7 ways to cut your homelab electricity bill (without killing uptime)

Every few weeks someone on r/homelab posts a power bill that made them rethink the whole rack. The fix is almost never “turn it all off” — it’s shaving idle watts off the gear you keep running. Here are seven changes that actually move the needle, roughly in order of impact.

The short answer: attack idle draw, because always-on gear lives at idle. Consolidate onto one efficient host, enable C-states, spin down idle drives, right-size the PSU, kill idle GPU draw, schedule non-critical machines off, and measure first. Each watt you remove saves about $1.49/year at $0.17/kWh — small per watt, large in aggregate.

What a watt is worth

Before optimizing, know the exchange rate. Running one watt continuously for a year costs:

Source: electricity prices, data as of 2026-06-14.

So a 30 W cut is worth ~$45/year in the US and ~€105/year in Germany. That framing tells you which changes are worth the effort.

1. Consolidate onto one efficient host (biggest win)

The classic mistake is running a power-hungry old server 24/7 for workloads a tiny box would handle. A modern Intel N100 mini-PC idles around 7 W and runs Proxmox, Docker and a dozen services comfortably. Moving from a 110 W rack server to a 10 W mini-PC saves roughly 100 W — about $149/year in the US, €350/year in Germany. That’s frequently more than the mini-PC costs.

2. Enable CPU C-states

Disabled or shallow C-states are shockingly common on used enterprise boards and some mini-PC BIOSes, and they silently waste 10-20 W of idle draw. Enable deeper package C-states in BIOS, then verify on Linux with powertop. Zero cost, often the highest impact-per-minute change you can make.

3. Spin down idle hard drives

Each active 3.5-inch HDD draws 4-8 W. Spinning down four idle drives saves 20 W ($30/year US). The catch: chatty services (logging, indexing, SMART polling) keep drives awake, so audit what touches the array. Put logs and Docker volumes on an SSD so the big drives can actually park. More in how much it costs to run a NAS 24/7.

4. Right-size the power supply

PSUs are least efficient at very low load. A 750 W unit running a 40 W system wastes more than a right-sized 300-450 W unit. The savings are real but modest — usually a few watts — so only bother if your PSU is badly oversized. Don’t buy an exotic Titanium unit expecting miracles on a low-power box.

5. Kill idle GPU draw

A discrete GPU left in a host can idle at 15-25 W doing nothing — that’s an RTX 3060 costing ~$22-37/year just to sit there. If you only need it occasionally, pass it through to a VM you start on demand, or power-limit/undervolt it. If it’s purely for transcoding, a low-power Tesla P4 (9 W idle, 75 W cap) is far more efficient.

6. Schedule non-critical machines

Not everything needs 24/7 uptime. A lab node used only in the evenings can be put to sleep with Wake-on-LAN, or scheduled on/off. Running 8 hours a day instead of 24 cuts energy use by two-thirds. Keep your NAS, DNS and monitoring up; schedule the rest.

7. Measure before and after

You can’t optimize what you can’t see. A plug-in meter or smart plug ($20-30) shows real draw, and logging a smart plug into Home Assistant turns it into a before/after dashboard. Measure accumulated kWh over a week for the true average — see measuring your homelab’s real power draw. Then plug your numbers into the calculator.

Savings at a glance

Estimates at $0.17/kWh, 24/7. Your figures scale with your kWh price.

The bottom line

You don’t need to dismantle your lab to cut the bill — you need to remove idle watts from the gear you keep on. Consolidation alone often pays for itself within a year. For the deeper engineering version of this list, see our reduce power consumption guide, and run your own savings in the cost calculator.