Lately, I’ve been working on running some of my mining gear off solar. I’ve got a couple of Mac Minis pulling full-time Monero mining duty, and I’ve been trying to get my Mini DOGE and Mini DOGE III ASIC miners back on solar power too. I don't want to be paying for the power if I can produce it!
I set up a 12-volt system with around 900 watts of panels and a 60-amp MPPT charge controller. Everything looked solid on paper. I had setup many small 12V solar system in the past when I lived the van-life, but once I had it all hooked up, something wasn’t right. I expected to see a lot more power coming into the charge controller. Instead, I was seeing way less wattage than I should have. On top of that, my battery bank wasn’t recovering after the ASICs ran during the day. It was draining and staying drained.
Tracking Down the Problem
At first, I figured it might be a panel issue or maybe some weird shading problem. But everything looked good. The sun was out, the panels were clean, and the charge controller seemed to be working. So I started looking at my wiring. I had used 8 gauge pure copper wire, which I thought was more than enough. It wasn’t some cheap copper-clad aluminum either. This was the good stuff.
The problem wasn’t the quality of the wire. It was the size of it. At 12 volts, to pull 900 watts, you're pushing about 75 amps. That’s a lot of current to move through 30 feet of wire. Even with good copper, 8 gauge just isn’t thick enough for that amount of current over that kind of distance. The result was a big voltage drop between the panels and the charge controller. That lost power was turning into heat and just disappearing before it could charge the batteries.
Voltage Drop is No Joke
I underestimated how much of a problem voltage drop could be. I thought as long as the wire was good quality and not crazy long, I’d be fine. But as I am learning, when you’re dealing with low-voltage systems like 12 volts, every foot of wire counts. The lower the voltage, the higher the amps, and the more important it is to use thick enough wire. Once I upgraded to 2 gauge copper wire, the system started acting like it should have from the beginning. The charge controller began pulling way more power, and the batteries actually had a chance to catch up during the day.
Plan and Get the Right Gear
If there’s one takeaway from this whole thing, it’s this: don’t skimp on your system and get the right gear upfront. Even if you’re using pure copper, if the wire isn’t thick enough for the job, you’re going to lose a ton of power and wonder why your system isn’t performing. I tried to save some bucks and ended up losing what I saved in time and power efficiency. Not worth it in my dudely opinion. What I should have done in the first place was to plan a 48V system, but all I knew was 12V, so that's what I went with.
I bought everything in 3's and could go 36V, BUT, the problem is my other components are not compatible with 36V, only 12V, 24, and 48V. So I am pretty much stuck with what I have at this point. The 4th battery and panel was going to cost about $500 more, and instead, I bought a mining computer. In hindsight, not the best move...
Next Time, I'm Doing It Right
I’m already planning my next solar expansion and this time I’m going 48 volts. Higher voltage means lower current, which means you can use smaller wire with less voltage drop. Turns out my 8 gauge copper wire will actually be perfect for that setup. If I can find a safe way to connect my current panels to some bigger wire, I may upgrade to some 0 gauge, but that's gonna cost a pretty penny to do that, but would be worth it in the long run.
Until next time...
Be cool, be real, and always abide with you my dudes!