Can You Charge an Electric Car Off-Grid? Methods Discussed

Charging an electric car requires a reliable and sufficient power source, which currently is the grid. But how can you charge an electric car if there is a blackout and the power outage lasts a while? 

You can charge an electric car off-grid if you have access to a large generator or backup battery. You may also use a standalone solar panel installation, either private or commercial, but it should generate and store sufficient energy to charge your electric car battery. 

The science and technology behind charging your electric car using a generator, battery, or solar energy are not complicated; however, realistically using these methods can be challenging. Read on to learn more about how you can charge an electric car off-grid.

Can-You-Charge-An-Electric-Car-Off-Grid---Solar-Panels
The off-grid power source wattages cited on the table are running watts. Also, these charging times will vary per voltage and amperage differences.

What Methods Can You Use to Charge an Electric Car Off-Grid?

You can charge an electric car off-grid at a public or private station with sufficient onsite power storage, as Tesla has. Otherwise, you need a large generator, enormous backup battery, or solar panels with around 10 kW of power capacity to charge an electric car off-grid.

Suppose you are at Tesla’s V3 Supercharger station in Las Vegas, NV. This installation has 24 Superchargers operating at all times and has solar panels generating energy, independent of the grid. There is also an onsite power cabinet to store energy at this facility.

Can-I-Charge-My-Electric-Car-With-A-Generator

If you’d like to find out if You Can Charge your Electric Car With a Generator, check out this related and helpful article that I wrote. Here I also discuss the ins and outs.

Thus, you can easily charge a Tesla off-grid at this station. Also, the cap of up to 250 kW per Tesla is more than sufficient to charge the brand’s models in minutes, not hours.

Here’s a glimpse of Tesla’s V3 Supercharging in Vegas:

However, most Tesla and other electric car owners do not have off-grid facilities nearby. Additionally, solar panel installations throughout the country are not necessarily isolated or standalone systems. Many solar systems are integrated with the grid.

So, what other option do you have?

Charge an Electric Car Using a Generator

One viable option for charging your electric car is using a generator. Fortunately, you can use appropriate adapters to connect almost any electric car to a large generator. However, the caveat is ‘large.’ Let me use an example to illustrate the challenges of charging an electric car off-grid.

Suppose you own a Tesla Model S or X with a 100 kWh battery pack and have a generator with 1,000 running watts. You would need more than 100 hours for a drained 100 kWh battery to gain a full charge. 

A-Ipower Sua15000E Generator, Red
Say you have something like the A-iPower SUA15000E Generator (available on Amazon.com). This 15,000 W generator has a running wattage of 12,000. Hence, you can expect a maximum of 12 kW of power to charge an electric car. Therefore, you need around 10 hours to charge a Tesla Model S or X. 

However, the A-iPower generator with its 8-gallon (30 liter) tank will only last up to 7 hours when you operate the generator with a real-time load of 6,000 W (6 kW). So, you must refill the tank twice or more to charge your Tesla. 

The situation can be much better if you have a substantial charge in your electric car or use a larger generator. The charging time depends on the generator’s voltage and the battery’s amp draw. Albeit, recharging smaller electric car batteries is more manageable.

Here’s how the power source affects the charging time of electric car battery packs:

Off-Grid Power40 kWH Battery50 kWH Battery75 kWH Battery100 kWH Battery
5 kW8 to 10 hours10 to 12 hours15 to 16 hours>20 hours
10 kW4 to 5 hours5 to 6 hours8 to 9 hours10 to 11 hours
20 kW2 to 3 hours~3 hours~4 hours~5 hours
50 kW~1 hour>1 hour<2 hours~2 hours
100 kW<30 mins>30 mins<1 hour~1 hour
200 kW~12 mins~15 mins~20 mins~30 mins
This table shows the varying charging times for electric car batteries based on the power of an off-grid source.

Charge an Electric Car Using Solar Energy

Modern solar panels have a power range of 250 to 425 watts. One such solar panel generates around 1.25 kWh to 2.12 kWh energy during 5 hours of peak sunlight. Thus, you need at least 20 x 425 W solar panels (8.5 kW) to charge a 40 kWh electric car battery per day. 

Anyway, on a similar note, I also wrote a somewhat related article that discusses a Portable Power Units for Electric Cars. Check it out to find out which ones are the best.

Of course, this solar system cannot power anything else in your house if you need to use it as the off-grid source to charge your electric car. Also, 40 kWh batteries are mostly found in smaller electric cars with shorter ranges. 

20 x 425 watts solar panels producing 42.5 kWh per day will still be insufficient to fully charge a Tesla. Additionally, it can be challenging to find an area that has 5 hours of peak sunlight. So, the net energy generation and available power may be much less.

As an added bonus to this article, I’ve created this easy-to-use charging calculator. Simply input your model, charging wattage, and charging percentage, and you will get the estimated time it will take to charge a Tesla in terms of hours. You can play around with numbers a bit just to see how charging time changes:

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Tesla Charging Calculator (Time):

Estimated Time It Takes To Charge Your Tesla

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Erwin Meyer
Erwin Meyer

Thanks for visiting evspeedy.com. The goal of this site is to be a helpful resource for Tesla and EV owners as this is where my passion lies. I was a TSLA shareholder before the hype and still am. I also believe in Tesla’s speedy mission to accelerate the world to a sustainable future.