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Archive for the ‘Sell power to utility’ Category
Monday, April 20th, 2009
I saw a catalog at NorthernTool.com, and there was a ad for a wind generator 120 volts , not DC and the ad stated “Run your meter backward”. The item number in this catalog is Model #44470. It states it also comes with an inverter built in.
Why would you need a inverter for 120 volts?
Second will this piece of equipment really work as it is in this ad?
If it does work as it is in the ad what if anything else will you need to set it up and does it come under the Federal law that the power company is required to let you use it in the system as long as they are advised of the equipment being on line?
I saw an ad for a car that can go 120 miles per hour, but that does not mean I can drive it down the Interstate at that speed if I buy it. In other words, the ad you reference may say you can turn your meter backwards, but you cannot do it legally unless you install all of the required safety dis-connects as required by your local utility, you complete their application form, and then they replace your existing electric meter with a model that records each in and out electric flow separately. Some states have other requirements like providing the utility with a copy of your homeowners liability insurance policy and having a lockable handle exterior disconnect switch for their use.
Although this company is known for their quality wind products, I don’t like having the inverter mounted 75 feet up a pole and subject to all the weather extremes. The inverter is the weak link in most of these systems and I want a system where this is at ground level and have as few electronic components as possible up on a tall tower and in the weather.
Most small wind systems generate DC power for battery charging. What they have done is mounted a DC to AC inverter inside the wind turbine to convert the DC electricity from the turbine into 120/240 VAC which can feed back into the utility grid. However, you cannot legally just plug this into the wall outlet and “turn your meter backwards”.
On another note, for those readers wanting to do something like this, please understand that the power output from any wind turbine is “wild”, in that it jumps constantly all over the place as the wind changes direction and flow rate. You cannot use a standard DC to AC inverter with a wind turbine since the voltage and current goes to such extremes every few seconds. Most inverter manufacturers make a “modified” version of their solar inverters to work with wind turbines, and most are designed for ground mounting in a protected area.
Also note that there are very few areas of the US with enough wind to make these worth the cost and the easiest way to tell is if there are already other wind turbines nearby. Those areas of the US with lots of wind year-round are usually already covered with wind turbines. Although you might be the first in your area, you may want to check a wind resource map for your state first before paying out $6000 plus.
Monday, March 23rd, 2009
Is there a UL product out there similar to a DC grid tie in inverter that would work for an AC generator?
I am aware of how the DC is converted with an inverter to AC and the phase angle is adjusted as well as the phase voltage to maintain proper alignment of electric main power. I have seen wind generators plugged directly into a breaker in the main panel as a grid tie in and initially was confused on how this was causing a dead short. However, I understand how it is possible now (there is an inverter in the wind generator head which adjusts Phase angle and Phase voltage to allow simultaneous feeding), but, haven’t been able to find anything for AC generators.
What I am looking for is something that will go between my AC generator and the main panel that will allow me to directly connect to the panel without a dead short, and allowing back feeding to the main line. Also an automatic shut off or transfer switch that would turn off the generator’s power supply from pumping electric back into the power grid when the main power goes out.
I am looking for an AC grid tie in device that will not cause a dead short.
Your thoughts would be appreciated,
I can’t imagine why anyone in the world would want to do what your are suggesting, although it is technically possible. Yes, there are special “in phase” monitors that will sync a generator with the grid, but this is only dome with very larger generators like you would find in hospitals or military bases. The main reason they do this is they are on a time of day rate and if they are approaching a peak demand period, by running their generators in sync with the grid they can save hundreds of thousands of dollars per year because these rates usually carry over the high penalty for the next 11 months. In addition, this switchgear to sync the generator with the grid costs more than your house and requires all kinds of coordination between the utility engineers and your installer. You will also be required to carry a huge liability insurance policy listing the utility as the insured in case something goes wrong and your power feeds back into a down line and kills a lineman.
Inverters for solar and wind systems have special circuits that make sure power is not fed back into the grid during a power outage, and the inverters must supply this power within a very narrow window of voltage and cycles. Most smaller generators are not that easy to maintain a constant output under varying loads.
Now that you know the legal issues involved with doing this, I will give you the simple reason why nobody in their right mind would ever do this:
If you count the cost of fuel, generator maintenance, repair parts, added oil changes, and annual service, you will be paid about 20% of what your actual costs will be, because you can never ever generate electricity cheaper than a utility. The only reason many of these solar and wind systems are doing this is either they are receiving some type of grant or tax credit, or they have been given a special feed-in tariff rate.
Many people still install solar systems as some systems also offer emergency backup, or at least do not need constant fueling or make noise like a generator. The national average cost today to generate electricity from a solar system is 35 cents/kWh. The national average for grid electricity is 9 cents per kWh. You figure it out.
Thanks for the insight and your knowledge on these subjects is amazing. Everyone at times has an idea and can’t figure out why the situation is the way it is; until they ask an experienced individual.
Thank you again. So if I wanted to have some sort of “economical” unit (and I use that term loosely), we would be best off using a UL device DC based unit (solar, wind, hydro) with an inverter monitoring the phase angle and voltage back to the main panel which would shut off when the main power goes out? If we wanted any sort of power when the main power goes out we would be using a battery system or a separate backup AC generator/transfer switch which would not back feed to the main power until main power comes back on. We would then turn off the generator and manually switch the transfer switch back to main power?
I guess I am in the same boat as most people trying to figure out what will work best for my individual circumstance. Oh, yeah I’m not a millionaire so the in phase monitoring for an AC generator would be out of the question.
I will probably be investing in a solar or wind powered DC unit with an inverter for my needs. Would you recommend any companies that you have had a positive experience working with for these devices. Probably, a 2KW-5KW max output would be what my financial situation will allow.
Jeff I can’t thank you enough,
Any inverter designed for grid tie in the US should have the automatic transfer function built in. If you select a battery based inverter, it will also include a built-in transfer switch to disconnect from the grid. Some battery based inverters include a “second” transfer switch to allow also connecting a generator and the grid, and will switch to the generator when the grid is down and the battery charge is low. If you select an inverter that does not have the second transfer switch, then you will need a generator that includes its own transfer switch panel.
Monday, January 26th, 2009
Not wanting something for nothing, I just became a subscriber to backwoods home. I found the website most helpful and your answers also. More I read, the more confusing it gets. So much info is out there.
Eventually I want to put whole house on either solar or wind power or both (gridtied). I will discuss that when I get to that point in my remodeling. But that appears to be one or two years away.
But for now, just to start small.
I would like to power my LCD tv (200 watt), vcr /dvd combo (30 watt), the surround sound amp (135 watt), two laptops (max 120 watt combined), internet radio antenna (14watt), and wireless router (10 watt) from a small solar panel and a battery backup. They add up to about 540 – 550 watts
Both laptops have built in batteries for shut down purposes, and one is on a battery backup for longer grid interrupts, along with the internet radio antenna and router. But will probably use the UPS battery as the backup for the router and internet radio antenna and leave it hooked to the grid as is for now and remove the laptop from it.
When we are home or not everything runs constantly. Tv, vcr, amp are off, but have the keep warm circuit. I would like to put a manual (for now) switch in the system, so I could manually switch these items back to grid if needed. I know I could save energy by turning everything off when not in use with a power strip, but for now that’s not my point in this matter.
I live in Rocky Mountains at about 41 /42 degree latitude.
Could you give me an idea of the size solar panel, batteries, and inverter I would need to support running these items?
Does a charge controller just interrupt the power the panel produces to the batteries so a “dump” is not needed as would be needed in a wind generator?
Would I still need the GFC between the panel and controller, and the circuit breakers between the controller and batteries?
I know sounds like a lot of work and expense for a little gain. But every little bit helps down the line. And I could move these components later on out to the work shop, when I get it built.
Nobody is home all day, and split shift at nights.
We get many questions like this and the answer is – you can do this but the cost will be out of sight. It’s just not a good return to buy a solar power system dedicated to a few specific electrical appliances when still on the grid, as the solar system’s output would be totally wasted for any time periods when solar was available but these loads were not operating. Since you lose about 15% in efficiency when charging a battery, and another 10% when converting it back to 120 VAC, its not economical to charge a battery to power a load later in the day.
If you want to reduce your electric usage, install a small grid-tie solar system that feeds back into your house electric panel where it can off-set part or all of the electric loads that are operating at the same time.
If you want a battery backup system, add a battery bank to the grid tie system. Once the battery is charged, all of the solar power is sold back to the grid and the battery stays full until the next power outage. This way you will not have these charge/discharge losses during normal utility power.
Friday, January 2nd, 2009
I have enjoyed Jeff Yago’s articles. His most recent, “Solar Wind and Energy Credits” got me to wondering about the state of deregulation in the power industry.
In the 90′s I had a friend that worked for one of the local power producers in Indiana. Deregulation was supposed to open up the market for buyers and sellers.
Now I live in Tennessee, serviced by a power cooperative that buys from TVA. They have a green power program that charges the customer a higher rate so they can sleep at night, knowing their power came from a renewable source, such as wind, hydro, solar, etc. I have had no trouble sleeping without this comfort.
For the homeowner producing power, the cooperative credits the customer’s account for any surplus produced by the customer at the higher “green power” rate. When the customer draws power, they are billed at the higher green power rate. There are no cash payments for an account that produces more power than it consumes. This is the electric company’s equivalent of cell phone plans, where you carry a bazillion anywhere minutes that never get used.
My question for Mr. Yago, is it possible to sell power to another company or cooperative, allowing me (if needed) to buy power from my local cooperative at the normal rate?
Many of the problems you have identified are well known to the solar industry and as they say, the times, they are a changing. What many want more than tax credits is a national feed-in tariff. All electric utilities have multiple sources of power, and they constantly change the mix of which generators are providing the “base” grid power based on time of day and demand. For example, most utilities will run their coal fired plants full out 24/7 as this reults in their lowest cost to produce power. Unfortunately, it can take several days to re-start a coal fired plant after it has been shut down, so they cannot just turn several on and off as their demand changes. To handle these temporary system peak demands, which usually happen in the late afternoon, they will usually fire up natural gas turbines which are much higher cost to operate, but can be started and stopped fairly quickly and are used for peaks lasting only a few hours. Lastly, some utilities have pumped storage or other temporary types which may only be able to provide power for a few minutes or maybe a half-hour, but these can be started instantly.
The catch to all this is the power companies want to pay back the solar homeowners for any afternoon electricity they sell back at their “base” cost to generate power which typically is in the 4 to 8 cents per kWh, at a time when their actual cost for the temporary afternoon peak load may be over 30 cents per kWh. Since the solar sell back occurs at the exact same time as the utilities are needing to generate the extra peak power at their highest cost, what we are really fighting for is for solar to be paid at this peak rate, not the average or base rate. There are some utilities in states that cannot meet demand now and these utilities are very friendly to solar as a way to avoid building costly new power plants. There are other states where the electric utilities have plenty of capacity from coal or nuclear and they could care less about solar and do not need the sell-back power.
As electric demand continues to increase nationally each year, at some point all electric utilities will finally come to the table and be glad to buy all the solar power they can get, as this “locally produced” power goes to the local community loads and is not lost traveling along thousands of miles of power lines. There are a few a few states that do allow the type of cross-state purchasing and selling of power that you are hoping for, and there are also a few states that now allow trading solar credits. This is when an electric utility is required by their state to purchase a certain amount of their electricity from renewable energy when they do not have any. There are companies called aggregators that go out to hundreds of small solar grid-tie homeowners and “sign them up”. Nothing changes between you and your local utility, but the aggregator gets to claim that he is representing your excess power. They then “bundle” these separate accounts into one large portfolio which they sell to the utility that needs to show they are being credited for so much solar power, even though this power never actually gets wired from your home to their account several states away. These guys are paying very good rates just to “claim” your excess solar power and it will depend on your state and your local utility if you can take part in this program.
If all this still sounds confusing, it is, but give the industry a few more years and we will have all this worked out. One thing you can be sure of, if some utilities are already fighting to purchase all the solar power they can get and at much higher rates then your local utility is willing to pay, you can bet the future looks very bright for all solar homeowners even if it will take longer then they were hoping.
Good luck and be patient,
Saturday, December 20th, 2008
Recently I contacted the electric utility company servicing my home inquiring about negative metering. Prior to contacting them I had discussed the possibility of erecting a windmill on my property and selling surplus energy back to my supplier with an electrician friend. He told me the rate stunk but it could be done.
The person I talked to at NIPSCO was an absolute zero. She sent me some paperwork saying that for the privilege of giving them free electricity it would only cost me about $8.00 per month. WHAT?
So I called the number on my state’s, (IND), energy website and got a recorded message saying the person I’d reached doesn’t work there anymore. WWHAT?
Finally, I did something I’ve never done in my life. I wrote my congressman. Actually his website told me to fax his office in South Bend, IN. So, I faxed Mr. Donnally my concerns about negative metering and guess what? I received specific instructions from his office on how to file an application for welfare benefits! I was asking about watts, not welfare! WWWHAT?
Jeff, can you tell me where I can get valid useful information on negative metering for my state? Thanks.
Welcome to the new world order! Its now just like Alice in Wonderland isn’t it.
OK, I will provide you some sanity and real information.
Your state of Indiana has a net metering law that is almost just like many other states. Your local utility is REQUIRED to purchase any power you can generate up to 10 kW, and your local utility is NOT allowed to charge you any fees or other charges for this privilege.
This link will take you to your state’s utility commission’s web site where this is explained in simple terms, along with a real person’s name and phone number you can contact who understands how this works and can help you fill out the forms. Many utilities just do not have the staff or time to deal with these “smaller” projects and will play dumb in hopes you just go away.
Keep in mind that before the net metering laws were passed to allow you to do this, most of these systems were just hooked up anyway and since all it would do is turn the meter backwards, as long as you do not sell back more than you use you would just end up with a smaller monthly bill. Of course this can be un-safe if you do not use the proper equipment, but the point was, if the utility did not make this easier to do legally and at no cost, everyone would just go ahead and do it anyway!
Let us know how this turns out,
Sunday, November 23rd, 2008
I just purchased an old mill here in SC and along with it are 2 very large hydro power generators that have been stored for several years. One is a 1000 KW Westinghouse and the other is a 1200 KW General Electric.
I am trying to find a market to sell these to be used instead of just scrapping them
If you have any ideas please send me some contact info.
If I had just purchased an old mill with generators this large I would be looking into putting them back into service. With electric rates getting ready to climb through the roof in the next 2 years, these would provide all of your power needs plus selling lots of excess power back to the utilities. I would not scrap these as there are many old mills across the country that have been placed back in service by private owners and I am sure they are looking for replacement equipment and parts. As long as these have been protected from the weather they should be in good condition since they are just a rotating coil of wire.
Here is a friend of mine that is involved in this field who may be able to help you: Old Mill Power Company
Wednesday, November 19th, 2008
Can I hook up a engine driven generator to the grid in a net metering arrangement? Can I do this with an AC generator head? Can I do this with a DC generator head? How would I go about it and what equipment would I need?
If your state allows net metering then you can do this, but I do not know why you would want to. By every measurement I have seen, you cannot generate electricity with a generator cheaper than what you are paying the utility for power. The only way this might work out would be if the utility has very high rates and you ran the generator on waste methane gas from a large refuse pile or other source of free gas. Still, the wear and tear on the generator and replacement cost usually still makes this not a very good economic process.
If you do try this, most utilities will NOT under any circumstances allow a direct connect between your generator and the grid. You must separate with a power inverter that has been tested and approved for grid inter-connect. Without this separation the grid power will blow out your generators windings if the grid is energized, and if you did try this during a power outage, the 240 VAC backfeed from your generator will go through the utility line transformers “backwards” and be stepped up to thousands of volts that could kill a utility worker repairing the power lines down the street.
Thanks. I understand that much. I have already been in contact with the Utility Company and New Jersey DEP. I qualify for net metering. I also have a source of free or cheap fuel that I plan to burn, so that has been thought through. My question was about availability of equipment that would allow me to use an AC generator head to grid connect. Alternatively, if I use a DC generator head, can I simply hook it up to the inverter the way I would do for an array of solar panels? Thanks, and I appreciate your time. I had tried getting answers from the inverter-companies, but got no-where.
If you connect a fuel-driven generator to back-feed the utility grid, it is not only illegal, IT WILL BLOW UP YOUR GENERATOR!
One way you can make this work is by using an inverter certified for grid-tie application and designed to operate with a DC battery bank. The inverter serves as the “translator” between the DC battery bank and the utility grid to match the grid voltage, current, and 60 cycle wave form. The battery serves as a “buffer” . One manufacturer recently introduced a grid-tie inverter that can take the straight output from a DC wind turbine without using a battery bank, but you most likely would need to have a high voltage DC head on your generator to match the DC input required for this inverter.
In the battery-based system, the generator is separately connected through a battery charger to charge the battery bank which means you can use either a DC or AC generator depending on the battery charger. If this system will be under 8 kW, you might check into the several grid-tie inverters that are available that have connection for a generator input and include a battery charger. With the proper sizing of the generator, battery charger, and inverter, the batteries should never become discharged since you are supplying battery charging into the battery bank at the same rate the inverter is taking battery power out of the batteries at the other end.
Large utility size mega-watt co-generator plants and gas fired peaking plants do connect their generators directly into the the utility grid without first charging batteries, but they use custom designed power conditioning equipment and extensive safety equipment to prevent all of the many power and safety problems that can occur. I assume you do not have several million dollars for this equipment and do not want to spend another $100,000 for the utility permit and inspection process to allow direct inter-connection.
Check these links -
Xantrex XW System
Windy Boy 6000U
Thats all you get for free!
Sunday, October 26th, 2008
Is it possible to run one of the less expensive high voltage grid tie inverters (e.g. the Sunny Boy 1200U needs 130-400 VDC input) with just a few 12 volt panels through the intermediary of a DC to DC converter (hopefully the rectified output of a cheap 12 volt inverter)?
I’d like my three 75 watt panels to do something useful when they are finished charging batteries and irrigating the garden.
The SunnyBoy and similar grid-tie inverters need a solar input well over 240 volts DC or they cannot put out 240 volts AC to grid, and normally have solar inputs above 300 volts.
Yes, it is possible to custom design and build some kind of DC to DC converter that could take the 36 volt solar array you have and convert this to 240 volts AC, but the resulting current amps would be very low and may not be enough to overcome the efficiency losses involved. Nobody I know makes anything like this and there is a good reason for that.
In real world terms, your 75 watt solar array is so small it would best be left doing what you are already doing – charging batteries and running small pumps or fountains.
Hope this helps,