diff --git a/src/pluginbattery/web.py b/src/pluginbattery/web.py
index 581e386..4cf2746 100644
--- a/src/pluginbattery/web.py
+++ b/src/pluginbattery/web.py
@@ -322,10 +322,13 @@ app = Flask(__name__)
 
 DEFAULTS = dict(
     # Window: 2025-01-01 → 2025-09-01 (8 months of dad's actual data with
-    # matching 2025 prices + solar). Net consumption over those 8 months
-    # is 1010 kWh; setting demand_kwh = 1010 gives scale factor 1.0 so the
-    # P1 series passes through unscaled.
-    demand_kwh=1010.0, retail=0.25, pv_kwp=0.0, pv_yield=875.0,
+    # matching 2025 prices + solar). The simulator scales demand by
+    # demand_kwh / ANNUAL_DEMAND_BASE; ANNUAL_DEMAND_BASE annualises the
+    # 8-month window's 1010 kWh → 1518 kWh-equivalent/yr, so set the
+    # default to 1518 to keep the per-hour P1 values unscaled (scale = 1.0).
+    # Dad's actual full-year net is 2351 kWh (from his complete CSV) — so
+    # using 1518 effectively represents 'an 8-month-extrapolated 2025 year'.
+    demand_kwh=1518.0, retail=0.25, pv_kwp=0.0, pv_yield=875.0,
     fixed_rate=False, saldering=False, eta=0.88, inflation=0.03,
     export_rate=-0.106,
 )