A home battery can be expensive for several reasons:

1. Battery technology: The costs of the battery technology itself can be a significant factor. Batteries with high power and long lifespan can involve substantial research and development costs. Although battery costs have decreased over the years, they remain relatively high compared to other energy storage technologies.

2. Economies of scale: Home batteries are not yet produced on a large scale compared to other electronic devices like smartphones. As a result, they often lack the economies of scale that can lead to lower production costs. As the demand for home batteries increases and production is scaled up, costs may potentially decrease further.

3. Installation costs: In addition to the cost of the battery itself, there are also installation costs. A professional installation is often required to ensure the home battery is correctly installed and connected to a home's electrical system. These installation costs can vary depending on the complexity of the installation and any necessary modifications.

4. Warranties and safety standards: Home batteries must meet stringent safety standards, and manufacturers often offer extensive warranties to protect the consumer. These factors can increase the costs of a home battery.

It's important to note that the costs of home batteries have decreased over the years and are expected to continue decreasing as the technology evolves, production shifts, and the market grows.