larger, shiny new one (both portable). It turns out it needed to have floating ground (I think I'm remembering right -- I had to remove the bonding leg on mine) AND it needed to be non-GFI else when the electronic igniter would try to start the natural gas, it would trip the GFI. After "correcting" these issues it now works fine. Bonded vs. non-bonded is a common issue -- lots of detail on various forums. The OSHA's recent (at that time) mandate for GFI on generators was fairly new.

Rewiring the furnace and dishwasher to use a plugs was also a small headache at the time when you're in the midst of it. It would get cold at night in October here, and with two small infants we had a lot of dishes, laundry, etc.

But, if you have natural gas, I'd strongly recommend looking into an 1800rpm Nat Gas generator instead. It's cheaper (to purchase and install-- though not to operate), and will give you unlimited run time. But if you think a battery storage solution can give you the runtime you're need, by all means.

Or at least get an external, manual transfer panel for your portable generator and an Autotransformer to balance the legs. Purchasing, running, and storing enough extension cords is a huge headache, speaking from personal experience, not to mention the trip hazard, fire hazard, and trying to find a way to close/seal and secure up the door crack(s) they pass through from outside

[JSchnee21]

A few other suggestions:

1) Invest in several large USB battery packs and keep them charged for unplanned outages. Use these to charge phones, hotspots, USB lighting, etc.

Battery
https://www.amazon.com/Anker-PowerCore-20100mAh-Portable-Delivery/dp/B071WNWRNC/ref=sr_1_5?keywords=anker+battery+pd&qid=157234756 7&sr=8-5

https://www.amazon.com/Anker-PowerCore-Portable-Capacity-PowerPort/dp/B01K6TA748/ref=sr_1_14?keywords=anker+battery+pd&qid=1572347605&smid=A294P4X9EWVXLJ&sr=8-14

Lights -- these are amazing, really bright. Runs for >6 hours on 10,000 mAh

https://www.amazon.com/gp/product/B0198VDWMY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Flashlight

https://www.amazon.com/gp/product/B01KH2JP5G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

2) Switch to a more reliable cellular operator -- AT&T or Verizon, or both which has UPS in place for emergency responders. Consider a dedicate cellular/Wifi hotspot for internet and phone access.

3) When Sandy hit, most people's home internet networks (Verizon FIOS and Comcast xFinity) were actually up and running. But folks couldn't use them as their house/Wifi had no power. Don't forget to run these off of your generator (or UPS) and check. This can be a real "lifesaver" if you have bored or scared kids with nothing to do (-: And iPad and a Cellular Hotspot or home internet will keep them out of your hair while you deal with real issues.

4) you probably won't have issues with water filtration. But lifestraws work wonders if you're concerned your local wasteplant was flooded or lost power

https://www.amazon.com/LifeStraw-Personal-Camping-Emergency-Preparedness/dp/B006QF3TW4/ref=sr_1_1_sspa?keywords=lifestraw&qid=1572347971&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyQURQQU9WTTcxVVlEJmVuY3J5cHRlZElkPUEwMDE3NDg4MVFTNzlTTVNKMEZVOSZlbmNyeXB0ZWRBZElkPUEwNTMyMDcwVFRDVVBPNlpSRUlEJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

[blueman2]

I just saw a note that Telsa is offering $1000 discount to those of us impacted by PGE PSPS. But I am sure they are already backed up 6+ months on installation.

[J.P.M.]

I just saw a note that Telsa is offering $1000 discount to those of us impacted by PGE PSPS. But I am sure they are already backed up 6+ months on installation.

I'd check and see if there was a price increase of $1K just before the discount appeared. It's just business.

[JSchnee21]

How many kWh do you typically use per day? Can two or three PowerWall2 sized batteries (or similar) really cover you for 2 to 3 days? (I have no idea how long such a power cut would be expected to last -- I was surprised when you said 44hours!) Especially if only charged by the Sun? Can the AC coupled PW2 get charged by the Sun while the grid is down? Isn't you're solar inverter also offline?

IMHO, I think PS&G is just doing this for show to get the regulators and state to say "Uncle" and draft some sort of "Act of God" indemnity legislation for them. Seriously, their best solution is to turn off power when it's dry and windy? That's such BS.

Of course that's no comfort to those who were impacted.

[blueman2]

“Apologies to those waiting for Solar/Powerwall outside California, as we are prioritizing those affected by wildfires,” Musk tweeted today.

[scrambler]

fresh off my first PSPS - 44 hours with no power.

i did manage to get an inverter connected to my bolt, but it wouldn't drive the only load i cared about inside the garage - the water heater. the heater controller gave a "reverse polarity" error but now that i'm thinking about it i wonder if it was unhappy that there was no earth ground, rather than the inverter not putting out the right waveform or voltage. i'll have to experiment now that the power is back and there's not as much stress involved.

I ran Two and an Half days off of our Chevy Volt Battery. I use a pure Sine wave 1500 / 3000 W inverter with a 100A breaker protection (you are not supposed to pull more than 1000W from the Volt through the 12 V battery). We were able to leave the Fridge, internet (as long as the service was up), the TV and some light on it the whole time, and recharging phones and laptop.


What I did learn was that my power strip would not work at first (it would only work directly connected to the inverter), then I realized I had not connected the Inverter Ground to the Car Ground. Once I did that, the power strip worked.

We were lucky to have a gas water heater that does not require any electricity.

[scrambler]

How many kWh do you typically use per day? Can two or three PowerWall2 sized batteries (or similar) really cover you for 2 to 3 days? (I have no idea how long such a power cut would be expected to last -- I was surprised when you said 44hours!) Especially if only charged by the Sun? Can the AC coupled PW2 get charged by the Sun while the grid is down? Isn't you're solar inverter also offline?

When a Powerwall (and gateway) is installed with Solar, it will enable a regular inverter to stay on during an outage to recharge the battery.
That is one of the benefits of the Powerwall for retrofit installations.

[astroboy]

too many replies to quote them all but -
JSchnee21: same water heater; the controller is indeed very finicky. from reading scrambler's post i think maybe i just need to ground the inverter to the bolt, however, i'm not sure this inverter has a ground lug. i have a much higher quality one on order, so maybe that has the right connections. as for your other tips as it turns out i have everything you have mentioned. i did use my spare UPS to charge things during the night, and then i found out that it would not charge from the generator. this may have had to do with grounding as well. regardless we were able to charge our stuff during the day using the generator but it requires breaking decades-long habits ("oh i can charge this phone overnight...")

as for the house, if no one is home (like on vacation) with just the refrigerator running and a subset of the computers, the house uses ~10kwh per day. i'm sure we could reduce that further. in theory then a single powerwall could keep us going for a day. at the winter solstice, assuming there is sunlight, my PV system will produce about 13kwh. so in the absence of clouds the PW would keep us going indefinitely. in practice we'd probably crap out eventually. my plan was for 2 powerwalls to get more current, and hopefully these PSPS things only happen in autumn when the system makes about 20kwh per day.

i have all of my network on UPS backup and when the power went out comcast's head end failed immediately. it's still down 12+h after power was restored. my ancient DSL backup stayed up during the outage but my UPSs are not big enough to run for more than a couple of hours, so we had to use our cellphones for internet access. they did work throughout, maybe because just down the hill the power was on and so parts of the cell network were still operating normally. i did hear that up in marin after a couple days many cell towers started dropping out.

as far as tesla goes, i don't know if "affected by wildfires" means "affected by PSPS" but who knows, maybe they'll knock 1k off my order. i'm not expecting them to get to it until 1Q2020 or maybe later.