Powering Home with Electric Vehicle … Not Quite Yet!

7 min readSep 1, 2021

Electric Vehicle (EV) as an emergency power supply for home

In the U.S., recent blackout events dramatically impacted the daily activities of the public, including the tornado outbreak in April 2020, leaving 4.3 million customers without power; and the Texas blackout in February 2021, where four million Texans experienced a power failure. In extreme weather conditions, standalone battery systems can be critical for community survival and resilience.

Using the EV battery to provide electricity to homes has entered the public view of North America in recent years. The concept, however, has been being implemented in Japan for decades. During the 2011 Tohoku earthquake and tsunami, 66 Nissan Leafs supported the north-eastern coast of Japan for days as a primary power source.

On average, electric car batteries have 60 kWh capacity, which is approximately the equivalent of two days’ electricity consumption for the average American household. As an EV owner, you may have experienced using your car battery to provide emergency backup power to your household and started to wonder, “Can I use a vehicle battery as a home battery on daily basis?” Unfortunately, no, at least not yet; a household energy storage system is still required to do the work. Even though there are a few manufacturers that do support vehicle-to-home (V2H) technology, the vast majority of EVs in the marketplace have not included this capability in their products.

Why can’t I use a regular vehicle battery to charge my home?

For a regular battery, there are three main reasons to be taken into consideration:

1. Battery Lifespan

Extra demands can lead to the degradation of batteries and limit their lifespan. Factors such as temperature (hot temperature can lead to faster decline), how much and how often the battery is discharged, the type of charge, and the depth of discharge can all impact the state of health of the battery. Overall, the EV battery lifespan will be compromised with frequent charging cycles, and the cost of the battery degradation can greatly overweigh the gained benefits.

2. Cost of Battery Degradation

Let’s bring three factors into the calculation: cost per kWh, cycles, and efficiency.

According to a recent journal article on the cost breakdown of a battery electric vehicle (BEV), the battery takes up 39.40% of the whole cost of the BEV. An average cost of an electric vehicle is $55,600, hence, the average cost of a vehicle battery = $55,600 x 39.40% = $21,906.

*Note that the cost of electric vehicles in this article does not include incentives at the federal and provincial levels.

The typical coverage of a battery is a least eight years or 100,000 miles. A user often charges the electric vehicle two to five times a week. The current capacity of electric vehicles on the market ranges from 28.9 kWh in the Mini Cooper SE to 200kWh in the 2022 GMC Hummer EV. This article uses 75kWh to capture the commonly used battery capacity.

Take charging frequency of twice a week as an example,

the estimation of overall capacity during a battery’s lifespan:

= overall charging cycles x battery capacity

= (Twice per week x 52 weeks per year x 8 years) x 75kWh

= 832 charging cycles x 75kWh

= 62,400 kWh

The cost of battery degradation per kWh during the battery’s lifespan:

= Cost of EV battery per kWh

= (Price of electric vehicle battery / charging cycles)

= $21,906 / 62,400 kWh

= $0.35/kWh

Our estimation indicates that for each charging cycle, the cost of battery degradation per kWh will be $0.35/kWh.

In other words, when taken the price of the whole vehicle into account, the cost of EV degradation can be as high as $0.35 ÷ 39.40% = $ 0. 89/kWh.

The calculations of other charging frequencies follow the same steps, and the corresponding results are shown in the table below:

3. Availability

From a technical aspect, bi-directional charging is required to enable your car battery to be used as a power source, including an inverter to convert direct current (DC) from the battery to alternative current (AC) in the grid, and a battery management system (BMS) to monitor and operate the electricity flow.

Moreover, for grid-connected customers, it is difficult to align the schedule of use of electric vehicles within peak hours and household electricity to support daily activities. An electric vehicle for commuting purposes cannot satisfy the daily needs for household stationary charge and discharge.

Is there a way to get around this? Yes, through V2H and V2G technology.

What is Vehicle-to-Home (V2H) technology?

V2H technology works as follows:

During off-peak hours, the solar panel on your rooftop charges the electric vehicle battery or the electricity is drawn from the grid when the tariff is low. At peak hours, the battery will provide electricity for home consumption and support the functions of critical appliances in the home during a power outage.

Compared to V2H, the concept of Vehicle-to-Grid (V2G) is more broadly discussed. V2G’s emphasis is on providing electricity to the grid for the purpose of financial benefit rather than self-consumption. In addition to providing backup power and maintaining grid resilience, V2G can contribute to the stabilization of the grid. To make a profit, vehicle users can participate in the program and receive financial gains by providing ancillary services, such as demand response, fast frequency regulation, or peak shaving.

However, the most profitable method is being seen through energy arbitrage — purchasing and storing electricity at off-peak hours at a low rate and selling it back to the grid at peak hours when the cost is high.

Source: IRENA — International Renewable Energy Agency

Is Vehicle-to-Grid (V2G) technology cost-efficient?

Two examples are shown below to walk you through how to estimate the cost-efficiency of selling electricity to the grid through your electric vehicle. Based on our estimation above, the cost of electric vehicle degradation ranges from $ 0.36/kWh to $ 0.89/ kWh. Residential customers should compare the financial return with the cost to decide whether the number works in their favor.

The efficiency of a lithium-ion battery normally stays at 90%, which means that only 90% of the electricity input can be drawn out of the battery. In other words, when drawing electricity of 1 kWh from the grid, the battery is only able to use 1 kWh x 90% = 0.9 kWh.

Example 1

Sacramento Municipal Utility District (SMUD), one of the largest U.S. municipalities, has a peak rate of $0.2941/kWh and an off-peak rate of $0.1209/kWh.

We have an energy arbitrage of ：

peak rate — off-peak rate/energy efficiency

=$0.2941/kWh — $0.1209/kWh ÷ 90%

= $0.16/kWh

Since the cost of battery degradation ranges from $ 0.36/kWh to $ 0.89/kWh, the number does not work in Sacramento’s favor.

Example 2

Hawaiian Electric Company (HECO) has a peak rate of $0.492 /kWh and an off-peak rate of $0.097/kWh. We have an energy arbitrage of:

We have an energy arbitrage of ：

peak rate — off-peak rate/energy efficiency

=$0.2941/kWh — $0.097/kWh ÷ 90%

= $0.38/kWh

Here, the number works only for the charging frequency of 5 times per week.

Additional Consideration

This cost estimation does not include the service fees a third-party company might charge for its V2G program. The progress of corresponding regulations and the development of incentives might also change the energy storage landscape, hence the business model. For example, California has made moves to treat V2G as part of its Self-Generation Incentive Program.

Which manufacturers support V2H and V2G?

Currently, only Nissan Leaf and Mitsubishi Outlander support the V2H and V2G technology. More automobile makers are incorporating this feature into their upcoming products, including Kia EV6, Volkswagen, and Renault Zoe. However, Nissan is the only manufacturer currently guaranteeing a warranty period including V2H operations.

Montreal-based Dcbel has released its new all-in-one V2H capable charging unit. The unit utilizes solar energy for EV fast charging (Level 3 or DC Fast Charging). It is compatible with home solar systems with V2H features to match existing plug-in hybrid vehicles on the market mentioned above.

The bottom line

So far, a dedicated household energy storage system, such as Tecloman’s Firefly LFP battery, is still required for local storage. The cost of EV degradation can be as high as $ 0. 89/kWh. If the cost-benefit analysis of selling electricity to the grid works in your favour, you may consider taking advantage of the energy arbitrage rate in your region.

With the technology and regulatory developments of V2H technology, the future of powering your home with an electric vehicle is on the horizon.

About Tecloman
Tecloman offers high-quality energy storage solutions featuring advanced technology for reliability, efficiency, and sustainability. You can find us on LinkedIn, or reach out to us at: marketing@tecloman.com.
About the Author
Yushuo (Alicia) Cai has been working in the renewable energy and carbon accounting field for four years. She is currently the market research analyst at Tecloman. You can connect with her on LinkedIn.