In need of a device to charge my EV during hurricane power outage

[Fuhnominon]

Hello everyone,
I'm new to this forum and new to the EV community in general... only having just placed an order for my first EV. I live in the Caribbean and we are experiencing more hurricane activity these days and hence, more power outages for longer periods. I like to be proactive and as self-sufficient as I can be so I'd love to have a device to use as a back up stand alone charging device to charge my EV when there is a power outage, and ideally also be able to power some lights and appliances in the house if possible. Even if this means purchasing multiple devices. Does anyone have knowledge of devices I can buy to do these tasks safely?

 

[R P]

Solar panels and battery storage.

 

[bwilson4web]

I use this solar calculator: https://pvwatts.nrel.gov/ It provides the estimated power my contracted, solar roof:

• 28° roof pitch
• 16 four hundred watt panels
• adjusted for roof directions, latitude and weather
• 8,096 kWh/yr

If your solar panels are mounted on a sun following structure, you can get the maximum power. Then have a hurricane proof, storage for the panels.

I have two EVs so one is on charge while I drive the other. My EVs typically get 4 mi/kWh so I should see about 32,384 miles of EV range over a year.

Bob Wilson

 

[Fuhnominon]

I use this solar calculator: https://pvwatts.nrel.gov/ It provides the estimated power my contracted, solar roof:

• 28° roof pitch
• 16 four hundred watt panels
• adjusted for roof directions, latitude and weather
• 8,096 kWh/yr

View attachment 23753


If your solar panels are mounted on a sun following structure, you can get the maximum power. Then have a hurricane proof, storage for the panels.

My EVs typically get 4 mi/kWh so I should see about 32,384 miles of EV range over a year. I have two EVs so one is on charge while I drive the other.

Bob Wilson

Thanks so much for this info. I will look into it. Sounds like a major investment! Also looking for something simpler like a portable storage unit for now or generator or something

 

[bwilson4web]

Thanks so much for this info. I will look into it. Sounds like a major investment! Also looking for something simpler like a portable storage unit for now or generator or something

Mine is because the single most expensive part is a $20,000 smart electrical panel. When the grid goes down, it sheds the major loads so the solar panels and battery are not overloaded. In effect, I have instant acting, uninterruptible power. I also have a 16 kW, automatic, natural gas generator with a 30 second startup time for longer intervals.

My first emergency power was a modified sine wave, 1.1 kW, 12 V inverter mounted on a Toyota Yaris. I soon learned the engine had to be revved up to generate enough 12 power.

When I got a 2003 Prius, my first modification was to permanently mount the inverter. Testing showed a maximum of 1.1 kW was available because the Prius 12 V system provides 75 A @12.5 V or ~925 W. The small 12 V battery provided enough surge to handle a couple of minutes of 1.1 kW power. The 12 V power comes from the traction battery while the engine cycles ON/OFF as needed for traction battery voltage.

When we had power outages, I would backup the Prius to the kitchen door and leave it in park. Then I ran a 3-socket, contractor cord into the kitchen and fanned out three extension cords for critical loads:

• heater fan or window air conditioner
• lights and communications

In April 2011, tornadoes tore up the power transmission lines and we had a 4 day, 6 hour power outage. The Prius powered our house for ~2 gallons per day.

In 2016, I had the house power upgraded to 200 A and added an automatic, natural gas fueled, 16 kWh emergency generator. This because I didn't want my wife left in the dark in a power outage. But the natural gas costs about $0.45/kWh versus the grid $0.12/kWh.

In November 2024, I had a bunch of Tesla stock and realized the CEO had become distracted. Worse, it pays no dividends as the only profit occurs when you sell it. So I decided to move the Tesla stock capital into a solar roof that will pay me an annual dividend in monthly electric savings.

Bob Wilson

 

[Keith Smith]

Random . . . EG4 12000XP AIO (240/120v split phase 50A, up to ~18KW of PV) is $2500, EcoWorthy stack of 6 100A 5KWH $5000 (30KWH total), 400W Solar panels were just on sale at SanTan ~$100/ea, get a pallet of 31 $3100 (12000W on paper, figure 6KWH for each hour of good sun). Add some wire, etc, you are talking < $13K all in, shipping to the Caribbean is going to hurt a bit. You can cut back on the panels, but a pallet is generally less expensive, than 24 individually.

You can do a generator, it's just going to be ridiculously expensive to charge a car with it. I'd go with solar, or just make sure your car is always 100% charged every morning. You can't possibly be driving far enough for it to be relevant if the grid power was out for 2-3 days, you should get 250 miles or much more with most EV's, driving around on surface streets under 60MPH. Solar will pay you back over the long haul

What is your normal electric usage each month and your rates. That will tell you if solar is worth the effort. You will want a good L2 EVSE.

 

[Bruce M.]

I live in an area (Hawaii) where hurricanes are rare but possible -- we had a near-miss in August that caused some flooding and the intense rain caused some minor damage to my house, but nothing serious -- and I would never consider spending thousands of dollars on any sort of charging system for the eventuality of a worse one. Hurricanes always come with at least a day's advance warning, usually more. If that happens, I'll just charge my car to 100%. If it's bad enough that I'm without power for more than a couple days, I ain't staying in the house (which probably won't be intact) anyway.

 

[aamyotte]

Another option is to just have battery backup like Powerwall or EG4 or others then add PV later on as budget allows. As suggested by Bruce, charge to 100% just before the storm hits then you won't need to rely on the battery as much extending the capacity.

 

[qmail9]

A solar generator, which combines a battery with solar panels for recharging, could be a more sustainable option for longer outages, but its charging capability will depend on sunlight availability. For more substantial backup to power your EV and home, you might consider a home battery system like a Tesla Powerwall or similar, especially if paired with solar panels. These can store significant energy and some EVs even have vehicle-to-load (V2L) capabilities, allowing them to power your home directly. It's crucial to check the power output and capacity of any device to ensure it meets your needs safely.

 

[bwilson4web]

I would share these observations from my 2019 Model 3:

• 4 mi/kWh - defines the driving miles as a function of added charge
• 6 A - lowest charge rate amps
• 120 / 240 VAC - typical voltage range from split phase, N. America home
  • 120 / 208 VAC - commercial 3 phase voltages

Today, my 6 year old, 150,000 mi, Model 3 has ~45 kWh battery capacity.

There is a triangular shaped charging curve. Measured at home, the initial rate was 7.4 kW and then tapered down to ~1.2 kW.

My home solar roof is not fully operational. But during testing, it generated 4 kW at 4 PM in the afternoon (for my configuration, sixteen, 400 W panels.) My best estimate from an EPA solar planning web page is the daily production should annually average, ~25 kWh per day.
Given these recent metrics:

• 2/3d (16.5 kWh) - EV charging, ~66 mi per day
• 1/3d (8.5 kWh) - house usage per day

I would recommend adding a high efficiency, electric bicycle for local, emergency transportation and leave the EV for longer range, larger payloads, and passengers.

Bob Wilson