Overview

The IAMMETER WPC3700 is not a standard energy meter. It is a single-phase Wi-Fi power controller built to linearly adjust the power of resistive loads such as electric water-heater elements and similar heating loads.

Its strongest use case is simple: when a home has rooftop solar and often exports energy in the middle of the day, the WPC3700 can push more of that surplus into a controllable heater load instead of letting it leave the home.

For a deeper buyer-oriented walkthrough, read the companion article: IAMMETER WPC3700: What It Does, How It Works, and When It Makes Sense.

What It Does Best

  • Linear power control for resistive loads instead of simple on/off switching
  • Standalone manual control through the app or local API
  • Auto mode with IAMMETER meters so output follows measured grid import/export conditions
  • Solar-surplus hot-water control for homes trying to improve self-consumption
  • Open local integration options through HTTP API and MQTT-oriented firmware settings

Two Main Working Modes

1. Standalone control

In manual mode, the WPC3700 can be used as a Wi-Fi-connected power controller on its own. You set the maximum load power and the target output power, and the controller adjusts the load accordingly.

This is the better fit when you already have your own automation logic in Home Assistant, Node-RED, or a custom local system.

2. Auto mode with an IAMMETER meter

This is the more interesting mode for solar homes. When paired with a compatible IAMMETER energy meter, the WPC3700 can react to measured grid power and automatically change heater power in real time.

That means it can:

  • keep grid import under a chosen threshold
  • follow solar surplus more smoothly than a simple timer or relay
  • increase self-consumption without needing a battery for this specific load

Key Specs That Matter in Practice

  • Single phase design
  • 220V-260V, 50-60Hz supply range
  • 3700W maximum output class
  • 0-98% output voltage control using phase-shift control
  • Built-in 2.4 GHz Wi-Fi with local setup page
  • Overheating protection

API and Integration Notes

The WPC3700 is more flexible than many diverter-style products because IAMMETER documents local APIs for:

  • setting output power with /api/setpower
  • reading and writing advanced parameters with /api/getadv and /api/setadv
  • configuring Wi-Fi parameters with /api/setwifiadv

It also exposes settings related to MQTT and Home Assistant discovery in the advanced parameter set, which makes it more attractive for people who want to integrate it into a broader automation stack.

Who It Fits

The WPC3700 makes the most sense for:

  • solar homes with an electric storage water heater
  • users already running IAMMETER meters
  • technically confident users who want local API control
  • households trying to improve solar self-consumption without jumping straight to battery storage

What To Watch Out For

This is not a general-purpose smart load controller for every appliance.

Important limits:

  • it is meant for resistive loads, not every motor or electronics-heavy appliance
  • it is single-phase only
  • it works best when the load is a strong match for solar-surplus control, especially hot water or simple electric heating
  • some households may still prefer a timer, contactor-based schedule, or battery depending on tariff structure and use pattern

Bottom Line

The WPC3700 is a practical niche device: not for every home, but very useful in the right one. If the goal is to convert midday solar export into controllable heater demand with finer control than a simple on/off relay, this is one of the more automation-friendly options in IAMMETER's lineup.