diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index af90f142f..5d0c165c0 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -74,6 +74,54 @@ class TestRoofConstructionTypeCoding:
         assert extension_part.roof_construction_type == "Flat"
 
 
+class TestPhotovoltaicArrayMapping:
+    """A surveyed per-system PV block ("PV 1: kWp value: 2.43 kWp", pitch 30°,
+    orientation "South East", overshading "None or very little") must reach
+    `sap_energy_source.photovoltaic_arrays` — the ONLY field the calculator's
+    Appendix M generation path reads. Dropping it silently zeroes the PV credit
+    (issue #1590 bug 1; fixture 507639151843 under-rates by 13.6 SAP).
+    """
+
+    def test_surveyed_pv_array_reaches_photovoltaic_arrays(self) -> None:
+        # Arrange — the survey's PV block: 2.43 kWp, 30°, SE, no overshading.
+        data = load("pashub_rdsap_site_notes_example1.json")
+        data["renewables"]["photovoltaic_array"] = True
+        data["renewables"]["pv_arrays"] = [
+            {
+                "kwp": 2.43,
+                "pitch_degrees": 30,
+                "orientation": "South East",
+                "overshading": "None or very little",
+            }
+        ]
+        survey = from_dict(PasHubRdSapSiteNotes, data)
+
+        # Act
+        result = EpcPropertyDataMapper.from_site_notes(survey)
+
+        # Assert — SAP codes: pitch 30° → 2, "South East" → octant 4,
+        # "None or very little" → 1 (ZPV=1.0).
+        arrays = result.sap_energy_source.photovoltaic_arrays
+        assert arrays is not None
+        assert len(arrays) == 1
+        assert arrays[0].peak_power == 2.43
+        assert arrays[0].pitch == 2
+        assert arrays[0].orientation == 4
+        assert arrays[0].overshading == 1
+
+    def test_no_pv_block_keeps_arrays_absent(self) -> None:
+        # Arrange — the fixture as lodged (no PV).
+        survey = from_dict(
+            PasHubRdSapSiteNotes, load("pashub_rdsap_site_notes_example1.json")
+        )
+
+        # Act
+        result = EpcPropertyDataMapper.from_site_notes(survey)
+
+        # Assert
+        assert result.sap_energy_source.photovoltaic_arrays is None
+
+
 class TestRoofInsulationNoneCoding:
     """A surveyed roof-space "Insulation At: None" is the assessor explicitly
     recording ZERO loft insulation — `from_site_notes` must lodge an explicit
diff --git a/datatypes/epc/surveys/pashub_rdsap_site_notes.py b/datatypes/epc/surveys/pashub_rdsap_site_notes.py
index 583eb228d..ba629f41e 100644
--- a/datatypes/epc/surveys/pashub_rdsap_site_notes.py
+++ b/datatypes/epc/surveys/pashub_rdsap_site_notes.py
@@ -222,6 +222,19 @@ class Conservatories:
     has_conservatory: bool
 
 
+@dataclass
+class PvArrayDetail:
+    """One surveyed PV array from the Renewables section's per-system block
+    ("PV {n}: kWp value / Photovoltaic Pitch / Orientation / Overshading").
+    Raw survey labels for orientation/overshading — coding to SAP ints happens
+    at the mapper boundary (ADR-0015)."""
+
+    kwp: Optional[float] = None
+    pitch_degrees: Optional[int] = None
+    orientation: Optional[str] = None
+    overshading: Optional[str] = None
+
+
 @dataclass
 class Renewables:
     wind_turbines: bool
@@ -231,6 +244,8 @@ class Renewables:
     hydro: bool
     pv_connection: Optional[str] = None
     percent_roof_covered_pv: Optional[int] = None
+    pv_diverter_present: Optional[bool] = None
+    pv_arrays: Optional[List[PvArrayDetail]] = None
 
 
 @dataclass