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Running Your Electric Meter Backwards
kog777 writes to note a story in International Business Times about "net metering," or generating your own power without disconnecting from the grid. Forty states have laws allowing individuals to do this, and many of them offer subsidies and tax breaks for people who do. From the article: "When the sun shines bright on their home in New York's Hudson Valley, John and Anna Bagnall live out a homeowner's fantasy. Their electricity meter runs backward. Solar panels on their barn roof can often provide enough for all their electricity needs. Sometimes — and this is the best part — their solar setup actually pushes power back into the system."
I live in Southern California, and one side of my roof faces south, so I should be a prime candidate for this. However, I have some concerns about actually doing it. For one thing, when we bought the house, 10 years ago, the sellers were just in the process of replacing the roof, and while they were at it, they removed the solar water heater for the pool. If you figure we have 15 years left on this roof, I have to wonder whether an expensive photovoltaic system will end up going the same way as the solar water heater. Another question in my mind is the uncertainties related to the craziness California has been seeing in electric rates, as well as uncertainties about when is the right time to buy photovoltaics, given that the technology is advancing rapidly. And then there are all the other things that might be easier and more practical than installing solar panels. I replaced a bunch of incandescent bulbs with compact fluorescents last month. I've never been able to get power management to work properly on my Ubuntu box. One of the big electricity hogs in our house is the pool pump, and there's not much you can do about that; if you don't pump long enough on the pool every day, it turns green.
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The consumer is offered two choices from the utility:
A. peak rate at $0.40/kWh and off-peak at $0.20kWh
or
B. fixed rate at $0.35/kWh
Now two neighbours sign up for the two different rates, and start their own little energy trading:
Off peak, Neighbour A buys at $0.20 from utility and sells to neigbour B for $0.35. B resells to utility.
During peak hours, Neighbour A buys from B at $0.35m and sells to utility for $0.40.
With a 400A service, they can 800,000kWh a year and make a profit of $80k!
Have fun
don't cut it off www.mgmbill.org
You also need the right gear. It is expensive at the moment, but it wouldn't be if everyone was buying it.
It's not a million miles away from the cheap inverters and UPSes you can buy. One important point is this - it must have an incoming mains supply to work. If there is a power cut, it will shut down, and most aren't smart enough to just disconnect from the grid and leave you on standby power. Why? Well, because it needs a phase reference for the incoming mains, and if the power goes down it has no way of knowing what phase it's going to be when it comes back. Imagine if your inverter is pushing out the full -120v when the incoming mains comes back at +120...
It would be possible to build an inverter that would disconnect the incoming mains supply in the event of a power failure, and "slip" the inverter until it's in phase before dropping it back in, but you'd need something like a 100A contactor for that to work.
What is to prevent people from storing electricity (in batteries) during off peak hours and then selling it back during peak hours and generating a profit?
"I'll just chip in a bit for RedHat: I actually have that installed on my university machine." - Linus, '95
This is far from an impracticable technology. In the days of wooden ships, the Dutch used to buy English ships that had become waterlogged (yes, they do...) fit them with windmill pumps and continue to use them, just letting the wind keep the bilge dry.
To be really clever, if you manage to set up a windmill pumping system, run it in parallel to the electric pump with a simple rotation sensor (two microswitches and a simple cam on the shaft, linked to a timer circuit) so that when the wind stops, the electric pump starts.
Pining for the fjords
I'm surprised the US hasn't been doing this before, I think we've been able to do this for years in the UK and it's a pretty obvious development really.
;-)
I'm not sure how well Solar Power works here though
My dad had a friend a while back that did this, I think maybe in Oregon or Washington, but I don't recall. He had a large property with a decent sized stream running through it, and set up a water wheel. It generated A LOT more power than he used, so he was constantly pumping power back into the grid, which his electric company paid him for, at something like one fifth of what he would pay for the electricity if he was drawing it. The startup cost wasn't that high, as he was an electrician and set it most of it up himself, and was way more cost effective than solar panels at the time (I don't know if that is still true, this was 10 or 15 years ago). He wasn't just saving money, but actually turning a profit of a couple thousand dollars a year.
I think some time later the regulations might have changed and the power company would no longer pay him, but at least he still had electricity that was essentially free.
Every time an article like this comes up, people are nice enough to point out problems with solar (gunk to create, $$ to invest, wears out). Still, I have to say the idea continues to be exciting
The appeal comes with the similarities to computer evolution and balance (mainframe/personal) and the internet (grid computing). People can keep telling me it isn't worth it or will never happen (or will be super-inneficient), but I'm always going to hold out for that internet-like energy grid. All your Googles and p2ps working together...figure out a way to sell ads over power and maybe you'll get free power from Google itself. Hmmm...maybe I should patent ads over power lines before it is too late.
And here is the reason you pay so much in taxes, folks. Those grants come from somewhere. Whether or not you like green power, if you live near this guy or in this guy's state (or worse, if it was a federal grant), you're paying for it. Out of your pocket. Today. If it was a federal grant, that money is debt money -- it could take a generation to pay off his grant, federally.
Government has no right to steal from me, or you, to pay for this guy's pipe dream. If he really wanted to do it, he should have done it with his own dollars, not robbing the tax payer of anything.
Of course the average greenie socialist here would mod me down, but I speak the truth -- there is no such thing as a free lunch, and this guy will get one after only 8 years or so. On your back.
Connecting these devices can create all kind of havoc in a high voltage electrical grid. It wouldn't surprise me if one of these solar panels or windmills will cause an enormous blackout in the near future.
Is it worth lobbying for a industrial AC/DC rectifier in each house at the meter.
.2 volts in 40 feet.
.2 volts drop. Don't forget the current in a 40 foot length travels both ways on 2 conductors, so figure it for 80 feet.
No. Do the math. From the post it looks like you are advocating a 12 volt system for the house. Right now a 20 amp breaker feeds a 12 AWG wire just fine and you can plug in a 1500 watt hair dryer in the bathroom which is maybe 40 feet from the meter. At full load, the voltage at the outlet may drop a couple volts so you are talking 12 amps current at 2 volts in the wire or 24 watts lost in the entire length of wire.
Now the 12 volt version. From 120 volt to 12 volt at the same wattage (Volts * Amps for a resistive load) you will now need to draw 120 amps instead of 12 for the blow dryer for the same 1500 watts. If you were dumb enough to try using the same 12 AWG wire the 2 volt drop is now 20 volts. OOPS.. We seem to be short 8 volts in the negative direction to get 120 Amps to the bathroom outlet at zero volts. Lets see if it were possible the 20 volt drop in the wire at 120 amps would be 2400 watts of heat in the 40 feet of wire. Can you say HOT!. Maybe we need a larger wire size. Maybe a size big enough to handle the original voltage drop of a couple volts. Our original setup at 120 volts has less than 2% voltage drop. At 12 Volts we now have a little under 20% voltage drop. Hmm we need to go to even bigger wire to reduce the voltage drop to less than
You do the math. Find a copper wire table and find out what AWG wire is required to handle 120 Amps with only
When you are done with the math you will understand why we use 120 volts and some countries use 240 volts. You may get electricuted in an accident, but you don't need welding cable for your hair dryer.
My 1KW inverter in my car uses Welding cable for leads and the length is kept to under 3 feet total to keep the voltage drop within limits.
The truth shall set you free!
The problem is that you would be getting paid retail value for the power you are selling to the company. Looking from their point of view, you should actually have two meters, one to meter the power you buy from them at retail price, and another to meter the power you sell to them, at whatever price they buy power. Otherwise, if everyone started generating their own power part of the time, the power company would go bankrupt.
Me neither.
In fact, when I read the title I thought the story was about some kind of hacking box. I do not remember what "color" is it but I do remember once reading some schematics for a box that modified the phase (or something similar) of the AC in your house when you plugged it and made your meter (only if it was analog of course) go backwards. The only thing I remember about the diagram is that it required a HUGE capacitor.
Ubuntu is an African word meaning 'I can't configure Debian'
I've looked at the cost of photovoltaics, and the ROI, and my conclusion was that I'd rather go with a wind turbine. The same thing applies - in areas that allow it, your excess power runs your meter backwards and the power company pays you for it. A pretty good selection of small scale wind turbines can be seen here. Of course, if you have 5 acres like I do, you can dream about these little darlings that start at 1.5MW power generation and move up from there. No serious zoning issues if you are out in a rural area, and your ROI is as low as 3-4 years - assuming no unusually high maintenance costs and that the power company will pay you a decent rate per kWh not some pittance.
If a typical Nuclear power plant costs a billion dollars, what would happen if instead the money was spend on solar panels for individual homes, in the form of tax breaks and rebates for homeowners that put them up? Remember, economies of scale and distribution of the grid and all those other benefits too. Seems like a no-brainer to me...
Reality has a liberal bias
Being able to store your power onsite first-before it gets to the net metering phase, is a huge benefit and one of the primary good reasons to have onsite power production. We've seen just a ton of news stories over the past few years of whole regions going down from storms, etc. Heck, there are still a lot of folks in the midwest struggling with that now. Think of it as a whole house (or however many circuits you have activated, you can pick and choose) UPS system then it makes more sense. And that's the good part of home solar, you can do both. From my experience, on a good sunny day by around 1:30 PM or so your battery bank should be pretty full if you have sized your system properly, then it's gravy after that, all afternoon. You are still sitting on enough juice to run everything for at least a full day, and your meter can be running backwards then if that is the set up you have.
Most electric companies now install unidirectional meters to prevent this. When I had my solar system installed, the electric company had to come out and replace my unidirectional meter with a bidirectional meter so it could spin backwards and credit me with the excess power I was feeding into the grid during the day.