fix(growatt): skip battery telemetry when no battery is connected

drivers/lua/growatt.lua

@@ -21,7 +21,7 @@ DRIVER = {
   id           = "growatt",
   name         = "Growatt hybrid inverter",
   manufacturer = "Growatt",
-  version      = "2.1.2",
+  version      = "2.1.3",
   protocols    = { "modbus" },
   capabilities = { "meter", "pv", "battery" },
   read_only    = true,
@@ -181,14 +181,23 @@ function driver_poll()
         bat_temp = btemp_regs[1] * 0.1
     end
 
-    host.emit("battery", {
-        w      = bat_w,
-        v      = bat_v,
-        soc    = bat_soc,
-        temp_c = bat_temp,
-    })
-    host.emit_metric("battery_dc_v",   bat_v)
-    host.emit_metric("battery_temp_c", bat_temp)
+    -- A PV-only Growatt (no battery connected) still answers the battery
+    -- registers with 0, which made FTW render a phantom "Battery" node on
+    -- Overview even though no battery exists. A real battery reports a
+    -- terminal voltage and/or SoC above 0 even at rest, so treat all-zero
+    -- battery readings as "no battery present" and skip the emit.
+    --   see srcfl/ftw#1669
+    local has_battery = bat_v > 0 or bat_soc > 0 or bat_charge_w > 0 or bat_discharge_w > 0
+    if has_battery then
+        host.emit("battery", {
+            w      = bat_w,
+            v      = bat_v,
+            soc    = bat_soc,
+            temp_c = bat_temp,
+        })
+        host.emit_metric("battery_dc_v",   bat_v)
+        host.emit_metric("battery_temp_c", bat_temp)
+    end
 
     -- ---- Meter ----
 

drivers/tests/test_growatt_pv_only_battery.py

@@ -0,0 +1,107 @@
+"""A PV-only Growatt must not emit a phantom Battery stream.
+
+A Growatt with no battery connected still answers the battery Modbus
+registers with 0. The driver used to emit a `battery` stream on every poll
+regardless, which made FTW render a "Battery Growatt" node on Overview even
+though no battery exists (srcfl/ftw#1669). The driver now only emits battery
+telemetry when a battery is actually present.
+
+CI builds ./lua55 (see tools/build_luac.sh) and runs this through the host
+mock, so the guard holds in the pipeline. pytest skips it locally when the
+interpreter is absent.
+"""
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[2]
+LUA = ROOT / "lua55"
+HARNESS = ROOT / "drivers" / "tests" / "lua_harness"
+GROWATT = ROOT / "drivers" / "lua" / "growatt.lua"
+
+pytestmark = pytest.mark.skipif(
+    not LUA.exists(), reason="run make check to build ./lua55")
+
+
+def _run(body: str) -> dict[str, str]:
+    script = f'''
+package.path = "{HARNESS}/?.lua;" .. package.path
+require("host_mock")
+host.reset()
+
+{body}
+'''
+    result = subprocess.run([str(LUA), "-e", script],
+                            capture_output=True, text=True, cwd=ROOT)
+    assert result.returncode == 0, result.stdout + result.stderr
+    return dict(line.split(" ", 1)
+                for line in result.stdout.strip().splitlines() if " " in line)
+
+
+def _poll(registers: dict[str, int]) -> dict[str, str]:
+    setup = "\n".join(
+        f"host._modbus_registers.input[{addr}] = {val}"
+        for addr, val in registers.items()
+    )
+    return _run(f'''
+{setup}
+dofile("{GROWATT}")
+driver_init({{host = '127.0.0.1', port = 502, unit_id = 1}})
+local ok, err = pcall(driver_poll)
+if not ok then print("POLL_ERROR " .. tostring(err)) os.exit(1) end
+local bat = host._emitted.battery
+if bat and #bat > 0 then
+    print("BATTERY_EMITTED 1")
+    print("BAT_V " .. tostring(bat[1].v))
+    print("BAT_SOC " .. tostring(bat[1].soc))
+    print("BAT_W " .. tostring(bat[1].w))
+else
+    print("BATTERY_EMITTED 0")
+end
+''')
+
+
+def test_pv_only_install_emits_no_battery_node():
+    """A Growatt answering all-zero battery registers must not emit battery."""
+    out = _poll({})  # every register unmapped -> the mock returns 0
+    assert out["BATTERY_EMITTED"] == "0", (
+        "PV-only Growatt emitted a battery stream; Overview would show a "
+        "phantom Battery node (srcfl/ftw#1669)."
+    )
+
+
+def test_hybrid_install_with_battery_emits_battery():
+    """A real battery (voltage + SoC + charge power) must still be reported."""
+    out = _poll({
+        1009: 0, 1010: 100,   # charge power 10 W
+        1011: 0, 1012: 0,     # discharge power 0 W
+        1013: 480,            # terminal voltage 48.0 V
+        1014: 50,             # SoC 50 %
+    })
+    assert out["BATTERY_EMITTED"] == "1", (
+        "Hybrid Growatt with a battery present did not emit battery telemetry."
+    )
+    assert float(out["BAT_V"]) == 48.0
+    assert float(out["BAT_SOC"]) == 0.5
+    assert float(out["BAT_W"]) == 10.0  # charge - discharge
+
+
+def test_battery_at_rest_with_zero_soc_still_emits():
+    """A present battery reads a terminal voltage even at 0 % SoC.
+
+    Guards against an over-strict gate that would drop a real battery just
+    because its SoC register reads 0.
+    """
+    out = _poll({
+        1009: 0, 1010: 0,
+        1011: 0, 1012: 0,
+        1013: 520,            # 52.0 V present
+        1014: 0,             # SoC 0 %
+    })
+    assert out["BATTERY_EMITTED"] == "1", (
+        "A battery at 0 % SoC but with terminal voltage was dropped; the gate "
+        "must key off voltage/power, not SoC alone."
+    )
+    assert float(out["BAT_V"]) == 52.0

manifests/growatt.yaml

@@ -1,5 +1,5 @@
 name: "growatt"
-version: "2.1.2"
+version: "2.1.3"
 tier: community
 author: "Sourceful Labs AB"
 protocol: modbus
@@ -50,12 +50,12 @@ tested_devices:
     notes: "Community driver, untested"
     min_driver_version: "1.0.0"
 min_host_version: "2.0.0"
-size_bytes: 9376
+size_bytes: 9923
 dkb_id: ""
-sha256: "1e9623cbf3453697f0fba429a5b8dab7d61cf9507587e616d0cd9de3cc3594c8"
+sha256: "684c788e989c6f90b7a64fd79521f913104486f2c939bf13d4aaa2fbfddd9dad"
 signature: ""
 
 bytecode_sha256: ""
 bytecode_signature: ""
 bytecode_size: 0
-changelog: ""
+changelog: "2.1.3: skip battery telemetry when no battery is connected (PV-only installs), fixes phantom Battery node on Overview (srcfl/ftw#1669)"