Price-based Demand Flexibility with OpenADR 3

A complete grid-to-appliance dynamic pricing system — running on low-cost single-board computers, built entirely from open standards and open-source software.

Hourly OpenADR 3 prices stream from the cloud to a customer gateway, then flow over the local network to appliances — an EV charger, water heater, and HVAC system — that each autonomously optimize against the current price. No proprietary clouds. No per-device control. No aggregators. Just dynamic prices, open protocols, and software running on inexpensive microcontrollers.

This is not a simulation. It’s a working system, built by four volunteers in one month, that you can build yourself.

The demonstration board: a house outline with an OpenADR 3 price server in the cloud, a Home Assistant gateway inside the home, and tablets showing an EV charger, water heater and HVAC unit each responding to the current hourly price

The board as demonstrated at the 2026 CEC/EPRI Electrification Summit. Every screen is live: the gateway is fetching real California prices, and each appliance is deciding what to do with them on its own.

What We Built

A grid price server communicates hourly dynamic prices via OpenADR 3 to a customer gateway, which then distributes those prices over the local network to mock appliances — an EV charger, water heater, and HVAC system. Each appliance independently optimizes its behavior based on the current and forecast price.

The Architecture

Grid price server in the cloud sends OpenADR 3 over the Internet to a Home Assistant gateway in the home, which republishes prices on the local network to an EV charger, water heater and HVAC unit

How Appliances Use Prices

Each load optimizes against the current price and forecast. The demo uses a simple algorithm for illustration — real products would be more sophisticated, optimizing across many hours using thermal storage (water heater), electrical storage (battery), or deferred service delivery (pool pump, EV charging).

When the price is low, deferrable loads run. When the price spikes, they curtail. The gateway computes an effective local price that accounts for self-generation and storage, so appliances always see the most relevant signal.

Hardware

Component Hardware Cost
Gateway Raspberry Pi 4 ~$35
Load controllers Raspberry Pi 4 (demo); ESP32 would suffice in production ~$35 as demonstrated; ~$5 in quantity for an ESP32

The ESP32 — a microcontroller with integrated Wi-Fi costing under $5 — is representative of what’s already inside most network-connected appliances today. Manufacturers have no technical or cost barrier to incorporating OpenADR 3.

Software

The gateway runs Home Assistant — free, open-source home automation software used in approximately 2 million homes worldwide — augmented with our OpenADR 3 client libraries.

The Prices

The demo uses live California electricity prices streamed from our own public Grid Coordination price server — the same OpenADR 3.1.0 service anyone can connect to today. For presentation, time is compressed so each hour plays out in 5 seconds, making a full “day” visible in about two minutes. OpenADR 3 handles arbitrary price intervals — most dynamic pricing programs worldwide use hourly granularity today.

Why This Matters

This demo was built by four volunteers in their spare time over one month, using freely available open-source software. If four people can build a complete grid-to-appliance dynamic pricing system in a month, manufacturers will have no difficulty incorporating OpenADR 3 into their products.

The system illustrates that flexible demand appliance standards mandating network connectivity and open protocols are easily implemented at low or no incremental cost. The technology is ready. The regulatory framework is catching up. The only thing missing is the mandate.

Key Takeaways

Where We’ve Demonstrated

We’ve shown this complete grid-to-appliance Price-based Demand Flexibility with OpenADR 3 system at:

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