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Forum Index : Windmills : Grid Tie for Wind & Solar "LOW VOLT"
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wallablack Senior Member  Joined: 10/08/2011 Location: AustraliaPosts: 164 |
I have built a selection of wind turbines and have also purchased 2 x 120W solar panels. The wind turbine I am using now produces 2-4 Amps @ 1.5m/s and 12-14 Amps with good wind. My turbine is AC out and goes into a rectifier which converts it to 24VDC. My grid tie is good for 12-28 Volts but the problem I am facing is that my mill runs almost all day at a slow speed producing 2-6 Amps contantly but it not spinning fast enough to produce the 12 - 24V required to start the grid tie. How do I go about grid tieing my MILL so the 2-6 Amp "under 12V" goes into the grid. Is it worth it? My MILL grid tie is a cheap chinese evilbay jobs but it does do the trick as I have turned everything off and watched my meter run backwards during windy days. My solar panels on average run at about 18VDC @ 14 Amps but are on thier on grid tie which is not an issue. Foolproof systems do not take into account the ingenuity of fools. |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
18V DC @ 14 Amps equals 252 Watts, not bad from 240W total solar panels but I very much doubt that is an "average" run  Klaus |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Wallablack You can use a a boost module to go up to cut in volts they cut in at 10 volts and are good for 5 to six amps out you set the output volts below the generator volts when the wind is up and then they cut out at at the volts set and it then goes to the main rectifier feed, I have mine set at 26 volts and it will do up to 8/9 amps at that then drops off as the main rectifier cuts in with higher volts, the GTI cuts out at 30 volts and will load to 10 amps at that, you will need a controller to dump load or the mill will over voltage when the GTI shuts down and magic smoke will escape. Ebay Item number: 110723724780 You will need a diode on the input and the output to isolate the boost module otherwise it will back feed and not work properly. It will need a bigger heat sink, I used a piece of 38 mm angle 125 mm long on each side to replace the existing sink, it will work without it but gets very hot. You will need to put an extra cooling fan on the GTI as they do overheat and shut down or let out the magic smoke. I cut a hole in the top panel and fitted a 3 inch computer cooling fan 12 volt but powered through a 10 volt regulator of the input voltage, and disable the internal fan as it is useless anyway. Also put a CAP across the dc input 10,000uf 50 volt or larger as it helps stabilize the GTI As the old lady said every little bit helps. All the best Bob Foolin Around |
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| wallablack Senior Member Joined: 10/08/2011 Location: AustraliaPosts: 164 |
Sorry but I used the term "average" loosely. Without any logging gear it is impossible to have an average. I live in North Central Vic and we do see temps here of 45+ degrees and very long summers so we are not short of sunlight. I should re-quote by saying it not uncommon to see 14 Amps on any given day during summer. Foolproof systems do not take into account the ingenuity of fools. |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi wallablack, Its a bit hard to get a feel for these things over the internet, where do the 2-6 amps go if the Grid tie is not started and clamped to the grid? is it just a heat-sink somewhere or a dump load? I am surprised that your mill would be pumping out 40 watts or so and not have the voltage higher than that. it makes me wonder if your mill is seeing more than 1.5 m/s of wind and is being loaded by the inverter somehow and is stalling the blades. As an experiment you could unhook the DC inputs from your inverter and put them on a 12 volt battery, it would let you compare the AC voltages before the rectifier and see if there is an increase in voltage and a visual increase in rotor speed in light winds. edit (it needs to be light wind or you will not see the voltage change as the rotor spins up) If most of the light wind you get is during daylight and the inverter has the capacity to handle it, a small solar panel (70w) might be enough to give you the volts and amps to keep the inverter clamped to the grid. cheers Yahoo (please let us all know how you get on with your GTI.) NB I do a little work on a 12V off-grid system that has a 300 Watt chinese knock-off of the swea turbine on it. I am amazed at its performance in light wind. It doesn't like turbulence but give it clean air and it pumps amps all day. I'm confused, no wait... maybe I'm not... |
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| wallablack Senior Member Joined: 10/08/2011 Location: AustraliaPosts: 164 |
Thanks Bob, You wrote: "Also put a CAP across the dc input 10,000uf 50 volt or larger as it helps stabilize the GTI" LARGER in what sense? uf or Volt OR both? What sort of diodes are you using? Foolproof systems do not take into account the ingenuity of fools. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Wallablack Larger in uf, voltage will depend on your system voltage, SV x 2 is good. I use the 50 amp 1000v bridge simply because they are cheap and indestructible in this application, plus I had them on hand. All the best Bob Foolin Around |
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| wallablack Senior Member Joined: 10/08/2011 Location: AustraliaPosts: 164 |
I prob use the same rec, evilbay $5.00 job but 1000V 100AMP. My system voltage is 12V but soon to be 48V. SV x 2 is good???????? Confused....sorry  Foolproof systems do not take into account the ingenuity of fools. |
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MrDelanco Senior Member Joined: 12/11/2011 Location: United StatesPosts: 101 |
Hello Wallablack; VK4AYQ-(Bob) Is correct in using capacitor's to enhance your output. By applying a low voltage charge into an ultra-capacitor array, you will be able to build on the charge to a higher voltage. Ultra-capacitors from Maxwell Technologies are rated at 2.5V each. Each ultra-capacitor cell is rated at 2.5V each. There is no limit on the number of cells that can be placed in series to attain higher voltage's. A charge equalization circuit, called a balance circuit must be used. This is a standard design available from several source's. As the 1st ultra-capacitor charge's to 2.5 vdc the extra voltage is passed to the next ultra-capacitor to allow that cap to full charge and so on. By cascading this allow's the array to build too a higher output voltage using a lower input voltage. Here is the link too the balance circuit I built for my array. Ultra Capacitor Balance circuit Here is a link to the Ultra-capacitor test's I use an ultra-capacitor array to enhance the output from my slow moving cyclowturbine windmill. Here is a link to the Cyclowturbine windmill Good luck with your project. Regards Robert. MrDelanco:Project Videos It is not only too know what it does but to understand how it does what it does. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Wallblack SV is system voltage X 2 24 v0lt system is 50 volt cap. All the best Bob Foolin Around |
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| Xmaswiz Regular Member  Joined: 14/04/2011 Location: United StatesPosts: 69 |
would you mind posting the details of your cyclow turbine, how to fit and put to gether. I'd be inclined to try building one to play with. thanks Santa Maria, CA. Noel |
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| MrDelanco Senior Member Joined: 12/11/2011 Location: United StatesPosts: 101 |
Hello Noel; Darrieus machines with straight vertical axis blades are called Vawt's or Giro-mills a variant of the Giro-mill is the cycloturbine which uses a wind vane to mechanically orient a blade pitch change mechanism. Quiet, Silent, Eco friendly, will not injure birds or bats, no low pressure area created. I have a partial part's description listed in this forum. Recycled Items used to generate power. And you can view the Project Videos by clicking on the link at the bottom of my post. Cheers Robert. MrDelanco:Project Videos It is not only too know what it does but to understand how it does what it does. |
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