diff --git a/pycheckwatt/__init__.py b/pycheckwatt/__init__.py
index 00105ab..d50ce4e 100644
--- a/pycheckwatt/__init__.py
+++ b/pycheckwatt/__init__.py
@@ -755,21 +755,38 @@ async def get_ems_settings(self, rpi_serial=None):
     async def get_price_zone(self):
         """Fetch Price Zone from CheckWatt."""
 
+        serial = self.rpi_serial
+        if not serial:
+            _LOGGER.error("Cannot fetch price zone without an RPi serial")
+            return False
+
         try:
-            endpoint = "/ems/pricezone"
+            endpoint = f"/site/Statuses?serial={serial}"
             # Define headers with the JwtToken
             headers = {
                 **self._get_headers(),
                 "authorization": f"Bearer {self.jwt_token}",
             }
 
-            # First fetch the revenue
+            # The site status contains the market bidding area (price zone).
             async with self.session.get(
                 self.base_url + endpoint, headers=headers
             ) as response:
                 response.raise_for_status()
                 if response.status == 200:
-                    self.price_zone = await response.text()
+                    statuses = await response.json()
+                    if (
+                        not isinstance(statuses, list)
+                        or not statuses
+                        or not isinstance(statuses[0], dict)
+                    ):
+                        _LOGGER.error("Invalid site status response for price zone")
+                        return False
+                    price_zone = statuses[0].get("Mba")
+                    if not isinstance(price_zone, str) or not price_zone.strip():
+                        _LOGGER.error("Site status contains no valid price zone")
+                        return False
+                    self.price_zone = price_zone.strip()
                     return True
 
                 _LOGGER.error(
@@ -790,7 +807,8 @@ async def get_spot_price(self):
             end_date = datetime.now() + timedelta(days=1)
             to_date = end_date.strftime("%Y-%m-%d")
             if self.price_zone is None:
-                await self.get_price_zone()
+                if not await self.get_price_zone():
+                    return False
             endpoint = f"/ems/spotprice?zone={self.price_zone}&fromDate={from_date}&toDate={to_date}"  # noqa: E501
             # Define headers with the JwtToken
             headers = {
diff --git a/tests/unit/test_price_zone.py b/tests/unit/test_price_zone.py
new file mode 100644
index 0000000..7bafe46
--- /dev/null
+++ b/tests/unit/test_price_zone.py
@@ -0,0 +1,94 @@
+"""Regression coverage for price zones obtained from site statuses."""
+
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+from aiohttp import ClientResponseError
+
+from pycheckwatt import CheckwattManager
+
+
+@pytest.fixture
+def manager():
+    manager = CheckwattManager("test_user", "test_pass")
+    manager.customer_details = {"Meter": [{"RpiSerial": "abc123"}]}
+    manager.jwt_token = "test-token"
+    manager.session = Mock()
+    return manager
+
+
+def mock_response(manager, payload):
+    response = Mock(status=200)
+    response.json = AsyncMock(return_value=payload)
+    context = manager.session.get.return_value
+    context.__aenter__ = AsyncMock(return_value=response)
+    context.__aexit__ = AsyncMock(return_value=False)
+    return response
+
+
+@pytest.mark.asyncio
+async def test_site_status_zone_is_used_for_spot_prices(manager):
+    response = mock_response(manager, None)
+    prices = {"Prices": [{"Price": 0.42}]}
+    response.json.side_effect = [[{"Mba": "SE3"}], prices]
+
+    assert await manager.get_spot_price() is True
+    assert manager.price_zone == "SE3"
+    assert manager.spot_prices == prices
+    requests = manager.session.get.call_args_list
+    assert len(requests) == 2
+    assert requests[0].args[0] == (
+        "https://api.checkwatt.se/site/Statuses?serial=ABC123"
+    )
+    assert requests[0].kwargs["headers"]["authorization"] == "Bearer test-token"
+    assert (
+        requests[1]
+        .args[0]
+        .startswith("https://api.checkwatt.se/ems/spotprice?zone=SE3&")
+    )
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "payload",
+    [
+        None,
+        {},
+        [],
+        [None],
+        [{}],
+        [{"Mba": None}],
+        [{"Mba": ""}],
+        [{"Mba": "  "}],
+        [{"Mba": 3}],
+    ],
+)
+async def test_invalid_zone_stops_spot_price_request(manager, payload):
+    mock_response(manager, payload)
+
+    assert await manager.get_spot_price() is False
+    assert manager.price_zone is None
+    manager.session.get.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_missing_serial_does_not_send_request(manager):
+    manager.customer_details = {"Meter": []}
+
+    assert await manager.get_price_zone() is False
+    manager.session.get.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_http_failure_stops_spot_price_request(manager):
+    response = mock_response(manager, None)
+    response.raise_for_status.side_effect = ClientResponseError(
+        request_info=Mock(real_url="https://api.checkwatt.se/site/Statuses"),
+        history=(),
+        status=404,
+    )
+
+    assert await manager.get_spot_price() is False
+    assert manager.price_zone is None
+    manager.session.get.assert_called_once()
+    response.json.assert_not_awaited()