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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."
With a Ferarri when you stick it in reverse.
Task Mangler
Back in 2003 I decided the time was right to go green. At the time I was paying about $2900 a year for 15,500 KwH, and I figured I could make the money back in a reasonable number of years. After many discussions with local solar installers I picked one and in December 2003 I had 48 panels, each 60 inches by 30 inches, installed on my roof and three inverters on the side of the house to convert the DC output to standard household AC.
The panels generate approximately 7.5kW AC (8.8kW DC). The total cost was $65,000 but with a grant from the State of California and State tax credits, the total cost was reduced to just over $31,000. Since then I have been paying only the minimum price for electricity service (around $5 a month) to cover the cost of the meter rental. As electricity rates have increased a bit (and no doubt will continue to increase) I calculate that I will recover my costs approximately 8 years after installation, and I will then start to save money. The life of the panels should be around 30 to 40 years
It's worth remembering that you need to make certain your roof is good for the years the panels will be operating, so for some it will also mean installing a new roof first. That wasn't an issue for me as I have an ornamental metal tile roof that should last much longer than the panels.
Essentially, I use the power utility as my batteries - during sunny days I generate much more electricity than I use and the excess goes into the grid, and then I use power from the grid on rainy winter days and during nighttime. I get credited for electricity sent to the grid, and yes, the meter really does run backwards.
One neat trick is that I don't have to generate the equivalent of all the energy I use to break even. I'm on a utility company plan where the electricity I use during peak summer times (noon to 6pm) is very expensive - around three times normal rates - but off-peak usage is about 70% of normal rates. But I get credited at the rate in place at the time of day the electricity is generated. Because my installation generates the majority of the electricity during the peak times, I get credited for those KwH at the high rate and when I need to use electricity at night I pay the reduced rate. As an example of how effective this is, last year I generated 12,400 KwH and I also used 3,600 KwH from the utility company. But at the end of the year I had a credit balance of $380.
There's one gotcha there - if you have a debit balance at the end of the year, you have to pay it. But if you have a credit balance, that gets lost. Ideally you want to generate just enough electricity so that your adjusted balance is zero, but that's pretty hard to judge. In any case, you want ample extra capacity just after installation as the panels reduce their efficiency by about 0.5% to 1.0% per year.
This is however only true on average. If, for example, you live in an area where you get tax-breaks or subsidies for installing, then this can be enough to break even. In Germany, for example they have a "100.000 roofs" program where you're guaranteed a price about 3 times market-price for the power you produce for the next 15 years. That is *more* than enough to make it profitable.
Solar water-heaters on the other hand are beneficial. Especially if you live in an area with plenty of sun *and* have a large family that likes to frequently shower in the summer, it can be a huge win. There are substantial savings from installing them at the same time one installs roofing, so your best bet is probably going to be to install them at the same time your roofing needs replacement anyway, rather than separately.
The *most* beneficial investment however is building/buying a well-insulated house with balanced ventilation. This saves power in summer for AC, and in winther for heating. And a well-insulated house doesn't have higher maintenance-costs than a poorly insulated one.
Back in the 'good old days' you could hack the meter and switch the wires around so that the meter would run backwards, even though you'd still be getting electricity. A one-time friend of the family did this in a shop he owned. He figured he'd switch it, operate for a week on, week off, so the bill would be low, but not too low. Unfortunately he forgot about this arrangement and the meter showed him to be $1000+ in 'credit' with the electricity board saying they were going to be visiting in a week or so. Panic ensued, and he bought a bunch of electric kettles and rigged them up 24/7 to suck juice from the grid to get back into the red.
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.
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.
Actually, they drop it because grid-tie inverters are REQUIRED to disconnect from the grid when the grid goes down. This is to prevent backfeeding the disconnected island and frying a lineman who's trying to fix the downed wire for your block and thinks the lines are dead when YOU kept them live. (Those pole-pig transformers work just FINE in reverse, so a lineman might grab a line with 12,000 volts on it and a couple kilowatts to keep it that way while he's dancing and trying to breathe.)
Now the EASY way to do this is just to monitor the frequency and voltage, and shut the inverter off when it goes out of spec (meaning the grid is probably dead and the line only looks hot because of the inverter backfeeding it).
For a couple grand more, in the case of some good inverters that are designed for it (such as some of the Xantrex models), you can add a box with a relay, a phase-difference monitor, and a subsidiary "brain" board (or get an inverter with the function built in). (Actually the box in question usually also has the line monitoring circuit and combines with inverters that are otherwise stand-alone non-grid-tie.) That box will disconnect the inverter-and-keepalive-lodds from the line and let it keep going during an outage, then tell it to drift phase until it matches and hook it back up once the grid is back and has stabilized.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Although solar cells aren't cheap, the prices have come down, and efficiency has gone up over time. It's kinda like buying a computer... If you're waiting for the fastest computer to come out before you buy yours, chances are you're reading this on a TI57 programmable calculator.
If you buy now, your savings start now. If you cover the cost of the cells in saved energy bills and rebates from the power company, then the fact that a 'better' system comes out later doesn't hurt you that much.... Once you have covered the original cost, you can always replace the system with a new one, and you really don't lose anything. (but you get the satisfaction of preventing the waste of a few barrels of increasingly precious oil, and slowing global warming by just a smidgen).
Before you do something, ask yourself "what would happen if a million people did this"?
Free Software: Like love, it grows best when given away.
Want to improve your Karma? Instead of "Post Anonymously", try the "Post Humously" option.
So, what's the downside, then?
... and then they built the supercollider.
Staying at home and working is not so bad. I didn't get this from slashdot but it is an excellent resource that I use for targeting my marketing: http://www.dsireusa.org/
Click on a state, look under Rules, Regulations & Policies for net metering rules.
You can also look on my website http://www.jointhesolution.com/mdsolar so see utility rates.
Click on the map then click on a state. If you see the utility listed you can do net metering there.
I think Bill Gates has one with three digits, and it's in kilometers, not miles. The car was custom built, and they explained there wasn't room for more digits. Gates, of course, said (and who doesn't see this coming) "No problem. 640k should be enough for anybody."