Smart Home

DC Smart Home: When the Muscles Fail, the Brain Stays Awake

Smarthome Team

16 Dec 2025 • 6 min read

At our core, we are doing fine.

3 AM, the Storm, and the Water

Imagine the following scenario:

An autumn storm sweeps across the region. At 3 AM, the power grid fails. Your inverter - normally reliable - happens to have a defect today and can't manage the switchover to island mode. The house is dark and silent.

Somewhere in the basement, the storm has caused a water pipe to burst. Water is flowing.

In a conventional smart home, what happens now is: Nothing. The water leak sensor is dead. The shutoff valve controller is dead. The server is dead. You sleep on while your basement floods.

In our installation, something different happens:

The water leak sensor - battery-free but DC-powered - detects the water. The WHIP Hub processes the signal. The shutoff valve - also DC-powered - closes. Your smartphone vibrates: "Water leak in basement. Main valve closed."

You can't pump (the pump needs 230 V). But the damage is contained. The house acted even though it "had no power."

The Principle: Brain and Muscles

A house has two types of systems: Those that know - and those that do.

The smart home can be divided into two categories:

The Brain - systems that perceive and process:

Sensors (temperature, humidity, motion, leakage)
Processing units (hubs, servers)
Communication (network, notifications)

The Muscles - systems that act:

Pumps (heating, water)
Motors (blinds, garage door)
High-power actuators (heat pump, air conditioning)

Unlike its biological counterpart - which consumes a full 20% of our metabolic energy - the house brain is modest. Sensors consume milliwatts in normal operation. A hub perhaps 5 watts. Even a server cluster manages with 50-100 watts.

The muscles, on the other hand, are hungry. A circulation pump draws several hundred watts. A heat pump several kilowatts.

Our conclusion: The entire brain runs on DC, directly from the battery storage. The muscles run on 230 V AC. When the inverter fails, the house loses its muscles - but not its mind.

The Three Layers of the DC Brain

In our flagship installation, we implemented this consistently:

Battery Storage (48V)
        │
        ├── Inverter ── 230V AC ── "Muscles"
        │                              │
        │                              ├── Circulation pumps
        │                              ├── Heat pump
        │                              └── Motors, e.g., blinds
        │
        └── DC Infrastructure ── "Brain"
              │
              ├── Victron Orion 48/24 ── Server Cluster (~20V)
              │                              │
              │                              ├── NUC 1 (Proxmox)
              │                              ├── NUC 2 (Proxmox)
              │                              └── NUC 3 (Proxmox)
              │                                    │
              │                                    └── VMs (WHIP Server, HA, ...)
              │
              ├── DC/DC ── WHIP Hubs (local processing)
              │
              └── DC/DC ── WHIP Nodes + DC Actuators
                              │
                              ├── Sensors (temperature, leakage, ...)
                              └── Control valves (24V)

Three layers, all DC-powered:

WHIP Nodes - The sensory organs. Sensors for temperature, humidity, water leakage, door/window contacts. Plus small DC actuators like control valves.
WHIP Hubs - The cerebellum. Local processing, automation logic, communication with nodes. Can react autonomously, even when the server is offline.
Server Cluster - The cerebrum. Central intelligence, long-term storage, complex automations, user interface.

The NUC Cluster: Triple Protected

The heart of our "brain" is a 3-node Proxmox cluster. Three Intel/ASUS NUCs running in HA (High Availability) mode. If one node fails, the others take over. Classic server redundancy.

But NUCs have a peculiarity: They require exactly 19-20 V input voltage (maximum 22 V). Not 12 V like many embedded systems. Not 24 V like the industrial standard. But something in between.

The solution: A Victron Orion 48/24 DC/DC converter, trimmer-adjusted to exactly 20 V. Not "approximately suitable," but precisely what the NUCs expect.

But the Orion delivers more than just the right voltage. It provides galvanic isolation. This means: The battery voltage (which fluctuates between 42 and 58 V) has no electrical contact with the server cluster. Overvoltages, transients, interference - they end at the Orion.

Power Grid (230V AC)
    │
    ╳ Galvanic Isolation (Inverter)
    │
    ▼
Battery Storage (48V, fluctuating 42-58V)
    │
    ╳ Galvanic Isolation (Victron Orion)
    │
    ▼
Server Cluster (20V, stable, isolated)

Zeus himself could hurl a lightning bolt at the house. It would be stopped at the inverter (assuming the lightning protection failed). If it somehow got through, it would be stopped at the Orion. The server cluster lives in its own isolated electrical world.

Why DC/DC is more reliable than DC/AC:

An inverter is a complex device: grid synchronization, reactive power management, elaborate control, many power semiconductors. A Swiss long-term study showed a 34% failure rate for residential inverters over 15 years. In large PV installations, inverters cause 50-60% of all failures.

A DC/DC converter is simpler: fewer components, simpler topology, no grid connection. High-quality DC/DC converters achieve MTBF values of over one million hours - mathematically over 100 years. An order of magnitude more than typical inverters.

What isn't there can't fail. The house brain hangs on the more reliable path.

The result: Hardware redundancy plus power supply resilience. One node can fail - the system keeps running. The inverter can fail - the system keeps running. Both at the same time? The system still runs.

Practical Scenarios

Scenario 1: Water Leak

The classic: A hose bursts, a seal fails, water flows.

Without DC Smart Home:

Leak sensor detects water
Sends signal to central unit
Central unit controls solenoid valve
All good - as long as there's power

With DC Smart Home during power outage:

Leak sensor (DC) detects water
WHIP Hub (DC) processes signal
Shutoff valve (DC) closes
Notification goes out (DC network)
Damage contained, even without 230 V

The pump for draining doesn't work (230 V). But the most important thing - stopping the water inflow - works.

Scenario 2: Heating Monitoring in Winter

Power outage at -15°C. The heat pump is stopped. The circulation pumps are stopped. The house is cooling down.

Without DC Smart Home:

You know nothing. When power returns, it might be too late. Frozen pipes, water damage.

With DC Smart Home:

Temperature sensors (DC) report: "Living room 12°C and falling"
Server (DC) calculates: "At current cooling rate, critical temperature in 4 hours"
Notification: "Heating failure. Take action."
Zone valves (DC): Can isolate critical areas

You can't heat. But you know what's happening. You can react - ask neighbors to connect a space heater, protect at least the most critical rooms.

The Uncanny Valley Experience (Part 3)

In our articles about SELV-DALI and DC Network, we described the strange feeling when things keep working during a power outage that shouldn't be working.

With DC Smart Home, this feeling reaches a new dimension:

The inverter is off. The 230 V grid is dead.

The heating isn't running
The refrigerator is silent
The washing machine doesn't respond

But:

Your smartphone shows: "Living room 21.3°C, trend falling"
The garden camera streams live
The motion detector reports: "Cat in hallway"
The system continues logging all events

The house can no longer act in a big way. But it still knows everything. It still sees everything. It still thinks.

It's as if you paralyzed a person's arms and legs - but their brain continues to work perfectly clearly. They can speak, see, hear, analyze. Just not act.

After a while, this feels right. A house that goes completely blind during a power outage then feels like a design flaw.

System Limitations

Honesty matters: Not everything can be DC.

These muscles need 230 V AC:

System	Typical Power	DC Alternative?
Heat pump	2,000-5,000 W	No
Circulation pumps	50-100 W	Theoretically yes, practically rare
Blind motors	100-300 W	Rarely available
Washing machine	2,000+ W	No
Electric stove	3,000-10,000 W	No

Physical reality: High power at low voltage means high currents. High currents mean thick cables, high losses, expensive components.

For sensors and controls, DC is perfect. For high-power actuators, 230 V AC remains the pragmatic choice.

But: Most smart home scenarios don't need high power. They need information and small interventions:

Knowing there's a problem ✓
Closing a valve ✓
Sending a notification ✓
Logging a status ✓

All of this works with a few watts. All of this can be DC.

Summary

The traditional smart home has a fundamental design flaw: It mixes brain and muscles in the same power supply. When the muscles fail, the brain dies too.

Our solution separates the two:

The brain on DC - Sensors, hubs, server, network - all directly on battery storage
The muscles on AC - Pumps, motors, high-power devices - on the inverter
Intelligent DC actuators - Small interventions (valves) possible even without AC

The result: A house that even in the worst case - grid failure plus inverter defect - still knows what's happening. That can still communicate. That can still make small but decisive interventions.

The muscles may fail. But the brain stays awake.

This article is part of our case study series about the WHIP flagship installation. More articles: SELV-DALI: Light Without the Grid, DC Network: The Control Paradox

Technical Specifications:

Battery storage: 48 V nominal (LiFePO4)
Server cluster: 3× Intel NUC, Proxmox HA, ~20 V via Victron Orion
WHIP Hubs: 12 V DC (directly from V_bat)
WHIP Nodes: 3.3/5V (directly from V_bat or 24V)
DC actuators: Control valves 24 V, shutoff valves 12/24 V
Galvanic isolation: Two-stage (inverter + Orion)