Using model S to power home

Using model S to power home

Most of the time my car sits in the garage. I only use it when I have to go somewhere. Is there some way I can use my model S to power my home at night and charge it during the day with solar panels? I guess I would have to remember to plug and unplug my charging cable each time I used my car.

Nexxus | 9 April, 2018

No. No V2G ties exist from the Model S to the house. This has been discussed, ad nauseum, here. | 9 April, 2018

I'll also add that you're usually best off charging the car late night, and using the solar to feed the grid. It depends a lot on your electrical rates. We have a Time-of-day plan where we get more money for the solar power during the day - feed back into the grid, and it costs very little to charge between midnight and 6am. Unless you have a massive solar array, usually the charging will consume more power than the solar array puts out (per hour). There is some flexibility to the car's charging rate, but it's not clear cut until you understand your specific situation (electrica rate plans, solar output, and how much your solar array puts out, and if you're home during the day).

Tesla allows you to set what times the charging should start, so it's easy to have it start charging at midnight when the rates are lowest.

Should_I | 9 April, 2018

Why would Tesla allow you to put the extra wear and tear on the warrantied battery? Especially when they sell a power wall meant to do this.

reed_lewis | 9 April, 2018

Exactly @Should_I! Tesla makes a power wall which is designed to be used in a home for backup and storage of power in a house environment. Imagine if the car were to be not there or discharged when the power goes out? Then you have no power. Plus most people work during the day. The car will not be there anyways.

T35LA | 9 April, 2018

I always use my car when I have to go somewhere ;-)

reed_lewis | 10 April, 2018

@T35LA - Actually it would be more correct to say that whenever I take my car, I am going somewhere. Sometimes I go somewhere but do not take the car because someone has picked me up or the like.

But either way, you are correct. When the car is gone, you are typically gone also!

Blueskies | 10 April, 2018

I'd like to see a new tax incentive for cars with grid capability for the first 200,000 cars that let users decide how much of the battery charge can help power the house or offset the duck curve. I'd gladly give up free supercharging and accept a reasonable reduced, use-based battery warranty penalty. What better way to help accelerate Elon's transition to renewable energy? I took delivery of my Tesla X in March and plan to get solar installed in June.

This could be another option Tesla would charge owners to activate like AP, SD, or when they limited 75 KW hardware batteries to 60 KW, and a great way to incentivize potential customers to buy a Tesla in the first place.

SUN 2 DRV | 10 April, 2018

"I'd gladly give up free supercharging and accept a reasonable reduced, use-based battery warranty penalty. What better way to help accelerate Elon's transition to renewable energy?"

So just install a PowerWall, they are designed for that that purpose and they don't ever leave home and leave your family stranded without any backup energy.

A Powerwall doesn't make a good car and a car doesn't make a good powerwall. Each is tailored to best suit its purpose.

Vorg | 14 July, 2018

The case for seems fairly straightforward. What am I missing?

Use Tesla Vehicle Battery for Home Charging In Case of Power Failure

Quite simply enabling Tesla vehicle batteries for home charging in case of power failure would increase the value of Tesla cars and help improve public safety while potentially providing a source of additional revenues for Tesla

Arguments For:
- Public Safety: Provides an effective source for home heating / cooling in the case of power outages
- Value Add For Tesla Owner: Reduces need to purchase other home battery systems in case of power failure
- Advantages over PowerWall: Enables customer to refill at another location in case of power failure, doesn't take up additional space in home, much larger capacity

Arguments Against --> Remedies / Counterpoint
- Customer Overuse / Abuse: Customers would have an incentive to use free Superchargers to refill cars for use at home --> Set limits to the number of times a customer could refill and use for home use in a year
- Accelerates depletion of battery through greater non driving use --> Set limits / additional fees based on the number of times a customer could use for home use in a year
- Disadvantaged vs. PowerWall: PowerWall provides a constant source at home vs. the vehicle which may need to be used to commute --> Many customers have more than one car so could use the other car in times of power failure or call an uber, let the customer therefore make the decision if they want use a PowerWall or their car battery | 15 July, 2018

@Vorg - well reasoned. Now that Tesla can charge for Supercharger usage that covers one part of the puzzle. So those that elect for this option might not be allowed free Supercharger use.

There is additional hardware required in the home. You need a powerful inverter to convert the vehicles DC battery to two-phase 240 VAC. Then you need switchover circuitry in the breaker box to allocate lower-power circuits to the battery backup circuits and isolate the outside lines for safety. Typically power hogs like the range, oven, A/C and electric heating are not connected to emergency power. The cost for all this is at least $5K and possibly a lot more depending on the panel and wiring access.

May be well worth it to some, but the costs are not trivial. How to charge for excess battery usage becomes a bit more tricky, but perhaps each home discharge event reduces the battery warranty by 500 miles. The unlimited mile warranty would need to be tossed for the S/X.

My guess is given all the complications and costs, there would be few takers. Still I'd love the feature if not costly. I have maybe one or two power failures a year lasting under an hour. UPSs protect key gear, but having most of the house powered would be nice.

lilbean | 15 July, 2018


Yodrak. | 15 July, 2018

"two-phase 240 VAC"

Single phase (in the US anyway).

EVRider | 15 July, 2018

Whether or not Tesla could make it possible to use your car's battery as a backup power source, they would much rather sell you a Powerwall and have no incentive to do otherwise.

Yodrak. | 15 July, 2018

It is possible, but it will cost you your warranty.

lilbean | 15 July, 2018

Then people would use free supercharging to power their homes.

Yodrak. | 15 July, 2018

An inverter can be run off the 12 volt battery, the traction battery will keep the 12 volt battery charged. Will run essential items during a power outage, but I doubt will run a whole house routinely. Don't know what kind of damage would be done to the 12 volt battery after what period of time. In any case, one is not going to be able to go off the grid by driving back and forth to a supercharger.

A year or three back a guy made a really elegant inverter unit that mounted on top of the 12 volt battery in his Leaf. An impressive project

Vorg | 16 July, 2018 Thanks for the thoughtful response. Agree that I would love the feature also if less than $5k. Tesla should be able to figure this out and charge appropriately to curb any abuse. How do we get this on Elon's radar?

@EVRider. Tesla does have an incentive, they could charge an additional fee each time you power your house (or something similar)

@lilbean. Please reread the forum, solutions for curbing use of free supercharging is considered.

lilbean | 16 July, 2018

Reread the whole forum? That’s a lot of reading.

Vorg | 16 July, 2018

@lilbean. Cute, rereading this thread should suffice but feel free if you have the time ;).

mark | 10 August, 2018

With my EV TOU rates, I would love to load shift 20KWH daily from my Summer peak $.54 to $.09 super off peak rates. I usually never get below 40KWH remaining when I get home @5PM and peak rates (4-9PM) are in effect. EV2Grid sounds like a big opportunity to save the grid and put money in both Tesla and it's customer hands.

BTW, sounds like Model 3 production is crippling powerwall production. EV to grid would tap a lot more MWH if we could tap existing capacity.

vance4c | 7 January, 2020

This is an old discussion but I wanted to post this somewhere. Here is a company that is making bidirectional DC chargers for the home consumer. They do not have a Tesla version but we can always hope that they or Tesla makes one.

EVRider | 7 January, 2020

@vance4c: Electrek posted an article yesterday about that:

kaffine | 9 January, 2020

Now I wish I went to CES this year.

I would like to know if it can actually power the house if the grid is down. It is going to be harder to do that than to supply power to the grid. It is possible but makes the install a lot more complicated as it can't simply backfeed the breaker like it can if it is supplying power to the grid when the power is on.

reed_lewis | 9 January, 2020

@kaffine - Actually it is quite easy to power a house when the grid is down as long as there is some sort of switch where the power comes into the house. You are correct that it is more complicated, but it is a pretty simple switch that gets installed between the meter and the house.

I have powerwalls, and Tesla installs a backup gateway that turns off the grid connection when it senses that there is no power coming from the grid.

kaffine | 9 January, 2020

Makes the install a lot harder. Of course part of the issue is how they do power meters/ panels here. Either way I need to get a journeyman's license before I can install it. Last time I checked grid interconnection required a licensed electrician all other electrical work I can do myself without a license (on my own home).

The other thing is if it is considered an automatic backup then it either has to be able to power the entire house or you need a sub panel of the loads you want backed up. That isn't a requirement for manual as they assume you can just flip breakers yourself.

ivandenis011 | 9 January, 2020

I agreed. It is infact quick and easy to accelerate when grid is down. I got though a little difficulty in switching between meter and the house but i got good advice from here