What Home Backup System is Best For My Home?

If you know, you know: when a power outage strikes, we all go through the same motions. Maybe we stumble in the dark for candles or flashlights, or triple-check our phone batteries to see how much juice we’ve got left. But one thing we all do is try to plan ahead in an unfamiliar situation, asking ourselves questions like “Is the milk going to go bad?” or “Does my laptop battery have enough to meet my work deadline?” and maybe “should I invest in a home backup system?”.

Thankfully, there are a few ways to provide your home with power during an outage so that you don’t have to ask these questions. Each system has its own set of benefits and constraints. In this post, we'll explore different types of home backup systems, from generators to electric vehicles, to help you think through your decision.

What is Home Backup?

“Home Backup” is an alternative means to provide electricity to your home when the main electricity supply - from the electric grid - is interrupted. Power can go out for any number of reasons, from local issues like a blown transformer on a nearby power pole to regional issues such as when high winds and fire risk force your electric utility to de-energize portions of the grid for safety reasons. No matter the cause of the outage, Home Backup turns your home into an “island” of electric power,  capable of powering essential appliances and systems in your home until the grid comes online.

How You Should Think About Home Backup

As with any kind of preparedness exercise, you should consider both the challenge and its dimensions, as well as the solutions to that challenge, or what you need to be sufficiently comfortable. When you leave the house for a walk, does your everyday carry include just your wallet, keys and phone, or does it also include snacks, a leatherman tool and a water bottle? Does your earthquake emergency kit have a few granola bars and water bottles or a filtration system and a store of heritage grains? 

Thinking about Home Backup means a few key considerations:

• How long and how often are your outages? You may live in an area with frequent 2-3 hour outages, like those in high fire risk areas, or you might be preparing for the big one that comes one or two times a year from the seasonal ice storm or hurricane but tends to knock out power for days. The longer the outage lasts, the more energy you will need over time.

• Do you want backup power for a few things or all the things? This is often referred to as a choice between ‘Whole Home’ and ‘Partial Home’ Home Backup. In Partial Home Backup, your Home Backup system is wired to a few, critical circuits in your home that you pre-select, usually attached to appliances that you need to work during an outage (your refrigerator, for example). It is less expensive overall than Whole Home Backup, because the installation is less complex, the technology has a lower price, and because you are only powering important systems during an outage, you need less energy. In Whole Home Backup, your entire home is capable of running on your backup system, which means minimum inconvenience, but at greater cost to install and to manage during an outage. You might be surprised how fast your non-essential appliances use up your energy. Energy Intensity - or how much energy your home consumes each hour of an outage - is one crucial factor in evaluating a home backup system. Or put another way, a home backup system with a limited energy capacity like a battery will last longer if energy use is more conservative.

• How much / what kind of backup power do you want? One answer to this question the combination of the two previous concepts: expected Outage Duration/Frequency multiplied by your Energy Intensity. The longer the outage, and the more systems you intend to power during an outage, the more energy you need, and the bigger or more comprehensive the Home Backup solution might have to be, and vise versa. 

‍Types of Backup Systems

There are three primary types of home backup systems - Backup Generators (or BUGs), Stationary Energy Storage (Batteries), or Electric Vehicles (EVs). We’ll cover each of them, and their own unique set of strengths and weaknesses, in this section. We’ve ignored comparing things like maintenance costs or fire risk for simplicity – each of these are machines that contain combustible fuel and can mechanically break.

Backup Generators (BUGs)

‍BUGs are gas-powered generators that range in size and power output. They are no different technologically than an internal combustion engine in a car, but instead of turning a gearshaft, an electric current is generated. The technology is old enough to be very efficient, even though it still burns fuel and generates carbon emissions. Small enough to be portable and power key systems, some are big enough to power entire homes.

• BUG Upsides: Because the technology is older, mass produced, and purpose-built to provide backup power, a BUG is generally less expensive than alternatives. Portable versions can be moved around without any installation costs, which can be useful if you want to be flexible with your backup options. And because it runs on fuel, it can be re-fueled and operate over long durations, provided it’s well maintained and you have access to a gas supply.
• BUG Downsides: As with any combustion technology, BUGs can be noisy during operation. Additionally, they do require refueling which can add additional operational costs and inconvenience, especially if gas supply is unavailable. Lastly, BUGs need time to ‘spin up’ to operational levels - this can result in downtime between outage and backup power as little as ~10 seconds.

Stationary Storage (Batteries)

Batteries, not much different technologically from the disposable battery that powers a flashlight, are now available in a size that can power your whole home at a price that is growing more affordable. They can complement electrification technology like solar and EVs, or provide backup power using energy charged from the grid.

• Battery Upsides: Batteries are much quieter than BUGs and can provide seamless backup power with no spin up time. They can also be used to manage and lower utility bills by charging by switching your home to battery power when energy is expensive, or even selling stored energy back to your utility at a premium, which can lower the cost of the system over time. The ability to charge from on-site solar reduces the carbon footprint of your backup power, as well as mitigates the battery’s limited capacity concerns - in an outage, solar can power the home during daylight hours and recharge the battery to extend backup power well into the evening. 
• Battery Downsides: Batteries are the more expensive option, even with their utility bill savings capabilities, in part because they require complex installation, even in a partial home backup situation. Batteries also have limited energy capacity; they can only discharge what they have stored in a power outage, which means energy has to be managed throughout an outage, even if the sun can recharge it the next day. 

Electric Vehicles (EVs)

‍Modern EVs, in addition to being your vehicle, have the potential to serve as a backup power source for your home with V2H – or vehicle to home – technology. The same technology that allows you to pull energy from the grid, through your home, and into your car with a charger instead reverses the flow of energy, letting you power your home while your car is parked there. 

• EV Upsides: EVs are cars first and foremost, which is important to remember because home backup capabilities are in addition to your standard EV car features. That said, EVs are also just like batteries but with wheels, which means they are rechargeable, can provide seamless backup and can be paired with clean renewable energy to lower carbon emissions. They are also significantly larger – sometimes as much as 10 times larger – than standalone batteries, which means that EVs can power Whole Home backup for longer. Using V2G (Vehicle-to-Grid) technology, EVs can also sell energy back to your utility at a premium price, which can help pay for the car, or at least lower your energy bills.*
• EV Downsides: EVs are the most expensive option on this list, in no small part because you are buying a multipurpose system whose primary use is transport, but also because Home Backup requires installing a V2H-enabled charger. Additionally, the EV battery, while large, still has a limited capacity, which is compounded by range tradeoff; any energy you use for Home Backup reduces the distance your car can travel before recharging, and vice versa. Finally, there’s always a chance that your EV is not at home during an outage, unlike purpose-built stationary storage or generators.

So Which Solution is Right for Me?

Choosing the right home backup system depends on your specific needs, your budget, and priorities. Generators are cost-effective; batteries provide a silent and clean solution but come with a higher price tag and limited capacity. Electric vehicles offer a versatile and potentially powerful backup option, but require additional equipment and careful management of battery usage. Consider your individual circumstances to determine the best solution for your home.

And also, remember that your individual circumstances might change your Home Backup needs over time. For example, maybe you are okay with different solutions for different types of outages, like whole home backup for short outages but willing to scale back energy consumption for long haul blackouts. Or maybe you are only able to make one major investment in technology and you are willing to accept some shortcomings to your backup needs in order to get some of the solution.

Friendly Disclaimer: at Bidirectional Energy, we see a bright future for Electric Vehicles to provide many services, including but not limited to home backup. You can read more about our mission here, learn more about the interaction between energy and money here, or understand the opportunity to turn your car into a money making machine with V2G, here. 

*An important note about lowering energy bills with an EV: by getting an electric vehicle and charging it at home, your energy bills will increase relative to before you brought home the EV. The extra electricity cost of recharging your car should net out with no longer having to buy gasoline (and could be further reduced with cheaper alternatives like rooftop solar), but it might still come as a surprise when you pay your utility bill the first time. When we highlight that an EV can be used with V2G and V2H to lower your electric bills, we are referring to your ‘I-now-own-an-EV’ electric bills, which even when lowered may still be higher than the before-times.

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