My journey to mining bitcoin from electricity created by the sun began last year on a mountain in Tennessee. At the time, my family was living off grid, exploring what it was like to take a step out of the regularly scheduled societal program and into a life of greater connection to the natural world and the people around us. We were living well with the sun as our source of electricity. So well, in fact, that there were many days that our batteries were topped off well before noon, which meant that our solar panels were capable of harvesting much more energy than we needed. I’d been hearing that bitcoin miners are really good at soaking up and monetizing excess energy, so I took a look at our system’s capacity and the miner options available. I discovered that Bitmain’s S9 miner was plug and play ready for my application, and it only cost $125. It was perfect as a low risk way to learn more about home mining and an easy way to test what it was like to mine on solar. I started plugging in the miner on sunny days after the batteries had reached full charge and it worked! I was turning the extra solar capacity into hard money. I was hooked and began dreaming of ways to optimize the system. Before long, I discovered an online community of home miners who were tinkering with all sorts of interesting ways to use miners to add value to their lives. In particular, I was intrigued by the work of Dirtyshotya from 100acresranch, who builds a tuner that allows a modified S19 series miner to run on 12v dc current straight from solar panels. This increases efficiency by eliminating the AC-DC power supply miners require when running from AC power sources. I purchased a tuner box from Dirty in November and began assembling the necessary components to build a completely off-grid solar mine. This week marked the maiden voyage of the system. As with any project that pushes the boundaries of what has previously been done, the road has been bumpy and winding. What follows is my attempt to get into writing the process, challenges, and successes of this project, both as a reference for future me and as inspiration and information to anyone who is curious about mining bitcoin with solar.
Before embarking on this project, I identified the following goals:
- To invest capital in energy independence and resilience.
- To expand my experiential capital in both solar systems and bitcoin mining.
- To setup a relatively passive income stream that reduces the ROI of the solar system.
- To harvest the heat from the miner to supplement home space heating.
I don’t currently live in a home that I’m able to add a solar system to, so I had to get creative. Fortunately, I found a family member who was willing to host the system in exchange for the supplemental heat from the miner. I have designed it so we can move it when we move to property where we have more space. The system is an asset that should bear fruit for decades.
The system is composed of the following components:
- Solar panels. Due to the design, 12v panels are necessary for maximum utilization of electricity produced. Technically, higher voltage panels will work, but they will be limited to a fraction of their maximum output because the miner requires 12v supply. 12v panels are more difficult to find. I got mine on eBay. I started with 3 Kw of capacity, which is around the maximum draw of my miner. This doesn’t mean the panels will produce 3 kW. We’ll get to that in a bit.
- Miner. Currently the firmware for the tuner supports Bitmain’s S19 series miners. I went with a j Pro 100Th machine.
- Solar tuner box. This is where the magic happens, adjusting the power sent to the miner based on what’s available from the panels and batteries.
- Batteries. 400ah of 12v lithium.
- Racking. I spent a lot of time putting together racking that was as cost effective as possible while meeting aesthetic and functional needs.
- Wiring, fuses, breakers, connectors. Due to the length of my runs, this required upsizing my wire.
Challenges in setting up the system:
- Panel placement. The roof I have access to faces east/west. This is not ideal. After careful consideration, I decided to place panels on each slope of the roof. My hope was to capture more hours of sun rather than focussing on peak power production. The jury is still out on whether this was a good idea.
- Wire run. Low voltage systems do best with short wire runs because of the expense of running wire gauges that are large enough to safely carry the amps the panels produce. The constraints of my system required wire runs of up to 45ft., which meant I had to upsize my wire gauge. This was expensive.
- Setting up the tuner box. This was mostly due to my limited technical knowledge. I was learning how to setup and operate a solar system, a bitcoin miner, and the tuner all at the same time. There’s a learning curve. I spent a couple of days foiled by a bad sd card. Slow and steady wins the race.
After running the system for a few days, some things are becoming apparent:
- The solar panels seem to be the limiting factor right now. In full sun they harvest around 750w, which is 25% of their rated maximum. My current hypothesis is that panel placement is largely to blame. The panels are flat on the roof, facing east and west. I knew this wasn’t ideal, but it seems to be even less so than I hoped. The next step is to try tilting the panels south as much as I can. Production should improve as we enter the summer months and the earth’s axis shifts to bring the sun higher in the sky, striking the panels more directly. I will need to make improvements if I expect to hash over the winter. There is enough space on current racking to add another panel or two, so that is another option for adding watts.
- Current battery capacity will only extend runtime marginally. It works well if the sun is momentarily obstructed by clouds, but if I want extended runtimes when the sun is down I’ll need to add batteries.
- Turning extra electricity into heat and BTC is fun! I see lots of potential to keep tweaking the system for maximum efficiency.
Questions? Ask away. Comments? Send’em over.