A home battery can be expensive for several reasons:

1. Battery technology: The cost 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 the cost of batteries has decreased over the years, they remain relatively high compared to other energy storage technologies.

2. Economy of scale: Home batteries are not yet produced on a large scale compared to other electronic devices like smartphones. This often results in a lack of economies of scale that could 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. Professional installation is often required to ensure that 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 adjustments.

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

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