Whole-Home Battery Backup

The PropertyClub Team
Oct 20th 2020
How do home battery backup systems work and can they really power your whole house? Here's everything you need to know before you purchase a battery backup for your property, including how much they cost.

Nobody likes dealing with power outages. They can be a slight nuisance at best or imminently dangerous at worst. If you live in an area with frequent power outages, then you have probably considered getting back up power for your home. 

There are several options you could consider at this point. One of those options is a whole-house backup battery. Whole-home backup battery systems are a relatively new development and serve as an alternative to traditional methods such as a whole-home generator. 

So we put together this comprehensive guide on whole-house battery backup systems and whether they are a viable and cost-effective option. 

Can You Run Your Entire Home on a Backup Battery?

The first most obvious question is whether you can actually run your entire home off a backup battery system. 

As is the case with any power systems, there are limits to how much energy a battery can provide. Unlike standard power grids, battery power is limited by overall battery capacity. Whether a backup battery can power your entire home depends on the battery size, your electrical needs, and the duration you need the battery to operate. 

The average American home uses approximately 909 kWh of electricity a month, which comes out to around 30 kWh per day. Right now, the most powerful whole-home battery system on the market is probably the Tesla Powerwall 2, which can supply 13.5 kWh or power off of a full charge. 

However, you are not limited to just one battery. Most backup battery systems have multiple battery stacks and can produce enough power to run your entire home’s electrical system for at least a few hours. The average American home needs about 2-3 Tesla Powerwall 2 batteries to power everything in their home for a day. 

Most of the time though, you will not be relying on battery power for an entire day, so a single battery can run critical systems like appliances and equipment. The greater your power needs, the more backup batteries you will need to buy. 

How Do Home Battery Systems Work?

Home battery backup systems perform the same function as a generator but work differently. Instead of producing energy like a generator does, backup batteries store energy for use when the electrical grid is down. During power outages, the battery will disconnect from the power grid and start supplying your home with energy. The result is you have a self-contained source of power for your house. 

Most current backup batteries are either lithium-ion batteries (like the ones in your laptop) or lead-acid batteries (like the one in your car). 

Lithium-ion batteries are more environmentally friendly and are better for reducing your carbon footprint. Traditionally, lead-acid batteries were considered more powerful and were the go-to choice for off-grid power supply, but advances in battery technology have made lithium-ion batteries superior in virtually every way. 

The batteries are installed in your home, normally behind your electrical meter inside. Modern lithium-ion batteries are water and dust-resistant and so can be installed outside. 

When the electrical grid is up and running, the battery charges. When the grid goes out, the battery then disconnects itself and starts powering your home. 

Backup Battery Benefits

Backup battery systems have several advantages over backup generator systems. Here are just a few of them. 

Fuel Costs

Generators typically use natural gas or propane. As long as you have fuel, the generator can continuously provide power. Natural gas generators can be connected to existing gas lines, so you do not have to refill them. 

Battery back up systems, in contrast, use electricity and charge themselves from the city’s power grid or a solar panel array. Due to this power source, battery backup systems usually cost less to charge and maintain. 

Additionally, solar-powered batteries virtually have no field costs because sunlight is free. Solar arrays and battery systems typically have a high upfront cost, though.

Environmentally friendly

Gas-powered generators rely on fossil fuels, which produce a lot of excess carbon. In contrast, battery backup systems run entirely on electrical power, which lowers your overall carbon footprint. Battery backup systems are not completely carbon-free, as the electricity used to charge them often comes from fossil fuel sources. 

Room for advancement

Battery technology has grown by leaps and bounds in recent years, and they still have a lot of potential. Generator advancements have generally stalled. Batteries have a lot of future potential as sources of power.

How Much Does a Backup Battery System Cost?

The major downside of backup battery systems is the relatively high upfront cost. The average cost of a backup battery system for a medium-sized home falls anywhere between $10,000-$20,000. Fuel generators, in contrast, cost around $5,000-$12,000. 

However, even though the upfront cost might be higher, batteries are potentially more cost-effective in the long run. Batteries require relatively little maintenance, while a fuel-powered generator may cost upwards of $300-$400 in maintenance and repairs every year. 

Batteries may also help you save on utility costs as you can alternate between your battery and electrical grid when utility prices rise and fall. When utility costs go up, switch to your battery more frequently. When utility costs go down, you can stick with your electrical grid. 

If you want a solar-powered battery system, you will also need to pay for a solar panel array. Installing a solar panel array can cost an extra $10,000-$15,000 on top of the cost of the battery itself. But solar-powered battery systems virtually eliminate fuel costs so they can pay for themselves rather quickly. 

Other costs associated with a backup battery system are installation costs. While you can install a battery backup system on your own, we do not recommend doing this unless you have extensive experience with electrical systems. The best option is to get the services of a professional. They can help you determine your energy needs and the most efficient way to install your whole-house battery backup system.