diff --git a/tests/infrastructure/solar/test_google_solar_api_client.py b/tests/infrastructure/solar/test_google_solar_api_client.py
index 9a38e836..450113a7 100644
--- a/tests/infrastructure/solar/test_google_solar_api_client.py
+++ b/tests/infrastructure/solar/test_google_solar_api_client.py
@@ -58,3 +58,32 @@ def test_get_building_insights_retries_on_transient_error() -> None:
     # Assert
     assert result == payload
     assert mock_get.call_count == 2
+
+
+# ---------------------------------------------------------------------------
+# Slice 3: 404 + entity-not-found raises BuildingInsightsNotFoundError
+# ---------------------------------------------------------------------------
+
+
+def test_get_building_insights_raises_on_entity_not_found() -> None:
+    # Arrange
+    client = GoogleSolarApiClient(api_key="test-key")
+
+    not_found_response = MagicMock()
+    not_found_response.status_code = 404
+    not_found_response.json.return_value = {
+        "error": {"message": GoogleSolarApiClient.ENTITY_NOT_FOUND_ERROR}
+    }
+
+    http_error = requests.exceptions.HTTPError("404")
+    http_error.response = not_found_response
+
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.raise_for_status.side_effect = http_error
+        mock_get.return_value.response = not_found_response
+
+        # Act / Assert
+        with pytest.raises(BuildingInsightsNotFoundError):
+            client.get_building_insights(longitude=-0.1278, latitude=51.5074)
+
+    assert mock_get.call_count == 1