Adding Wind to a Solar GTI system

Hi:

I have the standard SUN stackable 500W GTI that everyone seems to sell connected to 400W of solar panels. I would like to add an 800W wind turbine to the system. There is very little info out there on this topic so I really need help. Here are some of the initial questions that I have:

Should I use the same manufacturer GTI for stacking?

Should I use the same wattage GTI and add (2) more of the same 500W units to cover the 800W turbine?

Should I get the same voltage turbine as my solar (24V)?

In stacking, do you just parallel the DC inputs and plug the 110 cords into the same outlet (power strip I guess would be needed). My GTI came with NO info on the stacking connections or operation.

Should I just parallel connect the DC output cables from the wind with the solar at the GTI terminals? Will they interact or fight eachother if one is producing and the other is not? Blocking diodes needed?

I assume it is a no-no to mix a 3 phase GTI with a single phase unit. The wind turbine is 3 phase but comes with a rectifier down to single phase DC. That should be ok - right?

Can I connect 2 GTIs to different locations on the same grid in my house or will they fight eachother?

Thanks - these questions have been bugging me to no end.

Comments

  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Adding Wind to a Solar GTI system

    First connecting any grid tie system with plug in inverters without permits and utility approval is illegal and is dangerous cause it can overload the circuit.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system

    This has got "bad idea" written all over it.
    In addition to what solar_dave said about the dangers of just plugging in one GTI after another to what is essentially unknown wiring in the walls:

    Wind turbines usually don't work. This is because: 1). the site doesn't actually have the kind of sustainable wind to make it viable; 2). the install isn't high and clear enough to be in non-turbulent air; 3). most of the small wind turbines are poor quality and don't perform as per manufacturers' claims.

    Wind turbines need a constant load. You might think a GTI will provide this, but not if the DC input is also being fed solar. The panels will try to put out as much current as they can, and they will supersede the turbine's output. Id est: with the input fully loaded from the PV, the turbine will have zero current demand and will spin out of control.

    The term "stacking" doesn't actually apply here, as it should be used in reference to connecting the output of inverters as with off-grid systems where inverters are "stacked" to produce more current capability or higher Voltage output. Technically you can "stack" GTI's in that manner: multiple inverters back-feeding the same utility service.

    Few inverters handle wind power well. The WindyBoy is one that does. As for using any turbine's DC output to power any GTI input ... lots of variables there that could lead to trouble.

    You are right that you can't directly couple 3 phase AC to single phase. This is irrelevant to DC connections because, as you say, the Voltage is rectified; DC has no "phase".

    To return to the original legal and safety caution, if this system did have proper approval it would need to be re-approved if the design were to be changed as in adding additional power - whether by wind, PV, larger inverter, whatever.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Adding Wind to a Solar GTI system
    dlwyatt1 wrote: »
    Hi:

    I have the standard SUN stackable 500W GTI that everyone seems to sell connected to 400W of solar panels. I would like to add an 800W wind turbine to the system. There is very little info out there on this topic so I really need help. Here are some of the initial questions that I have:

    Should I use the same manufacturer GTI for stacking?

    Should I use the same wattage GTI and add (2) more of the same 500W units to cover the 800W turbine?

    Should I get the same voltage turbine as my solar (24V)?

    In stacking, do you just parallel the DC inputs and plug the 110 cords into the same outlet (power strip I guess would be needed). My GTI came with NO info on the stacking connections or operation.

    Should I just parallel connect the DC output cables from the wind with the solar at the GTI terminals? Will they interact or fight eachother if one is producing and the other is not? Blocking diodes needed?

    I assume it is a no-no to mix a 3 phase GTI with a single phase unit. The wind turbine is 3 phase but comes with a rectifier down to single phase DC. That should be ok - right?

    Can I connect 2 GTIs to different locations on the same grid in my house or will they fight eachother?

    Thanks - these questions have been bugging me to no end.

    Apart from the other issues that have been brought up, what is it that has led you to believe that a wind generator would be a viable source of power for you? For PV systems, there are databases (ex: PVWatts) which will give a reasonably accurate projection of what a specific system will produce in a specific location. Not so for wind, and just walking out your front door and having your hair blown around is not a reliable data point upon which to base an expenditure of many thousands of dollars.

    I would recommend that you buy a small weather station and place it in the precise location where you would place a wind turbine and monitor the air movement for AT LEAST a year before spending a dime on a wind turbine, and after that to be extremely careful what you spend your money on. There are many, many Small Wind stories with very unhappy endings.
  • System2System2 Posts: 6,290 admin
    Re: Adding Wind to a Solar GTI system

    Hi - Thanks to all for the comments. There are a few surprises though.

    I have seen many videos with installs using the very same GTIs stacked. Been doing tons of research and this is the first time that I am seeing "dangerous overload" comments anywhere with solar connected to a GTI. My unit is CE registered (European certification) to do the job it was designed to do safely. It has sufficient safeguards and fault tolerance to keep me satisifed. Using the stacking function with wind is my unknown, thus the reason for seeking advise from those that have done it sucessfully or unsuccessfully.

    As far as a wind turbine, I fully understand the concept of keeping the PMA under load. There is a dump load version of the 500W GTI that will divert to a resistor bank under low demand/high wind conditions to keep it from "spinning out of control". My demand will always exceed the supply though. These GTIs are specifically designed for wind turbines. I have seen several installs with these as well. The only complaints seem to be with the Sunforce 600 which is a Chinese piece of junk IMHO.

    My wind situation is actually pretty favorable with a fairly steady breeze most of the year. The 800W unit from Missouri Wind and Solar looks like a quality PMA turbine at only $459 so I'm not worried about the cost. It is a simple unit and frankly, should outperform my solar in KW generated per year (especially because the turbine doesn't stop outputting after the sun goes down).

    Thanks again.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system

    Just to clarify the overload potential:

    If you use a dedicated line from the GTI's to the breaker box it isn't a problem: correct wire size and proper breaker and all is well.
    The trouble comes when you start plugging them in to whatever wire is in the wall. Yes, if you put 20 Amps through the line the 15 Amp breaker at the other end should trip and everything is safe. Only there can be more outlets along that line. If they have loads on them, they will "syphon off" current before it reaches the breaker. The result is that the breaker doesn't see any overload, but the first few feet of 14 AWG is seeing 20 Amps on it until it gets past the first "real" load.

    We'd be amiss here if we didn't point out the potential for such problems, as they can burn your house down. For grid-tie inverters, always use a properly-sized dedicated line straight to the main panel.
  • The Only SargeThe Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    Re: Adding Wind to a Solar GTI system

    I saw a video of a guy eating an entire LIVE chicken. Doesn't mean it is good nor would I do it.

    No question it is illegal without specific permits/inspections and your insurance company being notified and signing off. No question.

    Nobody is trying to "talk you out of" anything. They are providing you some thought food to insure your project is a success and safe. Put 45 amps down a 15 amp circuit and I wanna see your video!

    PM me if you wanna see the guy eating the chicken. It is gross.
  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Adding Wind to a Solar GTI system
    Just to clarify the overload potential:

    If you use a dedicated line from the GTI's to the breaker box it isn't a problem: correct wire size and proper breaker and all is well.
    The trouble comes when you start plugging them in to whatever wire is in the wall. Yes, if you put 20 Amps through the line the 15 Amp breaker at the other end should trip and everything is safe. Only there can be more outlets along that line. If they have loads on them, they will "syphon off" current before it reaches the breaker. The result is that the breaker doesn't see any overload, but the first few feet of 14 AWG is seeing 20 Amps on it until it gets past the first "real" load.

    We'd be amiss here if we didn't point out the potential for such problems, as they can burn your house down. For grid-tie inverters, always use a properly-sized dedicated line straight to the main panel.

    And I will add that you need to make sure all the components of that line meet or exceed the amperage specs of what your are driving to the panel. This includes the panel bus bar itself. These specs are all spelled out in the NEC. Please no plug strips.

    As others have said here, the utility has the right to know what you are doing to its grid. Once you change the line on the other side of the meter by putting watts in you are altering someone else property. If you have a fire, even if not caused by your guerrilla grid tie, you have given your insurance company an out on payment. The local permitting agencies have a right to their permitting fees and are there to protect you, your neighbors and the next consumer of your property from dangerous conditions.

    One can just imagine dropping a grid tie inverter(s) into a house built way back when using nob and tube with disastrous results. Permitting and the NEC code are there as measures for safety.

    PS have you ever seen one of their plug-in inverters UL rated, there is a reason for that BTW.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Adding Wind to a Solar GTI system
    dlwyatt1 wrote: »
    My wind situation is actually pretty favorable with a fairly steady breeze most of the year.
    Pardon my skepticism, but just feeling a breeze is not an analysis that I would spend any money on. I respectfully submit that without collecting hard data for a year or more you really have no idea what your wind potential is. Many (some might say most) folks who spend money on small wind generation are throwing their money down a rabbit hole. If you don't do your homework before shelling out the cash you are asking to be taken advantage of.

    But it's your money and you can spend it however you want. Caveat emptor.
  • System2System2 Posts: 6,290 admin
    Re: Adding Wind to a Solar GTI system

    Sarge you crack me up AND you are making me hungry!!! I'll pass on that video after I saw a news clip on the Nathans hotdog eating contest. I think the winning number was 54!

    Coot - totally agree that the branch circuit ampacity needs to be sized to handle the load. In my application, I'm looking at 400W of solar plus 800W of wind. That is only a little over 10A to the panel on a perfect wind/solar day - no problem there. The bus is sized to the rating of the panel so no issue there either. During the series of hurricanes we had here (Florida) years ago, we all had generators backfeeding into our house grid - YES with the mains off. The power company knew this and took precautions against the boneheads that didn't shut off the main breaker. Would do it again in a heartbeat. We had no power for long periods.

    GGunn - I'm not looking to install a Proven Energy 15KW turbine ( that's $25,000 on a $40,000 tower). If I was, I would run all the calcs to justify the ROI. I have an excellent book on designing mid size turbine systems that has all of the formulas. I'm talking $459 here and we do get a steady sea breaze that can actually be annoying at times. This is more for fun. When I move out West soon, I will go big time (10KW or larger) and do all the calcs - I promise.

    What I was really looking for in this forum was someone with experience stacking GTIs. DC voltage is DC voltage. Doesn't matter what the source is (assuming the trubine is rectified from 3 phase that is and properly loaded).

    Thanks all.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: Adding Wind to a Solar GTI system

    In Florida, there is NO wind technology that will have an ROI, we have no winds, literally we are in the lowest class ( 1 ) in the country

    For 45K, you can have a legal, whole house XW-6048 system with @10k of PV
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system
    In Florida, there is NO wind technology that will have an ROI, we have no winds, literally we are in the lowest class ( 1 ) in the country

    For 45K, you can have a legal, whole house XW-6048 system with @10k of PV

    Except when the hurricanes blow through and turn your expensive wind turbine install into so much shrapnel blowing through the air. :cry:

    The PV system stands a better chance of surviving that too.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Adding Wind to a Solar GTI system
    Except when the hurricanes blow through and turn your expensive wind turbine install into so much shrapnel blowing through the air. :cry:
    You've gotta be careful with those average wind speed numbers, doncha? ;^)
  • System2System2 Posts: 6,290 admin
    Re: Adding Wind to a Solar GTI system

    ******- No, there is no wind in Lakeland - LOL. However, you all should have done your research a little better. There are actually 2 areas of Florida that are a class 5 (< 8.6m/s) and where I live, it is a class 6 - YES CLASS 6!. Of course that is a mean average taken at 80M which is not very practical but only somewhat representative. Here is a detailed map from Stanford University for you to gaze at:

    http://www.stanford.edu/group/efmh/winds/global_winds.html

    Does anyone here know about stacking GTIs..... getting back to the original thread of adding wind to a GTI or am I in the wrong place? This is the GTI forum and not the "I hate wind turbines" forum....right.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system

    80 meters? 260 feet up in the air? Who is going to put a wind turbine that high up? What's the flow like down around 50 feet?

    And we don't hate wind turbines here; we're just practical about it. Too many people have wasted large amounts of $ by putting them in unsuitable locations and/or buy cheap junk turbines. Truth is, we give the same warnings about solar. It's just that there are far more locations where solar is viable than there are good wind sites.

    As for the "stacking" issue, I could have sworn I explained that already. But I answer so many questions perhaps it was to someone else. I hope that was what they asked about. :p

    The AC output from multiple GTI's can be connected to the same distribution panel providing each has a dedicated line and proper circuit protection and the total output does not exceed NEC specs for the main panel (20% over).

    The DC side doesn't care much where it gets its DC from. The only potential problems are as you already know; the need to keep the wind turbine "loaded" at all times and the probability that the PV's will do most of the work meaning the turbine will be connected to the dump load most of the time the sun is shining. If you really have got a windy site it is better to use separate inverters for wind/PV so the "argument" doesn't happen; there's no battery bank to mitigate the differences.

    I will reiterate that in my opinion this project is a bad idea, due to all the reasons mentioned before. Beyond those warnings we have no control; the responsibility and liability is yours alone.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Adding Wind to a Solar GTI system

    The AC output from multiple GTI's can be connected to the same distribution panel providing each has a dedicated line and proper circuit protection and the total output does not exceed NEC specs for the main panel (20% over).
    And if the breaker(s) you are adding puts you in between 100% and 120% of the panel busbar rating, then it/they must be at the opposite end of the bar from the main breaker.

    And if you want to install more than one backfed breaker, your AHJ may require you to add a subpanel to combine them so that there is only one backfed breaker in the main.
  • fixerfixer Registered Users Posts: 12
    Re: Adding Wind to a Solar GTI system

    Man nothing but kill joy.

    I say have fun, do it and learn. It's a hobby, let the guy have fun!

    500W... 800W... IT'S A HOBBY!!!!

    It's sad that you have to keep asking the same question over and over.

    Yes, you can stack them, there is no technical reason why not. Be reasonable with the amount of things you plug into any AC circuit on one breaker, duh.

    Good idea to use a GTI made for wind like you suggest, since normal GTI's take a while to come "up to speed" and a GTI made for wind has a dump load output.

    It may be possible with a diode arrangement to push the power into a battery while a normal GTI comes up to "speed", but then you still need a dump load to keep the battery from over charging etc... So why not use the grid as a battery? Much simpler.

    And if you are really worried about it from all the "advice" here, then you can put one GTI on one circuit and the other on a separate circuit. Some have had better overall results if they put two GTIs on each side of the 240V etc..

    I actually call my insurance company every time I need to use my 1200W microwave. I had the guy come out and check for the UL label several times in case it fell off. Man, if that sticker ever fell off I bet the house would burn down!
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Adding Wind to a Solar GTI system

    Because I am a literal kind of guy... NFPA Microwave fact sheet (PDF):
    Home Fires Involving Microwave Ovens

    During 2004-2008, U.S. fire departments responded to an average of 7,000 home structure fires per year in which a microwave oven was involved in ignition. These fires caused an annual average of two civilian deaths, 140 civilian injuries, and $22 million in direct property damage.
    • One in every five (19%) of microwave oven home structure fires cited appliance housing or casing as the item first ignited.
    • Microwave ovens involve more emergency room scald burn injuries than any other cooking device.
    • Nearly half (45%) of the microwave oven injuries seen at emergency rooms in 2009 were scalds.
    • Thirty-one percent of the scald burns and 14% of all microwave oven related injuries were scald burns incurred by children under five

    Want to ask about Clothes Drier Fires?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system
    fixer wrote: »
    Man nothing but kill joy.

    I say have fun, do it and learn. It's a hobby, let the guy have fun!

    500W... 800W... IT'S A HOBBY!!!!

    It's electricity; it is dangerous. If you do not understand that you should not be working with it.
    It's sad that you have to keep asking the same question over and over.

    Sadder still that we have to keep giving the answers over and over because people don't listen.
    I actually call my insurance company every time I need to use my 1200W microwave. I had the guy come out and check for the UL label several times in case it fell off. Man, if that sticker ever fell off I bet the house would burn down!

    Just because the sticker falls off your microwave doesn't mean it didn't pass the test to be UL certified as safe. That's far different from messing with things that never were declared safe. It is also far different from messing with things that produce electricity and feed into a another source like the grid which is capable of hitting you with enough zap to kill you.

    We have an ethical, moral, and legal responsibility to point out potential dangers with any and all equipment mentioned on this forum. That includes non-certified, illegally installed grid tie inverter set-ups. Electricity is dangerous. It can burn your house down. It can kill you. You do not "play" with it; you work with it. If you don't respect and/or understand this please refrain from posting your "advice" as it is ill-advised.
  • fixerfixer Registered Users Posts: 12
    Re: Adding Wind to a Solar GTI system
    We have an ethical, moral, and legal responsibility
    OK, so you are one of the owners of Northern Arizona Wind and Sun?

    You should let us know before giving advice on these things so we know what your profit motivation is for turning people away from DIY projects.

    So this forum is not for DIY people? Why not state that right up front?

    Is it just for product support for the Northern Arizona Wind and Sun company?

    Are there any other owners here?

    Thanks.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding Wind to a Solar GTI system
    fixer wrote: »
    OK, so you are one of the owners of Northern Arizona Wind and Sun?

    You should let us know before giving advice on these things so we know what your profit motivation is for turning people away from DIY projects.

    So this forum is not for DIY people? Why not state that right up front?

    Is it just for product support for the Northern Arizona Wind and Sun company?

    Are there any other owners here?

    Thanks.

    None of the moderators here have any connection with the host company, Northern Arizona Wind and Sun.

    Windsun and Rick, the administrators, are the company men. They do not tell us what to do or how to do it (excepting the rules they have set up for the forum, niel). There has never been any mention from them to "push product" or anything of the sort.

    What we are is knowledgeable and experienced in the fields of electronics and electricity. In my case 40 years worth of experience, and I'm not dead yet.

    Most of what we advise on here is DIY. But when we advise we advise wisely, and that includes warnings against unsafe and/or illegal practices. Anyone who chooses to ignore such advise does so at their own risk; the responsibility and liability is yours alone.
  • 20yrDCman20yrDCman Registered Users Posts: 23
    Re: Adding Wind to a Solar GTI system

    That is not true. Anyone who lives near the shore has wind. Wind turbines literally work for everyone of course some more than others. If you know you live in a low wind area just buy an inexpensive lower wattage turbine and put a lot of blades on it. You can generate 12v faster with a 24v turbine. You can generate 24v faster with a 48v turbine. In any case just fuse the turbine. You can always check with the manufacturer about the fuse necessary.
  • 20yrDCman20yrDCman Registered Users Posts: 23
    Re: Adding Wind to a Solar GTI system
    dlwyatt1 wrote: »
    Sarge you crack me up AND you are making me hungry!!! I'll pass on that video after I saw a news clip on the Nathans hotdog eating contest. I think the winning number was 54!

    Coot - totally agree that the branch circuit ampacity needs to be sized to handle the load. In my application, I'm looking at 400W of solar plus 800W of wind. That is only a little over 10A to the panel on a perfect wind/solar day - no problem there. The bus is sized to the rating of the panel so no issue there either. During the series of hurricanes we had here (Florida) years ago, we all had generators backfeeding into our house grid - YES with the mains off. The power company knew this and took precautions against the boneheads that didn't shut off the main breaker. Would do it again in a heartbeat. We had no power for long periods.

    GGunn - I'm not looking to install a Proven Energy 15KW turbine ( that's $25,000 on a $40,000 tower). If I was, I would run all the calcs to justify the ROI. I have an excellent book on designing mid size turbine systems that has all of the formulas. I'm talking $459 here and we do get a steady sea breaze that can actually be annoying at times. This is more for fun. When I move out West soon, I will go big time (10KW or larger) and do all the calcs - I promise.

    What I was really looking for in this forum was someone with experience stacking GTIs. DC voltage is DC voltage. Doesn't matter what the source is (assuming the trubine is rectified from 3 phase that is and properly loaded).

    Thanks all.
    You can stack gti's as long as you don't exceed the amperage of the circuit breaker in the panel.
    FYI with small wind turbines you can do a lot more for a fraction of the price. Just don't assume 1 turbine will do it all.
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