Solar on every roof, BOI solar correction, open source section

Solar (user, 17 Oct 2026: "use as much roof space as possible")
- PV on every roof and canopy: ~640 kWp on the Payap scenario plot
  (factory roof ~523, canopies ~54, flat office roof ~65 kWp around the
  AC units); ~300 kWp on the Mueang Chi hall. Calculator: pvKWp 640,
  new pvSelf 85 % (zero export, hourly sketch), PV cost per kWp times the
  array, office-roof PV in the iso view, roofs drawn full.
- 12.8M to 16.6M THB at 20 to 26 THB/W; CSV baseline 34.37M to 56.34M;
  launch plant ~168M / 231M / 294M THB with contingency; Plan B ~216M
  (label ~215M), ~39M above Plan A; Plan A unchanged (it leases the
  array), its solar lever ~17.5M. PV payback ~4.2 to 5.9 years.
- Permits (rooftop solar no factory licence since 28 Dec 2024, ERC
  exemption under 1,000 kVA, PEA zero export) and PPA discounts sourced
  in sustainability.md.

BOI correction
- Announcement 3/2568 (in force 1 July 2025) ended BOI promotion for
  solar installations; only the battery may qualify (12M THB per MW cap).
  Removed the "BOI solar measure" from boi.md, total-investment,
  revenue-model, sustainability, site-candidates and both plan versions;
  Plan B's case for owning the array is the PPA bill it avoids
  (~0.07M USD a year).

Open source (user, 17 Oct 2026)
- digital-factory.md "Open source throughout, and working with other
  plants": everything we run and build is open source on NixOS, our code
  published (licence to decide), vendor firmware the stated exception;
  later the stack and factory-automation services for other pressing
  plants, not in the revenue.
- Business plan section 5.6 plus an executive-summary bullet, reading
  guide and not-modelled mentions; draft 0.3 rebuilt (A 60, B 61 pages),
  renders re-made with the roofs full.

docs/scale.md

@@ -298,13 +298,19 @@ small against the connection, but its own feeder and meter.
   roof plane, per the [construction RFQ](finance/phase1-construction-rfq.md)).
   This supersedes the older rule of thumb of 150 to 200 kWp on a
   ~1,500 m² building, which the massing model has overtaken
+- **Decided 17 October 2026: every roof and canopy carries PV.** On this
+  hall that is the 247 kWp roof plus the canopies' ~40 to 54 kWp, ~300
+  kWp; on the Payap scenario plot ~640 kWp, the size the investment and
+  the business plan carry
+  ([sustainability](sustainability.md#roof-design-for-pv-candidate-mueang-chi-site))
 - Northern Thailand yield ~1,400 to 1,500 kWh/kWp/yr, so 300 kWp produces
-  roughly **420 to 450 MWh/yr**
+  roughly **420 to 450 MWh/yr** and ~640 kWp ~900 to 960 MWh/yr
 - Plant consumption at mature two-shift operation: roughly **1,000 to
   1,500 MWh/yr** without electric steam, up to **~2,500 MWh/yr** with it
   (estimate), so 300 kWp covers roughly **28 to 45%** of consumption
-  without electric steam, falling to **~17%** with it; a bigger array
-  shifts that up
+  without electric steam, falling to **~17%** with it; ~640 kWp, at
+  ~85 % used on site under zero export, covers ~38 % of the launch
+  plant's ~2,000 MWh with electric steam (calculator, estimate)
 - Battery: **271 kWh** Gobel stack (ride-through, roughly
   an hour of the chiller bank's peak electrical draw; peak shaving earns
   little under PEA's time-of-use tariff, see