At the 2025 California Demand Flexibility Summit, hosted by the California Energy Commission, we demonstrated a complete grid-to-appliance coordination system using OpenADR 3, open-source software, and inexpensive hardware.
The demo showed what we’ve been advocating: dynamic pricing delivered over open protocols, driving autonomous local optimization of household loads. Not a simulation — a working system.
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.
Cloud Customer Home (LAN)
┌──────────────┐ ┌────────────────────────────────┐
│ Grid Price │ OpenADR 3 │ Gateway / HEMS │
│ Server (VTN) │────────────>│ (Home Assistant + OpenADR VEN) │
└──────────────┘ │ │ │
│ OpenADR 3 (local) │
│ ┌────┴─────┬───────┐ │
│ v v v │
│ EV Charger WH HVAC │
└────────────────────────────────┘
Each load optimizes against the current price and forecast. The demo used 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.
| Component | Hardware | Cost |
|---|---|---|
| Gateway | Raspberry Pi 4 | ~$35 |
| Load controllers | Raspberry Pi 4 (demo); ESP32 would suffice in production | ~$5 in quantity |
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.
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 demo used “SpringHDP” prices from CalFlexHub, derived from real CAISO wholesale prices with the vertical scale stretched for visibility. Time was compressed so each hour played out in 5 seconds, making a full “day” visible in two minutes. OpenADR 3 handles arbitrary price intervals — most dynamic pricing programs worldwide use hourly granularity today.
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.