Home batteries aren’t just for doomsday preppers. Here’s why you might want one

With electricity costs Booming, home batteries have never been more attractive. Whether you want to store the excess generated by your solar panels or simply buy electricity at the lowest possible rate to use later when energy is most expensive, a home battery can help. It’s never been easier to install a home battery, but this rapidly expanding market can be confusing, and there are several things to consider before purchasing.

I spent months researching home batteries, talking to people who use them, and then I installed one myselfand I have advice for anyone looking to get their own home battery.

Why would you want a home battery?

There are several reasons why you might want to invest in a home battery, and they are not mutually exclusive:

• You want to store excess energy from your solar panels.
• You want to live off-grid.
• You want to protect yourself against power outages.
• You want to buy electricity cheaply and store it for later use.

Home batteries are a win-win solution, which can also benefit power companies, as battery storage is an essential part of network balancing and can help manage and make the most of intermittent energy generated by renewables (solar, wind, waves).

How do household batteries work?

A household battery is like a big power bank for your home. But rather than lithium ion, they tend to be lithium iron phosphate (LFP or LiFePO).₄), because it is safer, more durable and less prone to thermal runaway. In other words, less likely to overheat and catch fire. A few manufacturers are working with sodium-ion (Na-ion) batteries, which are potentially cheaper, more environmentally friendly (they don’t require lithium), and work better in cold weather, but they are also larger and don’t last as long.

Home battery technology is often the same as that found in electric vehicles. Some people have even suggested use EV batteries as home batteries. But this presents potential problems, including finding that your car battery is dead in the morning. Electric vehicles also advance technology towards solid state batterieswhich are smaller for the same capacity, safer because they do not contain liquid electrolytes inside and which last longer.

Many home batteries come in modular systems, so you can add the capacity you want, but they require an inverter to convert the stored DC (direct current) energy into AC (alternating current) energy you can use. People with solar panels, or those who plan to add more in the future, should opt for a hybrid inverter, which can also convert the panels’ energy for use or storage.

Inverters have different kilowatt (kW) ratings that dictate how much power you can consume at any given time. Households with modest needs can get by with a 3.6 kW inverter, but this limits your continuous consumption to 3.6 kW. They usually have a peak load capacity that increases, allowing you to pull more for a brief period of time. If you have high-demand devices like an EV charger or heat pump, you’ll need at least 5 kW, and people with higher demands or larger batteries will want to go higher (6-10 kW).

What should I look for?

There are several things to look out for when purchasing a home battery:

• Ability: Measured in kilowatt hours (kWh), this tells you how much total energy the battery can hold.
• Output power: Measured in kilowatts (kW), this indicates how much power the battery and inverter can provide at any time.
• Depth of discharge: This is the capacity of the battery that you can safely use without damaging it.
• Efficiency: This is the percentage of the energy you put into the battery that you can actually use, because some energy is always lost during the storage process.
• Guarantee: This is a guarantee on the minimum performance you can expect before a battery degrades (they all degrade over time), and is often stated in years and charge cycles (whichever comes first). For example, EcoFlow promises at least 70% capacity after 15 years or 6,000 charge cycles.

How much home battery do you need?

It can be difficult to calculate how much battery capacity you need, and it depends on your use case. If you want to protect against outages or live off-grid, you need to consider the amount of energy you use over time as well as the sum of your maximum electricity consumption at any given time to ensure your kWh capacity and kW output are sufficient. If the wattage isn’t high enough, you may not be able to run power-hungry appliances at the same time, so you’ll need to think about how you use your energy.

For people like me, who are just looking to buy at a cheaper rate to use when electricity is more expensive, any capacity will benefit you. But if you’re getting a cheap six-hour overnight rate, for example, you ideally want it to last the remaining 18 hours. It makes sense to get as much as possible up front because installation costs are high. Even adding modular systems later often requires professional installation to avoid voiding your warranty.

Do you need upgrades or authorization?

The home battery will connect to your main electrical panel via cable and may require some upgrades. There was no room on my fuse board when I installed a house battery, so they had to install a second breaker box.

Some inverters may require authorization from your local electric utility or distribution company. Here in Scotland, the distribution network operator must approve your inverter, but you can install and then notify up to 3.6 kW, while larger inverters require prior approval.

Obtaining permits can take time and may have associated costs in some locations. So it’s a good idea to find out early. Most reputable installers will offer advice and guidance and can even complete the process for you.

Home Battery Installation Tips

Here are some additional tips on what to consider before your installation.

• Look for installers with the right certification (MCS in the UK), read reviews and get at least three quotes to compare.
• Find a good place for your battery and check the dimensions.
• Remember that installers will need to run the cable from the electrical panel to the battery; this could be disruptive and require drilling and re-assembling the floors. My installation required a site visit beforehand for planning and was then completed in one day.
• Although many home batteries are weatherproof, they are often best stored in your garage or basement. It’s not just for aesthetic reasons. Batteries don’t work as efficiently in cold weather. Some home batteries come with a built-in heater for this reason, but this uses energy.

Many home batteries come with a tablet-style screen, sometimes as an option. It’s easier and potentially cheaper to just use an app on your phone.

How much does it cost?

Much of the cost is related to the professional installation of these systems. If this puts you off (or if you’re renting out your home), there are alternatives to consider, like the plugin solar panels for balcony And portable power stations. But these DIY systems can only generate, store and use a limited amount of energy, and current rules vary by state and country. A fixed domestic battery is probably more efficient.

Several factors come into play to determine how much your system will cost and what your return on investment (ROI) could be. My EcoFlow PowerOcean System with a 6kW hybrid inverter and a 10kWh battery it would cost you £6,500 (additional 5kWh batteries cost between £1,000 and £1,500). A typical 10 to 15 kWh system fully installed in the United States will likely cost between $8,000 and $15,000, depending on the electrical work.

It is worth checking if there is all incentives still available. There could be local tax credits, government grants or loans, or regional utility rebates. Installers will usually be able to advise you of any systems that can reduce costs. You can also get a better deal by combining your home battery installation with solar panels or a heat pump.

The return on investment will depend on your local electricity rates and how you use your home battery. I expect mine to pay for itself in about six years, based on my current rates and savings, but it may take you five to 12 years to realize your costs. People combining home batteries with solar panels and off-peak tariffs will see the biggest benefits.