For years, Bitcoin mining’s biggest PR problem has been its energy footprint. Every few months, a new study compares the network’s electricity consumption to a small country, and critics sharpen their knives. But a new open-source project is flipping that script, turning the surplus energy from rooftop solar panels into a Bitcoin mining operation that never touches the grid.

Project Solar Mining, launched on March 1, 2026, by developer MalachiRevolts, is a software tool built for the Home Assistant ecosystem. It automates the process of running small-scale Bitcoin miners using only the excess solar energy a household generates, the power that would otherwise be sold back to the grid at whatever rate the utility company feels generous enough to offer.

How it actually works

The software plugs into Home Assistant, the popular open-source home automation platform, requiring version 2026.2.1 or later. It monitors a household’s solar production and energy consumption in real time, then decides whether there’s enough surplus power to fire up a Bitcoin miner.

Specifically, it can control up to three NerdQAxe++ miners through Zigbee smart plugs. These are low-power mining devices, not the industrial-grade ASIC rigs that fill warehouse-sized facilities.

The clever bit is the hysteresis mechanism. Miners only activate after 15 consecutive minutes of available excess power, and they don’t shut down until there’s been a 7-minute stretch where the surplus disappears. This prevents the kind of rapid cycling that wears out hardware and drives up maintenance costs.

Compatible miners need to be running firmware version 1.0.36 or later, and the entire codebase is available on GitHub for anyone who wants to inspect, modify, or improve it.

Why this matters beyond the tech

The residential solar market has a growing problem. As more panels go up on more rooftops, grid operators in some regions are cutting net metering rates. In parts of California, for example, solar export rates have been slashed dramatically under newer tariff structures. Homeowners who invested in solar expecting favorable buyback rates are finding the economics shifting under their feet.

There are no corporate backers behind this initiative, no venture capital announcements, and no token launch attached to it. It’s an open-source community project, shared through the Home Assistant forums.

What this means for investors

A miner running on free solar electricity has zero marginal energy cost, which means it remains profitable at much lower Bitcoin prices than grid-powered operations. But the hardware still costs money, and the returns from low-power residential miners are modest by any measure.

The Home Assistant ecosystem has millions of users worldwide, many of whom already have solar monitoring integrated into their setups. The jump from monitoring solar production to monetizing excess energy through mining is a relatively small one, especially when the software is free and open-source.