---
title: "Hardware & power, explained | Nexus Observatory"
description: "Interactive explainer: hardware & power in 3D, chapter by chapter: the battery is sized for the night, the array for the shortest day…"
url: https://observatory.global/hardware/explainer/
publisher: Nexus Observatory Inc.
updated: 2026-10-28
---

**12:00** *· 2.32 kW from the array* 

**Battery 100 %** 

**Load** *· 400 W* 

**24 hours** *· array output, load, battery charge* 

**57.7 °C inside** *· 35 °C outside* 

**Heat exchanger** *· 136 W* 

**Drop 0.60 m** *· stops within 54 mm* 

**Isolators** *· fn 10.1 Hz* 

**Vehicle floor** *· input vibration* 

**Sensor** *· 6.6 W at the device* 

**Camera** *· 26.4 W at the device* 

**Access point** *· 52.8 W at the device* 

**PTZ camera** *· 75.0 W at the device* 

**PoE switch** *· 24 ports* 

**227 N** *· at 15 m* 

**3.40 kN·m** *· added at the base* 

**Wind profile** *· 29.5 m/s at 3 m, 40.3 m/s at 27 m* 

**Alternator** *· 60 A at 14 V* 

**Load** *· 120 W* 

**Battery 26 %** *· 12:00, parked* 

**LFP battery and inverter** 

01

02

03

04

05

06

Intro.

Hardware & power · Explainer

# Equipment that runs where the grid and the weather do not help.

Six engineering checks behind every field installation, each worked live: the solar and battery balance through a day and a night, the heat an enclosure can shed, the isolation that protects a transit rack, the Power over Ethernet budget, the wind on a mounted antenna and the power a crew truck carries. Every number below is computed live from your inputs.

**01** Microgrid energy balance

**02** Enclosure thermal

**03** Rugged rack isolation

**04** PoE budget

**05** Mounting and wind load

**06** Mobile power

**01** · Microgrid energy balance

## The battery is sized for the night, the array for the shortest day.

Daily irradiation outside the atmosphere follows from latitude and date: H₀ = (24 · 3600 · Gsc / π)(1 + 0.033 cos(360n/365))(cos φ cos δ sin ωs + ωs sin φ sin δ), with sunset hour angle ωs = arccos(−tan φ tan δ). The clearness index takes it to the ground, and the array delivers its rated kilowatts times that irradiation times a performance ratio of 0.8, shaped hour by hour by the Sun's height. The battery carries the load through the dark on 90 % of its capacity.

Date

Sky

**Day length**: 16 h 19 min
**Irradiation on the ground**: 5.80 kWh/m²
**PV energy · load energy a day**: 23.2 · 9.6 kWh
**Daily balance**: +13.6 kWh
**Hours of autonomy on the battery**: 33.8 h
**Lowest charge over the cycle**: 74 %

**02** · Enclosure thermal

## A sealed box sheds heat only through its skin.

A free-standing painted steel enclosure loses heat through every face but its base, A = WD + 2H(W + D), at about 5.5 W/m²K, so the inside runs ΔT = P / (5.5 A) above ambient. A sealed IP66 / NEMA 4X box that runs too hot needs a closed-loop exchanger or air conditioner for the difference, P − 5.5 A (Tmax − Tamb). A filtered-fan IP54 box moves V = 3.1 (P − 5.5 A ΔT) / ΔT m³/h of outside air, and no fan can cool below ambient. Equipment here is held at 50 °C or less.

Enclosure, W × H × D

Protection

**Effective surface**: 3.20 m²
**Rise from the skin alone**: 22.7 K
**Inside, sealed and uncooled**: 57.7 °C
**Closed-loop cooling needed**: 136 W

**03** · Rugged rack isolation

## Isolators trade rattle for sway space.

The inner rack frame rides on eight elastomer isolators, a mass on a spring with natural frequency fn = (1/2π)√(k/m). Above √2 times fn the isolators cut vibration: transmissibility is √((1 + (2ζr)²) / ((1 − r²)² + (2ζr)²)) with r = f / fn and damping ζ = 0.1. In a drop the frame meets the case at v = √(2gh); the isolators stop it within v / ωn at a peak of v ωn / g. Softer isolators protect better and need more room to move.

**Natural frequency**: 10.1 Hz · ratio 2.98
**Transmissibility**: 0.15 · −16.6 dB
**Impact speed**: 3.43 m/s
**Sway space needed**: 54 mm
**Peak on the equipment**: 22.1 g

**04** · Power over Ethernet budget

## The switch allocates by class, the cable takes its share.

A PoE switch reserves each port's class power from its supply: 7 W for a class 2 sensor, 30 W for a class 4 camera, 60 W for a class 6 access point and 90 W for a class 8 pan-tilt camera with a heater. The cable burns I²R on the way: at 44 V and 20 Ω for 802.3af, 50 V and 12.5 Ω for 802.3at, and two pair-sets in parallel at 50 or 52 V for 802.3bt, scaled by length from 100 m. Ports are powered in order until the supply is spent; the rest stay dark.

Switch PoE supply

**Ports used of 24**: 15
**Allocated · left**: 328 W · 42 W
**Lost in the cables**: 37.6 W
**At a class 8 camera**: 75.0 W of 90 W
**Devices left unpowered**: 2

**05** · Mounting and wind load

## Wind load grows with the square of speed, and speed grows with height.

Wind speed rises with height by the power law v(h) = v₁₀ (h / 10)1/7 over open ground. The dynamic pressure is q = ½ρv² with ρ = 1.225 kg/m³, and the drag on the equipment is F = q Cd A, with Cd about 1.2 for a flat panel facing the wind and 1.4 for a solid dish without a radome or a sector antenna face-on. The force acts at the mount, so the bending moment it adds at the tower base is F · h.

Equipment

**Projected area · Cd**: 0.224 m² · 1.2
**Wind at the mount**: 37.1 m/s
**Dynamic pressure**: 842 Pa
**Drag on the equipment**: 227 N
**Moment at the tower base**: 3.40 kN·m

**06** · Mobile power

## A truck is a generator that has to keep driving.

A DC-DC charger draws the alternator's spare current at 14 V into a lithium iron phosphate battery at 95 % efficiency; an inverter at 90 % efficiency runs the load around the clock. Charging power is 14 I × 0.95, the battery runs the load for 0.9 E η / P hours, and the day balances when the hours of driving put back what the load takes. The scene plays one day in 24 seconds, driving first.

**Charging power**: 798 W
**Empty to full**: 3 h 23 min
**Load run time on the battery**: 20 h 15 min
**Energy in · out a day**: 2.39 · 3.20 kWh
**Extra engine hours to balance**: 1 h 01 min

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