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Power domains and battery-backed infrastructure tiers — Demory farm site

Purpose: Tie electrical domains to which infrastructure must remain battery-backed and which can be duty-cycled — so network design ( gateways , radios ) lands on the same buses as pumps and controls . No invented wattages ; use placeholders until metered .

Doctrine package: Off-grid systems doctrine package — Demory. Power doctrine: Off-grid power doctrine — Demory farm site. Topology: Off-grid farm execution topology — Demory (Mermaid).

Naming (aligned with validation text)

Symbol Meaning
Pcrit Loads and controls that must stay up through normal cloud / WAN outages and short SOC dips (policy + engineering )**
Popt Optimistic / sheddable loads : extra RF , non-critical cameras , optional CPE , shop toys

Placeholder : P_NET_ALWAYS_W = ___ W (clamp meter ) ;** tie to Loads register.

Domains (conceptual)

```mermaid flowchart LR subgraph dc["DC domain — PV / battery native"] pv["PV strings"] bat["Battery pack"] dc_loads["DC loads — some controls, radios (policy)"] end

subgraph ac["AC domain — inverter"] pump["Pump / heavy AC"] inv_misc["Barn AC outlets"] end

pv --> bat bat --> dc_loads bat --> ac ```

Decision: Minimize inverter hours for pure DC where safe and code-compliant — cite AHJ / NEC with a PE for final design .

Battery-backed tiers

Tier What belongs Network tie-in Always-on vs duty-cycled
T0 — Life/safety policy Interlocks that must not depend on cloud Local logic / wiring first ; IP optional Always-on power path (small Wh if done right )**
T1 — Gateway spine One field gateway / MQTT aggregation Backs mesh → LAN ; buffers when WAN down Always-on by default ; measure Wh before adding second spine
T2 — Mesh / sub-GHz infra Repeaters, HaLow APs Each hop is a load on its node (solar + local battery )** Often duty-cycled (DR-1 )**
T3 — WAN CPE Starlink / LTE Egress only ; not in Pcrit unless explicitly chosen Sheddable during deep SOC

Pilot vs scale

Phase Tier focus
0–1 Prove T0 + T1 on one DC / AC segment ; meter before T2 fleet (DR-5)
Later Redundant PV / genset policy only after G1 / water / fence per business plan