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/finance/revenue-model.md

@@ -669,9 +669,9 @@ What it says:
 ## Operating pictures of Plan A and Plan B (October 2026)
 
 The business plan comes in two versions
-([total investment](total-investment.md#two-plans-a-at-180m-thb-and-b-at-210m-thb-october-2026)):
+([total investment](total-investment.md#two-plans-a-at-180m-thb-and-b-at-215m-thb-october-2026)):
 **Plan A** (~177M THB, the launch plant with six cost levers) and
-**Plan B** (~208M THB, the same launch plant with everything in), both
+**Plan B** (~216M THB, the same launch plant with everything in), both
 priced without contingency and with the ramp-up reserve. Both run the
 same three presses, so volume, price, direct cost, title services and
 overheads are those of the launch-plant table above; only the
@@ -679,14 +679,14 @@ depreciation follows each plan's capital (estimates):
 
 - **Plan A**: the high end of its blocks (6.25M USD) over 10 years, the
   midpoint (4.90M USD) over 12.5, the low end (3.56M USD) over 15. The
-  solar PPA adds its power price to the energy line (~0.03M USD a year in
-  the calculator), not shown here.
-- **Plan B**: 7.47M USD over 10 years, 5.84M over 12.5, 4.22M over 15.
-  Its owned solar saves the PPA power bill; cassette and CD-R sales, tours
+  solar PPA adds its power price to the energy line (~0.07M USD a year in
+  the calculator for the ~640 kWp array), not shown here.
+- **Plan B**: 7.73M USD over 10 years, 6.08M over 12.5, 4.42M over 15.
+  Its owned solar (~640 kWp, every roof and canopy) saves the PPA power bill; cassette and CD-R sales, tours
   and the Payap programmes it opens from the start are not modelled.
 - **Payback** is counted on the whole plan price including the ramp-up
-  reserve (Plan A 3.86M / 5.35M / 6.85M USD, Plan B 4.52M / 6.30M /
-  8.07M USD from the low to the high end).
+  reserve (Plan A 3.86M / 5.35M / 6.85M USD, Plan B 4.72M / 6.53M /
+  8.34M USD from the low to the high end).
 
 | USD/yr | A adverse | A central | A favourable | B adverse | B central | B favourable |
 |---|---|---|---|---|---|---|
@@ -697,10 +697,10 @@ depreciation follows each plan's capital (estimates):
 | Title-services contribution | 0.07M | 0.23M | 0.48M | 0.07M | 0.23M | 0.48M |
 | Cash overheads | 0.45M | 0.33M | 0.20M | 0.45M | 0.33M | 0.20M |
 | **EBITDA** | **0.23M** | **1.73M** | **3.79M** | **0.23M** | **1.73M** | **3.79M** |
-| Depreciation | 0.62M | 0.39M | 0.24M | 0.75M | 0.47M | 0.28M |
-| **Operating profit** | **-0.39M** | **1.34M** | **3.55M** | **-0.52M** | **1.26M** | **3.51M** |
+| Depreciation | 0.62M | 0.39M | 0.24M | 0.77M | 0.49M | 0.29M |
+| **Operating profit** | **-0.39M** | **1.34M** | **3.55M** | **-0.54M** | **1.24M** | **3.50M** |
 | Revenue | 2.28M (~75M THB) | 3.65M (~120M THB) | 5.41M (~179M THB) | 2.28M (~75M THB) | 3.65M (~120M THB) | 5.41M (~179M THB) |
-| Payback on the plan price (EBITDA, mature year) | ~30 yr | ~3.1 yr (2.2 to 4.0) | ~1.0 yr | ~35 yr | ~3.6 yr (2.6 to 4.7) | ~1.2 yr |
+| Payback on the plan price (EBITDA, mature year) | ~30 yr | ~3.1 yr (2.2 to 4.0) | ~1.0 yr | ~36 yr | ~3.8 yr (2.7 to 4.8) | ~1.2 yr |
 
 What it says:
 
@@ -708,14 +708,16 @@ What it says:
   year**; its adverse corner still loses money, because it would need
   ~0.9 million records to cover depreciation and the three presses make
   0.58 million at that rate.
-- **Plan B** breaks even at **~0.23 million records**, and its adverse
+- **Plan B** breaks even at **~0.24 million records**, and its adverse
   corner loses more (~1.1 million records needed to cover depreciation).
   At the central cost and volume the price that covers its depreciation
-  is ~2.8 USD (~91 THB) a record.
-- **On these numbers Plan B's extra ~31M THB earns nothing**: the same
-  EBITDA, more depreciation and a longer payback. Its case rests on what
-  the table leaves out: the BOI solar measure on the owned array, the
-  PPA power bill it avoids, full stamper metrology from the first
+  is ~2.8 USD (~92 THB) a record.
+- **On these numbers Plan B's extra ~39M THB earns little**: the same
+  EBITDA here (the calculator, which splits energy by plan, puts it ~0.07M
+  USD a year ahead for the PPA bill the owned array avoids), more
+  depreciation and a longer payback. Its case rests on what
+  the table leaves out: the PPA power bill it avoids (the BOI no longer
+  promotes solar installations since July 2025), full stamper metrology from the first
   release, tours, the Payap programmes, and cassette and CD-R sales.
 - **The caveats above hold for both:** a central EBITDA margin of ~47 %
   is far above the 15 to 25 % pressing plants earn, the cost of specials
@@ -724,10 +726,10 @@ What it says:
 
 The [calculator](../fleet-calculator.html) presets, at the team's
 planning rates (3 records a minute per Duplex system) and its own cost
-build-up, give at 850k records: **Plan A** EBITDA 2.04M USD, payback 2.4
+build-up, give at 850k records: **Plan A** EBITDA 2.05M USD, payback 2.4
 years on the investment, cash payback in year ~3.9 and ~25 % IRR over ten
-years with the reserve in year 0; **Plan B** EBITDA 2.07M USD, payback 2.8
-years, cash payback in year ~4.3 and ~21 % IRR (pre-tax, pre-financing,
+years with the reserve in year 0; **Plan B** EBITDA 2.12M USD, payback 2.9
+years, cash payback in year ~4.4 and ~21 % IRR (pre-tax, pre-financing,
 estimates).
 
 ## Operating picture at full capacity (five-press fleet)