Mining BTC with excess solar: My journey from running to the basement every morning to building a fully automated, dynamic mining software

Last year, we finally had a solar (PV) system installed on our roof here in Germany. Like anyone who gets a solar setup, the first thing you do is obsessively calculate how long it will take to reach a 100% ROI.

Here in Germany, the feed-in tariff is pretty bad – we only get about 7 cents per kWh we send back to the grid. That’s almost nothing. So, we came up with an idea: what if we used our excess solar energy to mine Bitcoin instead of giving it away for pennies?

We bought an ASIC miner, installed Braiins OS, and got it running. But we immediately ran into our first severe problem: Manual Management.

Every single morning when the sun came up, one of us had to run down into the basement to turn the miner on. In the evening, we had to run down and turn it off. Sometimes we missed the right timing, and the miner ended up draining our expensive home battery, or worse, pulling power from the grid (which costs around 30 cents/kWh here).

It didn't take long for us to realize that this wasn't sustainable. We needed an automated solution. I started researching and found that people use Home Assistant, but it requires a lot of tinkering and DIY scripting. I wanted a ready-made, plug-and-play solution purpose-built for solar mining.

Since I couldn't find a software that fit my needs, I started coding my own. I built a program that reads data directly from our home's smart meter and communicates with the miner's API to dynamically adjust the mining power.

But this introduced a whole new set of challenges. The biggest one: The "Passing Cloud" Problem.

What happens if the miner is happily hashing away at 3,000 watts, and suddenly a thick cloud blocks the sun? Your solar surplus instantly drops from 12kW to maybe 2kW. If your miner doesn't react instantly, you are suddenly buying expensive grid electricity to mine Bitcoin, which completely ruins your profitability.

How I solved it: I engineered the software to constantly monitor the smart meter in real-time. The moment the solar surplus drops, the software instantly sends a command to Braiins OS to downclock the miner and reduce the wattage. When the cloud passes and the sun is back, it ramps the hashrate right back up. It continuously "surfs" the solar curve perfectly. No battery drain, no expensive grid draw – just pure, 100% green surplus mining.

It worked so incredibly well for my own setup that I decided to polish it into a real, user-friendly application: SolarMiner.app.

Today, I want to share this software with the community. You can download and use it for free on your homelab server to automate your own solar mining setups.

Because I’ve poured countless nights and weekends into developing, refining, and fixing bugs, the software has a small 2.5% dev fee (mining fee) built-in. I thought long and hard about how to monetize this fairly, and I believe this is a win-win:

Paying a 2.5% fee to ensure your miner runs 100% automatically and never accidentally buys expensive grid power easily pays for itself. Without automation, you either lose money on grid power, drain your home battery, or leave the miner turned off entirely when you aren't home to monitor the sun. 97.5% of perfectly optimized, dynamic mining is infinitely better than the alternative.

I’d love for you guys to try it out, tear it apart, and give me some feedback. Happy to answer any questions about my setup, the code, or solar mining in general!

Cheers!