Working Off-Grid Efficiently
I&#x27;ve lived for extended periods (up to 9 months) in my self-built Sprinter, with 550W of panels on the roof, and 455aH of battery inside. That system runs the lights, the fridge, the toaster, an electric kettle, the heater fan&#x2F;pump, water pump, a 40W audio amp, and my purpose built computer.<p>The computer is a mini-ITX i7 quad core, with a &quot;micro power supply&quot; that lets me plug it (almost) directly into my batteries.<p>Things I&#x27;ve learned:<p>1) you can&#x27;t plug directly into the batteries if you&#x27;ve got a smart solar charge controller. That will sometimes take the DC circuit voltage up to levels that the micro PSU considers unsafe, and the computer will shut down. I had to add a voltage regulator to keep the DC V levels seen by the computer (and other equipment) within range. My Morningstar charge controller will lift the DC V to 14V fairly often if there is a lot of sun and the batteries are moderately discharged.<p>2) Monitors are a problem. Some years ago, you could find monitors that accepted a standard 12VDC power plug fairly easily. Then someone figured out how to shrink the monitor PSU (thanks, Apple!) and they vanished inside the monitor case. You now have to hunt really hard to find anything that is 12VDC native. This is another argument in favor of laptops.<p>3) Native (desktop) software development is a totally different ballgame than webdev for this scenario. As I mention a lot here on HN, compiling my software is a major issue no matter whether I&#x27;m grid connected or not. It takes time, and it takes power. It actually takes <i>more power than the refridgerator</i>. If you&#x27;re going to just &quot;be online&quot; all day, or just working in the cloud, or just pushing data to and from the cloud, you don&#x27;t need much power (my setup would last for 4-5 days of that kind of work. But if you&#x27;re going to be compiling code (i.e. 100% CPU utilization) for extended periods, you need a lot of power. That means panels and&#x2F;or batteries.<p>4) Laptops offer more power flexibility in part because they have their own batteries. You can get them fully charged during peak insolation, which doesn&#x27;t take long, and then allow the remaining sun to keep charging your main batteries. Sometimes you can get another charge into the laptop batteries before sundown, giving you another nice blob of energy to use in the dark. You can also use them outside the vehicle, which for some people is important (it isn&#x27;t for me, in general)<p>5) I experimented in the beginning with a wifi antenna on an extensible mast. It connected to an internal router (also directly powered by 12VDC from the batteries&#x2F;voltage regular). I gave all that up fairly quickly. Open wifi worth using is vanishing rare (thanks, telecoms). I ended up with a Verizon jetpack (grandfathered into an unlimited 4G data plan for US$70&#x2F;month) and use that exclusively. It has been really great, generally even better than trying to use the wifi when we stay at friends&#x2F;family.<p>6) in the not too distant future, I will switch out my aging AGM (lead-acid, but better) batteries for lithium ion, which will effectively double the size of our battery store (Li batteries can be fully discharged)<p>7) smart charge controllers are great for battery life but terrible for power collection. They will (correctly) limit the current to the batteries based on their current charge level, tapering off as the batteries near full. This can lead to situations where there is full sun available all day, but it still takes hours to get back to 100% because the charge controller is being careful and looking after your batteries. This is good for longevity of lead-acid batteries, but infuriating if you need to &quot;bank&quot; the power as fast as possible (e.g. its going to be cloudy this afternoon). This issue, IIUC, goes away with Li batteries, which are happy to accept about as much current as you can give them (they just need to be above freezing).