Model/datatypes/epc/surveys
Khalim Conn-Kowlessar 9521d52403 S0380.234: PV diverter (Appendix G4) — diverts surplus PV to the cylinder
SAP 10.2 Appendix G4 (PDF p.72-73). A PV diverter routes surplus PV
generation (the would-be export EPV,m × (1 − βm)) to an immersion heater
in the hot-water cylinder. Per G4 step 4:

    SPV,diverter,m = EPV,m × (1 − βm) × 0.8 × fPV,diverter,storageloss

(0.8 = cylinder heat-acceptance; fPV,diverter,storageloss = 0.9 for the
higher storage temperature), clamped to ≤ (62)m + (63a)m, and entered as
the negative worksheet (63b)m (step 5). The β factor is computed on the
PRE-diverter (219) per the §3a note (lines 5485-5486). Effects:
  - (64)m = (62)m + (63b)m → less main-system water-heating fuel (219);
  - export drops to EPV,ex,m = EPV,m(1 − βm) + (63b)m / 0.9 (§4 p.94
    line 5501); the onsite dwelling portion EPV,m × βm is unchanged.

Inclusion (G4 step 1) requires ALL of: a PV system connected to the
dwelling; a cylinder larger than (43) average daily HW use; no solar
water heating; no battery — else the diverter is disregarded.

Three layers:
  - extractor reads Summary §19 "Diverter present"; schema 21.0.0/21.0.1
    SapEnergySource gains `pv_diverter` (API `sap_energy_source.pv_diverter`);
  - `Renewables.pv_diverter_present` + domain `SapEnergySource.pv_diverter_present`,
    set in both the Elmhurst and API mapper paths;
  - `_pv_diverter_monthly_kwh` applies the G4 math after the β split;
    `cert_to_inputs` recomputes (219) and the PV export.

On simulated case 19 (electric storage heaters, 7-hour, PV + diverter):
SAP continuous 50.33 → 51.34 (worksheet 51.2221; both round to the
lodged 51), cost (255) 1847.5 → 1812.3 (ws 1816.6), CO2 (272) 3331 →
3120 (ws 3126), with (233a) dwelling 1280.6 (ws 1280.4). The residual
+0.11 SAP is an upstream winter Appendix-M monthly-EPV-shape gap +
fabric (33) +1.0, tracked as the next case-19 cause. Suite: 2412 pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-04 22:59:12 +00:00
..
tests Handle wall thickness "Unmeasurable" 🟩 2026-04-30 16:41:16 +00:00
__init__.py pashub rdsap sitenotes pdf output to dataclasses 2026-04-13 11:35:02 +00:00
elmhurst_site_notes.py S0380.234: PV diverter (Appendix G4) — diverts surplus PV to the cylinder 2026-06-04 22:59:12 +00:00
pashub_rdsap_site_notes.py Handle wall thickness "Unmeasurable" 🟩 2026-04-30 16:41:16 +00:00