Web of Things-Driven On-Device Automation for Resource-Constrained Energy Devices

Abstract

Energy-related Internet of Things (IoT) devices such as inverters, storage systems, heat pumps, and Electric Vehicle (EV) chargers are increasingly connected and remotely controllable, yet their integration logic is often tightly coupled to specific standards, service providers, or vendor clouds. As protocols and business processes evolve, this coupling can lead to vendor lock-ins or complex gateway-based compatibility layers, which make local fallbacks or user-defined automation difficult. At the same time, most residential energy automations are conceptually simple and follow a consistent pattern: ingest a signal (e.g., dynamic tariffs or local PV surplus), evaluate it against a policy, and actuate a device accordingly. In this paper, we explore how these automations can be enabled on resource-constrained hardware using standardized, machine-readable interfaces. To this end, we present a software architecture that realizes a consumer-side subset of the Web of Things (WoT) Scripting API on embedded devices, including consume, readProperty, writeProperty, and invokeAction. The architecture supports asynchronous I/O via an on-device JavaScript executor and exposes additional device functionality to scripts through host bindings. To quantify the limits of our approach, we evaluate practical resource costs on an ESP32 using an energy automation scenario and report on firmware footprint and memory usage. Overall, the results indicate manageable firmware and memory overhead, demonstrating the feasibility of deploying standards-based automation logic directly on constrained IoT devices.