Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?

Comment Re:Floor heating (Score 1) 557

Along the discussion of the DC home, a good inverter and maybe dedicated DC outlets. Maybe just feed outlets directly from solar/wind battery bank.

I'd add switchable glass windows to go "opaque" whenever I wanted, at least in the bedrooms.

Running low voltage DC over long distances properly is difficult, as you need bigger wiring, switches, fuses, etc. I'm not sure I'd want to do a lot of home wiring with it. Modern inverters are relatively efficient and fairly reliable. I would say that the way to go would be to pick out a few circuits for 'critical' loads you would like to be able to supply backup power to or run off grid, and run them into a separate sub panel. You could either just wire this into your main panel during construction, or install a battery/inverter system right away that would act like a big UPS to the loads on the sub panel. You can get inverters that will work with batteries, but push excess power from solar/wind into the grid while the grid is up. If it goes down, you can run your critical loads on battery power.

For some low voltage things I'd maybe consider a separate, smaller PV system and locate it close to the load, maybe for something like garden lights or ham radio gear.

Higher voltage DC is an interesting idea, especially since you could probably run a lot of switching supplies off of it - some data centers do this. However you need special switches and fuses to be able to interrupt it. I'm not sure 120/240 VDC is something I'd want in my home.

Comment Re:Help me out here a little... (Score 1) 533

So let's suppose we charge everyone a connect fee for grid maintenance. That covers the cost of maintaining transmission systems, LV networks and excess unused capacity. It will also raise the cost of utilities for the poorest fraction of society. I was shocked to learn that there is a large segment of utility customers who use very little electricity. A connect fee would, for many of them, be a significant price increase.

Solar aside, people aren't really just paying for their usage. As you pointed out, part of the bill goes toward maintaining infrastructure. To the end user, this doesn't just mean that their usage is covered, it means that their usage pattern is covered as well. Some customers may not use much energy, but they may want to start a large load once in a while.

For instance, I don't use a lot of power, but suppose I came home and found three feet of water in my basement, so I go out and rent a couple of big submersible pumps. I run these for a couple hours, and my instantaneous power usage is around 4 kW during that time. Even if this is still a relatively small part of my bill (it would be about $1), it's still a lot more power than I normally use, and the grid has to be able to support that, and ideally it would be able to support that whenever I needed it.

Now, I think that the connection fee could be adjusted depending on the particular installation (eg, residential vs industrial, city vs country, etc), but I don't think it's necessarily unreasonable in and of itself.

Comment Re:Batteries are too expensive (Score 1) 533

I ran the numbers a while back regarding the electric usage in my apartment along with the connection fee. (That means that the less energy I use, the more my cost per kWh effectively goes up since more of my bill is the connection fee.) I found that, for my usage (90 kWh/month), I could almost put together an off-grid system that would effectively cost me the same or less. That assumed I'd do the installation myself, of course, and it's not really something I plan to do. But it was interesting.

There definitely are times when the off-grid route would be cheaper. If you had some remote land you wanted to put a small cabin on (or maybe just some kind of radio repeater or something), depending on your usage it could very well be the better deal to go off-grid. On the other hand, for a normal suburban home I agree with you, batteries need to come down. Used electric car batteries could make things interesting, though.

Comment Re: TOR (Score 1) 145

That's why it's a good idea to encrypt data over Tor whenever possible - it's really only there to anonymize. If you're careful and stick to SSL-capable sites for things like email and banking, you should be fine. Otherwise, yes, assume someone will sniff your password.

Comment Re:Who pays for the infrastructure costs? (Score 1) 516

This is not simply hooking you into the grid. This is also putting in equipment to allow you to push power BACK to the grid. That's neither inexpensive, nor trivial.

What equipment on the grid are you referring to here, aside from maybe meters that are asble to sense power moving in either direction?

Comment Re:Solar power terminology (Score 1) 516

Many people do not realize that solar installs will go dark during a blackout with out these very large and uber expensive battery systems.

In most cases this is true, the invereters designed to work in pure grid-tied systems won't supply power without a battery. SMA however has an inverter that can supply some power (up to 1500 watts) during a grid outage, while the sun is up. Obviously it doesn't work at night, but in the event of some kind of disaster at the very least you can charge cell phones, laptops, or whatever when there's sun. Hopefully this is something that starts showing up in other inverters.

On the other hand, if you have something that would require a UPS anyways, a hybrid inverter and battery might just be the way to go.

Comment Re:Unlimited = No Sharing (Score 1) 209

Anyone have experience with non-root tether apps on Android?

If you don't mind getting your hands a little dirty with adb and OpenVPN, you can take a look at azilink. It basically runs a Java-based NAT on your phone, which communicates with OpenVPN on your computer. I had some issues with the app on the phone crashing once in a while, but for the most part it works. It might work better for you.

Comment Re:historical context of licensing in america (Score 1) 371

Out of curiosity, what are your feelings with encryption regarding HSMM-MESH? I mean in terms of controlling other nodes - if I have a router set up in a remote location, I want to be sure that no one else can take control of it unless I allow them. This is especially an issue as the hardware is fairly ubiquitous and well-known outside the ham community, so I would be concerned with security regarding outsiders.

The proposal mentions encryption in the case of controlling an unattended station. I don't think this is a bad idea (so, in the case of HSMM-MESH you could use SSH or HTTPS to manage a node), although I do understand the general objection toward encrypting general traffic. I suppose too that as long as the node could verify your identity you wouldn't need to necessarily encrypt, as long as it was done so that no one could tamper with the signal.

Comment Re:What a sham (Score 1) 115

The other thing is that it's not like one person would have to tie a charging slot up for two hours while their phone charged. If people with dead phones plugged in for a few minutes a lot of them could get just enough of a boost in for a quick phone call or some text messaging. It's not a lot, but for a lot of people it could be great for getting a word out to friends and family. It doesn't have to fully charge everyone's phone to be effective.

Comment Re:Disaster to the Station (Score 1) 115

This really depends on how they're built, and where they're sited. If they pay attention to those details there's a good chance that something that would take out the power would leave the kiosks usable. Strengthening the infrastructure is good and should also be done, but then it's still a major point of failure. At leas this is some additional redundancy.

Comment Re:Philosophically, like ham radio ... (Score 2) 45

There's actually an amateur radio project to create a mesh network, as WiFi channels 1-6 actually fall into the ham bands. It's not very widespread in that you can just set up a node and get on, but it is pretty easy to deploy at events or in emergencies - just take the router out and plug it in. The site is

Comment Re:Hopefully it fixed a lot of bugs .... (Score 1) 95

A lot of the visual effects companies tend to run Linux on workstations (except for things like Photoshop, obviously), as well as on the servers. Not sure what Pixar's using on their workstations, but either way 3D modeling and compositing are different beasts than editing.

That said, there are a few commercial video editors that seem to support Linux; I found out about Mistika on Wikipedia. I'm not sure how widely systems like that are used, though.

"Anyone attempting to generate random numbers by deterministic means is, of course, living in a state of sin." -- John Von Neumann