A Homelab That Costs $10 a Year in Power

A homelab runs 24 hours a day, so idle power matters more than peak speed. An old rack server can cost well over $100 a year in electricity just sitting there. A small mini PC can run Home Assistant, a few containers and a file share for about $10. Here’s the math, the hardware, and the settings that get you there.

  • Homelab
  • Self-hosting
  • Hardware

The only formula you need

A device that draws 1 watt all year uses 8.76 kWh (1 W × 8,760 hours). So:

yearly cost = average watts × 8.76 × price per kWh

At $0.15 per kWh, every watt you leave on costs about $1.30 a year. A $10 budget is about 7.5 W on average. If you pay more, like many people in Europe, the same 7.5 W costs more, so cutting watts matters even more there. Plug in your own price from your electricity bill.

What typical hardware draws at idle

Idle is the number that matters, because a home server spends most of its life waiting. These are measured figures from reviews and community tests, not the manufacturers’ ratings:

DeviceIdlePer year at $0.15/kWh
Raspberry Pi 5about 3 Wabout $4
Intel N100/N150 mini PC, tunedabout 5–6 Wabout $7
Ryzen mini PC (8845HS class)about 8–15 W$10–20
Each 3.5″ hard drive, spinningabout 4–6 W$5–8
Each SSDunder 1 Wunder $1
Used rack server (Dell R720 class), OS idleabout 120 Wabout $160

The big server isn’t bad hardware. It just has two processors, redundant power supplies and a lot of fans, all built for a datacenter that pays for the electricity in bulk.

The $10 setup

  • A mini PC with an Intel N100 or N150. Four efficient cores, hardware video decoding for Jellyfin or Plex, and Proxmox idles at about 5 W on them in published tests.
  • One stick of RAM. These chips use a single memory channel. 16 GB is plenty for a handful of containers, and with RAM prices where they are in 2026, there’s no reason to buy more until you need it.
  • An NVMe SSD inside the box for the system and your data. Add hard drives only for things that really need terabytes.
  • Containers instead of virtual machines. Every VM runs its own kernel and background tasks. LXC containers in Proxmox, or Docker on plain Debian, share one and keep the CPU idle longer.

With Home Assistant and a few containers running, expect about 5–6 W. A Zigbee USB stick adds a little more. One tester measured 7–8 W with one connected. That’s right around $10 a year.

Get the idle number down

1. Check the BIOS first

Make sure C-states and ASPM (PCIe power saving) are enabled, and turn off anything you don’t use: Wi-Fi, Bluetooth, audio, extra USB controllers. Some mini PCs ship with power saving switched off to look faster in benchmarks.

2. Run powertop

powertop shows what’s keeping the machine awake, and --auto-tune switches on every power-saving option it knows about:

sudo apt install powertop
sudo powertop --auto-tune

The setting resets on reboot. To apply it at every start, create /etc/systemd/system/powertop.service:

[Unit]
Description=Powertop tunings

[Service]
Type=oneshot
ExecStart=/usr/sbin/powertop --auto-tune

[Install]
WantedBy=multi-user.target

Then enable it with sudo systemctl enable --now powertop.service.

One catch: auto-tune also lets USB devices go to sleep. If your Zigbee stick, USB disk or keyboard starts dropping out, set that one device back to “Bad” (always on) in powertop’s Tunables tab.

3. Look at the package C-states

In powertop’s Idle stats tab, the “Package” column shows how deeply the whole processor sleeps. If it rarely gets past C2 or C3, something is holding it awake. Common culprits are some network cards, SATA controllers and PCIe cards without working ASPM. You can check ASPM with:

sudo lspci -vv | grep -E "ASPM.*abled"

4. Decide what to do with hard drives

Each spinning drive costs about as much as the whole mini PC. If your data fits on SSDs, use SSDs. If it doesn’t, let the drives spin down when idle (hdparm -S), but only when they’re really idle. A drive that spins up every few minutes wears out faster and saves almost nothing.

Measure it, don’t guess

A plug-in power meter or a smart plug with energy monitoring costs about as much as a pizza and tells you the real number, including the power supply’s own losses. Measure the whole stack, not just the server. The router, switch and any UPS run all year too, and together they often draw more than the server.

Wrap-up

For a homelab, the cheapest hardware to run is usually the smallest. An N100-class mini PC with an SSD, containers instead of VMs, and five minutes in the BIOS and powertop gets you a server that costs about $10 a year to leave on. Keep the old rack server for when you need its power, or for winter heating.

Sources

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