Energy Management


Streamlining local grid demand from domestic electric water heaters

Published: 25 March 2020 - Carly Wills

Nordic Semiconductor has announced that US engineering and product design agency, Apricity, is helping multiple power utilities in pilot field studies throughout the US to avoid having to rely on firing up environmentally-polluting auxiliary power stations to meet prime time demand. This is done using the 'Apricity Ara' cellular IoT and proprietary wireless mesh domestic water heater controller. 

The Apricity Ara employs both a Nordic nRF9160 multi-mode LTE-M/NB-IoT System-in-Package (SiP) and Nordic nRF52840 System-on-Chip (SoC), with the entire application running on the nRF9160's 64 MHz Arm Cortex-M33 application processor with 1MB of Flash and 256KB of RAM memory.

In operation, an Apricity Ara is attached in-line with the power supply of each water heater. This allows the heater to be controlled remotely by the local power utility using the LTE-M version of cellular IoT wireless technology. However, as some water heaters were located in environments with poor LTE-M coverage such as basements, Apricity found it also had to support the cellular communications with a proprietary wireless mesh. This enabled any Ara unit with no cellular service to communicate with any other Ara that had good cellular reception and continue to be controlled by the utility.

"In the US, tanked water heaters are often installed as always-on devices with no user- or demand-based control and so they continually consume energy reheating the water," explained Apricity COO, Jacob C Betcher. "During times of peak electricity demand, asking dormant hot water heaters to temporarily reduce their energy consumption is a very effective power load reducing method. With some simple local monitoring, it is possible to allow water heaters in-use to continue heating, while reducing standby heating of water heaters not in use."

Betcher continues: "Hot water tanks are, in effect, an energy storage medium and by making a large number smart you are effectively creating a huge energy storage tank. You can 'charge' this in a much more optimal way if allowed to have some control over which times of day the tank is actively heating stored water."

Apricity claims that it knows of no other company in the world developing such a dual cellular-proprietary mesh solution, or any other solution that will reach the price point it thinks the Apricity Ara can achieve in volume (hundreds of thousands of units).

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