OFF-GRID BUILD BLUEPRINT

SYSTEM AT A GLANCE

The full pipeline — photons in, radio waves out

STRING ACCOUNTING — SINGLE SOURCE OF TRUTH

1 string = 2× 24V/400W panels in series (~48V nominal, ~95–100V Voc)

MPPT ceiling is 45A PV short-circuit input per unit = 4 strings (8 panels) max — the input-current limit, not just wattage. NEVER 3 panels per string: 150V Voc max in frost.

LOCKED HARDWARE

Decision tree closed 2026-11-06 · audited same day

WHAT CHANGED SINCE THE CHEMISTRY PAGE

Chemistry conclusion survived the audit — the hardware plan evolved

• Chemistry: LiFePO4 still the winner (matches the v1 table). Only the vendor changed: Deye SE-F16 → DatouBoss 48V/314Ah at ~€119/kWh — same 16 kWh class, 210A BMS, ~€5,700 total vs €8,955 planned.
• MPPT: SmartSolar family swapped for BlueSolar (identical electricals, Bluetooth removed) — broadcast-site + home RF hygiene, biological considerations.
• Topology: shared battery bus chosen; escape hatch to 1-pack-per-Studer is rewiring only, no hardware swap.
• Transmission: combiner doctrine added — string fuses + main DC breaker + T2 SPD at the array, one 25 mm² bundle per MPPT over the 30m run, 8 conductors in the trench instead of 16.
• Audit fixes folded in: string ceiling = 32 panels (not 24), winter doubled-array yield ~19–20 kWh/day @ 24 panels, busbar trunk upsized for ~500A aggregate (2× 95 mm² or 120–150 mm²).

20-YEAR COST — UPDATED FOR DATOUBOSS

Normalized to ~43 kWh usable · replacements included

The vendor swap didn't change the chemistry conclusion — it improved it by ~37%. Flooded still ends the 20-year race at ~10× the DatouBoss cost.

EXPANSION ROADMAP

Growth without hardware regret — every stage reuses the fleet

• Stage 1 — baseline: 16 panels, 3 packs, 4 MPPTs. 43 kWh usable, clean 2/2/2/2 string loading. Winter baseline ~10 kWh/day.
• Stage 2 — doubling: +8 panels → 24 total, 3 strings per MPPT. Winter ~19–20 kWh/day, full bank recovery in bad weather. No controller change; resize combiner breakers/fuses FIRST.
• Stage 3 — ceiling: 32 panels on the same 4 MPPTs = ~20% midday clipping. Above 32 panels: +2× 150/45s (6 total, 19.2 kW). Escape hatches everywhere: spare PV ceiling (10.4→19.2 kW), parallel pack slots (up to 15), battery layout switchable by rewiring.

BUILD CHECKLIST

Live from PROJECT-CONTEXT.md v7 · tick as Avantida goes dark-grid

• Confirm daily consumption (kWh) via Studer logs/meter
• Order 3× DatouBoss 48V 314Ah (verify sale variant at checkout)
• Order 4× BlueSolar MPPT 150/45 (verify VE.Direct port; Skroutz quote)
• Combiner gear baseline: 8× 15A gPV fuses, 4× 25–32A DC breakers, 4× T2 SPDs
• EMC parts: sendust toroids, MnZn rings, clamp-on split ferrites
• Copper: 4× 25 mm² bundles (30m), 95 mm² Studer taps, 2× 95 mm² trunk
• Busbar + per-pack Class-T fusing layout
• Bulkhead entry plate (single penetration, bonded)
• Earth array frames + earth rod; mount combiner boxes
• Top-balance 3 packs → parallel onto shared bus
• Tune Studer profiles (abs 56.0V / float 54.0V)
• Pull 30m bundles → terminate at MPPTs (pigtails at terminals)
• Mount MPPTs >2m from receiver racks
• Baseline SDR sweep → chokes/filters → re-sweep verify
• Future: double PV — resize combiner protection first