A complete grid-to-appliance dynamic pricing system — running on $5 hardware, 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.
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 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.
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.
We’ve shown this complete grid-to-appliance Price-based Demand Flexibility with OpenADR 3 system at: