Equipment for using an EV as a battery backup?

[GaryT]

I have a 12 year old, grid tied, 5kW microinverter, AC coupled solar array. Over the course of a year, the solar array generates a net positive amount of energy. It is also true during sunny daytimes, and my meter spins backwards. I am highly interested in purchasing a bi-directional EV to use as backup to power my house during a blackout. There are five announced EVs (Ford F150 and Volkswagen ID.4 with possible deliveries in 2022.) Plus announced bi-directional chargers with deliveries later this year. (Dcbel, Quarsar_2, Ford Charger station Pro). Does anyone have any insight as what equipment is needed to make this a working island solution? I am expecting to remodel my main panel to make it future proof for all electric heat pump appliances.

1) I know I need a disconnect switch from the grid. What is the smallest 200amp disconnect switch? I am somewhat space constrained. If possible, I would like to power my main panel and shed loads manually. Since I do not want solar vendor batteries, or a permanently installed generator, those vendors decline to engage in discussions.

2) The Dcbel is DC coupled to the solar array. It will not fit my need. Quasar_2 bi-directional charger is AC coupled. So, it is getting close. Ford charger unknown. Does anyone know if those chargers provide "islanding" control? If the batteries are full, and the loads in my house do not consume all the solar power, the AC phase has to be shifted to detune, and/or turn off the solar panels. For example, some off-grid, hybrid AC invertors have this function. But getting too many boxes to work together seems complicated.

I could get a 2000w external AC inverter and connect it to the 12V DC cabin system on the EV and connect it to the refrigerator, but that is a minimal solution as it does not take advantage of the solar array. Does anyone have more insight or suggestions?

Thank you

[solardreamer]

What you want is not generally available yet. I remember seeing a company or two working on it. I can dig them up if you are interested in pursuing such emerging solutions.

Frankly, I am skeptical about the DC bidirectional chargers at this time because the actual standard for CCS bidirectional power transfer will not be finalized until 2025 at the earliest so I expect many EV/charger interoperability issues before then. The only exception maybe Ford since they will provide both EV and charger.

I see EV's with built-in V2H (e.g. Ford F150, Hyundai Ioniq 5) or similar add-on's as more realistic in the near term.

[SunEagle]

What you want is not generally available yet. I remember seeing a company or two working on it. I can dig them up if you are interested in pursuing such emerging solutions.

Frankly, I am skeptical about the DC bidirectional chargers at this time because the actual standard for CCS bidirectional power transfer will not be finalized until 2025 at the earliest so I expect many EV/charger interoperability issues before then. The only exception maybe Ford since they will provide both EV and charger.

I see EV's with built-in V2H (e.g. Ford F150, Hyundai Ioniq 5) or similar add-on's as more realistic in the near term.

I am curious about that type of hardware also since I had heard CA was going to use people's EV batteries to reduce production demand if they were being charged at a home. Has that ability ever been moved forward?

[scrambler]

Most of the new EV (Hyundai, Kia, Ford pickup...) seem to finally come with a bidirectional charger and EVSE, so that the Charge port can both accept power and provide power.

Some will actually offer a Transfer switch installation option for a complete setup.

But to do that right with enough power for the whole house, it needs to be built in the EV charger and the EVSE.

Without that, all you can do is add your own inverter to the 12V battery like a lot of us did with the Chevy Volt in the old days

[DanS26]

Let's just look at a couple of number here....the average American home uses ~1200kWh per month or ~40kWh a day. EV batteries on the high end vehicles can hold ~70 to 100kWh power. Now considering the battery reserve which can't be touched and the conversion losses DC to AC and maybe those vehicles could power an average house for about a day and a half.......maybe.

Pretty much a marketing gimmick and an expensive one at that.......these capabilities need full disclosure or else many average consumers are going to be mighty disappointed.

[SunEagle]

Let's just look at a couple of number here....the average American home uses ~1200kWh per month or ~40kWh a day. EV batteries on the high end vehicles can hold ~70 to 100kWh power. Now considering the battery reserve which can't be touched and the conversion losses DC to AC and maybe those vehicles could power an average house for about a day and a half.......maybe.

Pretty much a marketing gimmick and an expensive one at that.......these capabilities need full disclosure or else many average consumers are going to be mighty disappointed.

You also just justified why a small battery system will barely keep a house running more than a day or so. Especially if the reason the grid went down was due to bad weather and clouds.

[scrambler]

You can skew the number anyway that suits you, but the reality is that:

• Not every home use 40kWh per day, my average is 25kWh
• During an outage you would be conservative of energy limiting yourself to important loads.
• Most homeowners who invest in a Hybrid inverter with a solar battery today get 13 to 25 kWh of battery.
• With my 13kWh solar battery, powering critical loads, I can easily last 2 or 3 days without solar recharge during the day, and indefinitely with solar recharge.
• These cars can provide 4 times as much!

So I say having the ability to power your home with your electric car is anything but a gimmick for a lot of people

[SunEagle]

You can skew the number anyway that suits you, but the reality is that:

• Not every home use 40kWh per day, my average is 25kWh
• During an outage you would be conservative of energy limiting yourself to important loads.
• Most homeowners who invest in a Hybrid inverter with a solar battery today get 13 to 25 kWh of battery.
• With my 13kWh solar battery, powering critical loads, I can easily last 2 or 3 days without solar recharge during the day, and indefinitely with solar recharge.
• These cars can provide 4 times as much!

So I say having the ability to power your home with your electric car is anything but a gimmick for a lot of people

Great. Then why haven't the electric car manufacturers made the V2H a standard feature on their chargers?

Oh and most people I know use more than 40kWh a day but then again they have AC and pool pumps.

[J.P.M.]

You can skew the number anyway that suits you, but the reality is that:

• Not every home use 40kWh per day, my average is 25kWh
• During an outage you would be conservative of energy limiting yourself to important loads.
• Most homeowners who invest in a Hybrid inverter with a solar battery today get 13 to 25 kWh of battery.
• With my 13kWh solar battery, powering critical loads, I can easily last 2 or 3 days without solar recharge during the day, and indefinitely with solar recharge.
• These cars can provide 4 times as much!

So I say having the ability to power your home with your electric car is anything but a gimmick for a lot of people

If the product is sold with straight information that's understandable to the average homeowner, that product feature can be useful.

+1.
Critical loads during a power outage need to be determined beforehand and decisions made, but with some thought and planning, such critical load levels can be and usually are quite a bit less than average daily use. 40 kWh/day may be an emergency load scenario for some, but I'd guess 5 to maybe 10 kWh/24 hr. period at the high end many be survivable. I'd need about 3 kWh/24 hrs. and live to tell the tale. You can't live like a king in an emergency.

[DanS26]

Most people do not know the difference between a kWh and a hole in the ground......we're talking about average Americans here.....

[J.P.M.]

Most people do not know the difference between a kWh and a hole in the ground.......

Yea, the world is full of those types. Some of them show up here and get pissed when they are called on their ignorance and arrogance.

If you're addressing that to me, you're preaching to the choir.

On storage sizes/schemes for power outages/emergencies: Those who want no changes in their lifestyle can expect to pay more to meet their perceived needs and the lifestyle those needs entail.

For those with one eyeball and one balloon knot who are willing to use their head for something more than a hatrack, better/cheaper/faster/easier solutions are available.

Pay your money. Take your choice.

[solardreamer]

Most people do not know the difference between a kWh and a hole in the ground......we're talking about average Americans here.....

Do you use 40Kwh/day during blackouts? If so, how?

Seems very unusual.

[SunEagle]

Do you use 40Kwh/day during blackouts? If so, how?

Seems very unusual.

Still 40kWh a day is less then 2kWh / hour. So unless you have very efficient loads or turn off everything that is not needed (by the way AC is required during the summer months here) you might get below that 40kWh.

It really comes down to comfort for the family and where you live. If you need heat or AC then you will use a large portion of that 40kWh. If you have an older water heater it tends to consume power all night long and unless you have eliminated all of your vampire loads the kWh usage adds up.

[scrambler]

Great. Then why haven't the electric car manufacturers made the V2H a standard feature on their chargers?
.

Recently they all have started to. Hyundai Ioniq5, Kia, Ford...
It is recent, but it seems manufacturer are starting to understand that there is value in doing it.

[SunEagle]

Recently they all have started to. Hyundai Ioniq5, Kia, Ford...
It is recent, but it seems manufacturer are starting to understand that there is value in doing it.

OK. I guess I need to pay more attention to EV equipment although I am still waiting on an EV truck because that would be my next vehicle.