Home Batteries: How They Are Installed and Their Cost

It is electronic money up, home batteries never looked so pretty. Whether you want to store excess energy produced by your solar panels or simply buy electricity at a very low cost to use later when the power is too high, a home battery can help. It’s never been easier to install a home battery, but the fast-growing market can be confusing, and there are a few things you should consider before buying.

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

Why Do You Need a Home Battery?

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

• You want to keep more energy from your own solar panels.
• You want to live off the grid.
• You want to avoid power outages.
• You want to buy electricity at a cheap price and save it for later use.

Home batteries are great, which can also benefit the energy industry, because battery storage is very important grid balancing and it can help manage and efficiently use intermediate energy produced by renewable sources (solar, wind, waves).

How Do Home Batteries Work?

Photo: Simon Hill

The house battery is like a big one power bank to your house. But instead of lithium-ion, they tend to be lithium iron phosphate (LFP or LiFePO₄), because they are safe, durable, and don’t tend to run away due to heat. In other words, very little is burned and burst into flames. There are a few manufacturers that work with sodium-ion (Na-ion) batteries, which are cheap, environmentally friendly (doesn’t require lithium), and do well in the cold, but they are bulky and don’t last long.

Home battery technology is often similar to that found in electric vehicles. Other people have also suggested using EV batteries as home batteries. But there are potential problems with this, not least finding your car battery dead in the morning. EVs are also driving technology forward solid batterieswhich are small for the same power, safe because they do not have water electrolytes inside, and long.

Most home batteries come in adjustable systems, so you can add as much power as you need, but it requires an inverter to convert the DC (direct current) stored power to AC (alternating current) power that you can use. People who have solar panels, or who plan to add them in the future, should choose a hybrid inverter, which can also convert the energy from the panels for use or storage.

Inverters have different capacities in kilowatts (kW) that indicate how much power you can draw at any given time. Households with lower needs can have a 3.6-kW inverter, but this will limit your maximum output to 3.6 kW. They usually have a very high interest rate, which allows you to draw a lot in a short period of time. If you have high-demand equipment like an EV charger or heat pump, you’ll need at least 5 kW, and people with larger or larger batteries will want to go higher (6 to 10 kW).

What Should I Look For?

There are a few things to keep in mind when buying a home battery:

• Power: Measured in kilowatt-hours (kWh), this tells you how much power the battery can handle.
• Energy release: Measured in kilowatts (kW), this shows the power that the battery and inverter can provide at any given time.
• Depth of discharge: This is the amount of battery power you can safely use without draining it.
• Good performance: This is the amount of energy you put in the battery that you can use, because some energy is always lost in storage.
• Confirmation: This is a guarantee about the minimum service you can expect before the battery wears out (everything wears out over time), and is usually expressed in years and mileage (whichever comes first). For example, EcoFlow promises at least 70 percent energy efficiency after 15 years or 6,000 charging cycles.

What Kind of Home Battery Do You Need?

It can be difficult to calculate how much battery you need, and it depends on your usage. If you want to avoid blackouts or being off the grid, you need to consider the amount of energy you use over time and the amount of energy you use at any given time to ensure that the kWh and energy output in kW are correct. If the output isn’t high enough you can’t run the electronics at the same time, then you need to think about how you use your energy.

For people like me, just looking to buy at a cheap price to use energy when the price goes up, every energy will be worth it. But if you have a low price of six hours overnight, for example, then you want it to last another 18 hours. It makes sense to get as much as you can up front because the investment costs are high. Even later additions to modular systems often require professional installation to avoid voiding your warranty.

Do You Need Additional Information or Permission?

The home battery will be connected to your main electrical system via a cable, and may need to be upgraded. There was no room on my fuse board where I put the house battery, so they had to put in a second broken box.

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