How to Make Water Heater With Battery

July 16, 2023
David Sunnyside

Every time you turn on your coffee maker or microwave, they draw on some form of electricity to heat things up. But there’s a much more efficient way to do this with a little bit of solar power.

In fact, an electric water heater can be made to work just like a battery, storing energy as heat rather than cold. And that makes it a lot cheaper than buying something like a Tesla home battery, which stores just 7 kWh and costs more than $5,000.

One company in Hawaii is tackling this challenge with a unique approach. It’s converting ordinary electric water heaters into virtual power plants by equipping them with a small box that can communicate with the grid.

That box, called Shifted Energy’s Virtual Water Heater, connects to a water heater via a standard wire and a cellular connection. Its software predicts down to the kilowatt-hour just how much electricity a household needs for hot water at different times of day. Then it remotely programs the devices to absorb excess solar power when it’s being generated and then sell that back to the electricity grid.

The company has sold a few hundred of the boxes and says they could be installed in every home in America, including those in low-income housing where rooftop solar, backup batteries and electric vehicle chargers are more expensive. That’s a big promise, but it would also be an incredibly simple and affordable way to help people go zero-energy.

David Sunnyside
Co-founder of Urban Splatter • Digital Marketer • Engineer • Meditator
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