Off grid power use

[mbryner]

David, welcome!   And thanks for the good data.  You are very efficient on all you electronics.   Never thought about the GFCI outlets/breakers taking up a bunch of electricity -- and we have a lot of those, too.

Bruce, it's always interesting to see what you come up with.   Are you saying you plug in the computer power supply direct to 120 V *DC*?

[BruceM]

Yes, the little FitPC2 computer 12V adapter and all the switching wall worts for various gear like USB hubs, DVD players, video extenders, IR extenders, my LCD monitor, my two HP and one Cannon inkjets all work fine on 120VDC. My Samsung P410M projector's supply works fine also.  Most modern switching power supplies will work.  

I'm using Verizon broadband for internet; it uses a tiny amount of power with a good directional antenna. I can't see the difference when it's on. It's USB powered, so it must be less than 100ma of 5Vor less than half a watt. Perfomance is variable but somewhat better than rural DSL, which is not available here. Satellite is a power hog in comparison.

I did have to replace the AC charger for my Dell laptop that I use for portable in-circuit reprogramming PIC and PICaxe microcontrollers.  It wouldn't charge at full rate on 120VDC. A cheap aftermarket unit works fine.

So it's back to future, Edison was right.  

PS- Other off grid and 120VDC living notes:
I have a 1930's vintage toaster and clothes iron that I use regularly; they were designed for AC or DC operation.  There were plenty of homes with DC power in New York well past the 30s. It's not too hard to modify a modern toaster; you just have to add solid state switching as the contacts were designed for AC.   I enjoy my useful antiques from Edison's era.

I use an IXYS p-channel , 200V Mosfet for solid state switching of the positive 120V as I have a negative ground system.  It's a sweet FET because it's rated for analog use, and can tolerate simple,  slow gate drive for small loads without smoking.  With an IR remote in the house, I can turn on the power selectively for the remote computer, projector power for the house rear projection system and  three more circuits, which I just use for two different printers.

The HP officejet 8000 pro is a good off grid alternative to a laser printer, with very large ink cartridges and separate print heads,  but it takes up to 6 minutes after power on for the first page (very fast after that). I use a Deskjet 1000 for small printouts I need in a hurry. It starts printing in about 10 seconds. The little Deskjet 1000 sips about 12 watts while printing, less than 1 while waiting. The officejet uses about double that. I use Sophia Global refills in both HP printers- I like the cost and the low odor of the Sophia Global (dye only)  inks, and hate the paint smell of the HP pigment inks.

I have to start the Lister to run my laser printer, it's a power hog and laser printers will NOT work on DC (or most non-sine inverters) as they use AC and AC switching control (SCRs, TRIACs) for the drum heaters.

There's no such thing as GFI's for 120VDC so I don't have any. Yes, I could design and build a whole house DC- GFI with a hall effect sensor on a bar type common mode choke, but it's not urgently needed, and I don't have kids.  I also skipped the AC powered smoke detectors.  Screw 'em, I've got no AC, and as all my wiring is in EMT conduit, I wasn't about to run conduit runs for detectors that didn't need it.  I'm fortunately friends with the inspector.

[David Baillie]

Hey Bruce, Wow what a great setup.  There was no way I was going to be allowed to do anything like that on all counts
1) Legally; I got my system ESA inspected but I had to walk him through all the weird stuff
2) financially; the banks would not touch a house "without electricity" as they called it.  A CO OP gave us a mortgage when we ESA'd the electrical
3) matrimonially


David

[SteveU.]

Hi Guys
Great thread you have started here MarcusB.
Some of the very best real world modern usable Offgrid living info being put up on the Net currently.
BruceM. and DavidB. your data and systems info  are amazing. 120vdc with electronic no arc switching!!

DavidB. I am sending you a PM. Please read. Us former VGW's Charcoal Group members been searching for a lost David Baillie.
A new Group has been formed by Gary Gilmore on Yahoo.
Ha! Ha! I know well about the chicken power drain. 150 watt heat lamp each and every hour late October into April to make them happy and fool their little pea brains into giving me my 8-12 rich golden yolk winter eggs a day. 48th parrel stuff. Fortunately though I only have to hand thaw their water (with wood heated hot water) for ~40 mornings each winter.

Regards
Washington State Steve Unruh

[BruceM]

Hi David,
I hear you loud and clear on the mortgage and other red tape issues. Here it's impossible to get a conventional mortgage for an off grid home, on a dirt road.  You end up getting scalped by "private" lenders. I was lucky to get a sweet HELOC loan for my former grid home (now a rental) to help finance this off grid place. This was back when they were giving away loans with a smile.  It's now 2.5 percent interest!  Since there was no bank or wife involved, I was free to do what I wanted and needed.  

I really appreciated seeing your detailed usage data. It really points out how much energy could be really saved if devices were re-designed for energy efficiency.

Those small 24hr loads sure add up to lots of AH/day.  It's shocking to see your parasite loads add up to more than my daily electrical power use, even though I use incandescent bulbs.  It's technically inexcusable, imagine the nation-wide yearly energy cost of the GFI and arc protection breakers.  So on one hand we crack down via regulation on the only lighting I can tolerate, and then via regulation add new 24/7 loads that exceed the lighting savings.  (No real savings as the heat "loss" is no loss at all since most of my lighting is in the winter months, when I need the heat.)

Just your code required beakers- 432 watt-hrs/day=157.7KWH/year  Wow, that's more power averaged over time than you need for your washing machine. (263 watt-hrs/day).

What brand of inverter do you have (that draws 30 watts)? Is that about average?

Thanks again for your thought provoking post!

[David Baillie]

Don't I know it!  It was in part a conscious decision though.  We could have designed a 12volt house and gotten away from so much on the phantoms but then you end up with a one of a kind jewel that "scares" people away.  I build so I wanted to be able to entice people in with the idea of a "normal" house.  Plus should we want to start again we can call up the electric company and boom its marketable.  That's the price you pay.  Bruce Have you thought of going over to a 12 volt chest freezer/fridge when the propane unit dies?  With the cost of panels so low now and a modern efficient electric fridge it should end up cheaper then the propane unit;only when the propane unit reaches end of life of course.

Bye for now, David

[BruceM]

When people ask, I recommend just what you did, David, an off the shelf 48V/sine wave inverter system including buying an energy efficient AC 'fridge, not the overpriced DC models. That is the standard for systems here, and with big name products, it helps resale.

The other thing I suggest is that they add a military grade power filter to the inverter output, and preferably use EMT conduit for the home wiring, and avoid inverter, battery bank, or PV panels near the house (PV and wiring also radiate the EMI from the PV charge regulator and inverter).  Presently, commercial sine wave inverters generate a lot of high frequency EMI on the AC, making it as bad or worse than the typical grid "dirty power" situation, where people with a family history of autoimmune diseases tend to fall apart, and cancers seem to be promoted. I believe the independent research that indicates this high frequency energy radiating from the wiring is a health stressor,  as my epilepsy is severely aggravated near homes with inverters on.  I don't last 15 minutes, even 50 feet away outside. I can be comfortable for a couple hours in one with heavily filtered power and EMT conduit. (Genisco filter)  Especially for families with members with health problems, I think it's a good idea to filter. It's good health insurance.

I've thought a lot about doing an electric refrigerator.  I can't use the overpriced DC units "as built" since they generate too much EMI and the audio noise is bothersome for me (thus no fans in my home).  I planned my 120V system capacity to handle a refrigerator/freezer, but my plan was to make a custom two compressor system, with the compressors 50 foot from the house in a doghouse, using a buried water tank (series of 50 gallon plastic drums)  for a heat exchanger. By using dual compressors, no fan is needed in the house "box with evaporators only".  I expected to use the small DC compressors with their brushless motors, but do my own low EMI controller. That was going to be quite a project. Doable and not "high risk", but still a big project for me.

My family was kind enough to buy me a propane refrigerator for my birthday about 4 years ago. It is very simple, works well, and makes no noise. Converting it to sealed combustion only took two days work, much of that thinking and measuring.  Defrosting is as simple as turning it all the way down overnight and emptying the jug it fills via drain pipe.  I have a hard time justifying the development cost and engineering time for the custom electric refrigerator, though when propane gets to $8 a gallon I'll surely reconsider!

Best Wishes,
Bruce

[David Baillie]

Hey Bruce,  I have thought about building myself a power room away from the house with a single conduit carrying the ac in.  The humming transformer in the basement is a concern.  We don't seem to be affected by any of the symptoms but the thought of a man cave devoted to power is appealing; as is recovering that space in the basement.  Do you have any links to the filters you recommend.  I am going only on company specs but my magnum inverter is supposed to be pretty "clean".  I'm not equipped to scope or truly measure anything like that though.  A 48V system is appealing but the 24V system is already an upgrade from our original  12 volt trace inverter system.  You build what you can and you live with it...
David

[BruceM]

The Radio Shack 12-467 or 12-586 portable AM/FM radios ($16-$18) have crappy tuners and are the best of the small portable AM radios to use as a poor man's "near field sniffer".  If you tune one between AM stations and then hold it near any AC line in your house, you'll hear the problem with  inverters. The radio has to be very close to the source to be affected, the receiver must be totally "swamped" as the source is way above the AM band.  If you can pick it up a couple feet away or more from a wire, it's very bad.  There are no low EMI inverters presently sold, because the manufacturers aren't considering that as a design issue.  When they say clean, they are talking power frequency harmonics, not the high frequency RFI/EMI.

Even on grid, you can have some nasty quality AC detectable with the AM radio. If so, step one is to just flip breakers to find the offending circuit and equipment. Arcing at old thermal fuses in doorbell transformers and such are common causes.  If the source is present with all breakers off, then it's time to go hunting the neighborhood, and the power lines.  An air band radio with a hacked off UHF antenna will allow you to locate the source to a single pole, a stock air band radio will get you to withing a few poles. Arcing caused by loose connections is the most common source, and has a characteristic 60 or 120 Hz sound you can hear on the AM or Air Band (100MHz AM) radio.

Trace had a low frequency inverter design- their SW series, that is about the best basic design topology to start with to make a low EMI sine wave inverter by design.  I'll be borrowing heavily from it for my own. The technique is was not widely used as it was patented, and required the use of 3 large, line frequency transformers. What the market wants right now is small, light, cheap units, made possible with very high frequency switching with PWM sine generation. So the best we can do right now is to add on a post filter to solve the problem the hard way.

Genisco.com sells new military grade filters, as does RFIcorp.com.  I try to find them on the surplus market or ebay.  Genisco is your best bet for new units, price wise.

Here's their selection chart:
http://genisco.com/index_files/Data_GF57915.htm

You're best off with a  three filter unit, one for each hot leg plus neutral, assuming you have 240V service. You can get away with just a two filter unit on an off grid inverter setup (You may have to put a figh frequency choke on the neutral between inverter and earth ground.)  The filters need a good high frequency grounding system to work well, which means copper flashing from the case lugs into the ground, along with some of your spare battery cable to some ground rods.

When searching on ebay, military power filter are usually effective key words. Most of the military units are rated for 240V AC or DC.  (Handy for me, I use one on the DC line to the house.)