Several components of my home network run off of low voltage DC, 12 or 24 volts. The computer I'm using as my router is one example – it's a fanless industrial PC that actually takes I think 10-32 VDC. I have it running from a 24 VDC power supply.
My small off-grid #solar power system gets used for things like charging batteries and occasionally running my laptop. I make an effort to use it, and not just let the battery float, but I've been thinking about how to divert some of the excess power.
One idea I had was to use a small DC-DC converter, going from 12 VDC (from the battery) up to 24 VDC, diode OR'd with the power supply running my router. It would basically look at the input voltage, and push current up to the 24 VDC side such that the battery didn't sink below 14 VDC (or some other setpoint). The idea being that when the battery is in absorb, you can skim excess power off the top.
This is interesting because another option would be a grid-tie inverter. In my case, I'd need to find a small one that could officially work off of a battery. There are plenty of cheap ones available, but I'm not sure they're approved for this application, and I'm not sure how much I trust them in general.
The converter should be relatively safe if done right, and doesn't interface directly with the grid. The computer I'm thinking of draws 20-30 watts continuous, and while it won't consume all my excess power it can take some and do something somewhat useful – I will admit that a lot of the time it just idles.
It's sunny out. I am running my laptop. If you have a #solar electric system, the only real way to waste solar power is not to use it.
When it gets sunnier I have quite a bit of power available through this. I'm on grid, and this is kind of a hobby/backup source, but I try to skim excess off the top when I can.
But I also try to keep my battery charged most of the time, especially if it's close t inclement weather (which it isn't right now). I haven't made the jump to lithium iron phosphate for this system yet, so keeping it charged is beneficial since it's lead acid.
A future project will provide an easier way to top it off from the grid, as well as making transitioning between grid and solar AC power easier. But that's for future posting.
My home networking gear is sitting on a UPS right now. My power is reliable, but every now and then it goes down for an hour or so. It's rare, but it happens. To solve this, I took an old UPS and added a couple bigger batteries, which sit on the shelf next to it. This provides 18 Ah at 24 VDC, which is 2-3 times the capacity of the original batteries. My total load is a hundred watts or so.
This has worked well. I would, however, like to make some changes. I have some smaller network devices, a switch and Raspberry Pi in particular, which could run just off of 12 VDC. I have toyed with the idea of powering these directly from a battery floated across a power supply, or with some kind of DC UPS or switching arrangement. It would also allow the possibility of adding #solar power into the mix, adding it in parallel.
This is a low priority, as things are working now. But something to think about for the future.