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Forum Index : Windmills : Grid connect
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Fernbrae Newbie  Joined: 06/10/2007 Location: AustraliaPosts: 7 |
Dear Members , I am new at this subject but have been using some forms of Solar power for some time now . I am asking what are the minimun requirements that are needed to connect to the Grid. I am well aware that a pure sine wave inverter is required and solar /wind generation is need ed to power the inverter but as yet have not found the required wiring design to adapt to the grid . Any help would be gratfully appreciated. regards Greg Living loving life always |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Hi Greg You really need to talk to your local power authority first. They will tell you if its allowed with their power network, and if so, what equipment ( Make, Model ) they will accept. Also remember grid connect inverters are expensive, and it will take many years to recover the costs. I'm surprised any power companies allow grid connect inverters. A big concert for the power authority is power outages and maintenance. If they need to do work on your street, they may turn off the power to make it safe for their workmen. But if someoe on the street has a grid connect inverter, then they will need to make sure its also shut down and locked out. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Gizmo, All grid connect inverters in Aus have to comply with the Standards. The only issue I can see with Grid connection and the maintenance of the utility is when the number of independent grid connect power sources in an area becomes the dominant supply of power. This may interfere with the grid guard mains side of the inverter, detecting the power being disconnected by the utility. I am not in a position to speculate on what percentage of the total utility supply that this may occur. This aspect must have been considered by the utilities. I live in an area with frequent power disturbances and many times my grid feeding inverters have shut down, with my windmill and solar systems having to shut down as the battery has become fully charged and there is no where for the excess power to go. When the grid is restored, the systems reconnect. The cost of an inverter may seem significant. The utility ETSA, is planning to increase power charges by 30%. RE payback is a long term investment. The power costs keep going up and this reduces current RE users payback time. The inverter service lifetime is a component that is still relatively unknown. I have no regrets with my RE systems. I may have to pay tax on income derived from selling excess power though. cheers, Gordon. become more energy aware |
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| Evil Roy Slade Newbie Joined: 14/01/2008 Location: AustraliaPosts: 11 |
Esteemed Forum Members, Is there a mechanism on grid tie inverters that allows the amount of current drawn by the grid to be controlled? Or is it that once the inverter's cutin voltage is reached the grid will sink max power from the inverter until the input source is unable to maintain voltage and therefore cutout. Would this not mean that the inverter would be cutting in and out rapidly? Am I missing something? TIA ERS |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi ERS, I had to control the current I supplied from my battery to the GTI(grid tied inverter). Initial testing showed the GTI would take all it could get from the battery, up to the GTI max power. There needs to be an impedance matching component. I was able to use current limiting and loose voltage regulation to convert the impedance of the battery to match the output of my solar panels. The windmill still has to shut down if the grid connection fails and the battery is fully charged. Without the matching components, my system did oscillate. The anti islanding protection delays will predominate. This is why the wind, grid connected systems I have experienced will in certain conditions fail to supply power to the grid, even though there should be enough wind energy to do it. I would check individual inverter firmware parameters to see if something could be tweaked. cheers, Gordon. become more energy aware |
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| Evil Roy Slade Newbie Joined: 14/01/2008 Location: AustraliaPosts: 11 |
Hi Gordon, Thanks for your tips. The system I am designing will not have a battery but a load controller between the generator and GTI. I have emailed various suppliers to see if they have a built in current limiting facility. Otherwise I will have to put the limiting feature in my controller. Will let you know what replies I get...(if any!) ERS |
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AMUN-RA Senior Member Joined: 10/03/2007 Location: AustraliaPosts: 144 |
Most GTI are mppt controllers to get the most from your panels y do you want to limit it the sun is free energy & by the way Gravity sucks ex skydiver Mick.  Every day the sun shines & gravity sucks= free energy. |
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| petanque don Senior Member Joined: 02/08/2006 Location: AustraliaPosts: 212 |
As I understand the sunny boy inverter is approved for grid tie With a software conversion they are suitable for windmills. They are then sold as a windy boy. |
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| Evil Roy Slade Newbie Joined: 14/01/2008 Location: AustraliaPosts: 11 |
As yet I have received only one reply and that was from SMA Sunnyboy. The short answer is they have no external control on their GTI to control outgoing power. Yes they do have MPPT but not suitable for wind generated power and I prefer to use my own algorithms anyway. So now its time to scratch the head and come up with some impedance matching stuff (thanks Gordon) to put on the front end of the inverter. Oh well, if it was easy it wouldn't be fun right?! ERS |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi ERS, Impedance matching and GTI. I could give you an idea of how my system works. You can contact me if you like. cheers, Gordon. become more energy aware |
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| Evil Roy Slade Newbie Joined: 14/01/2008 Location: AustraliaPosts: 11 |
Post Deleted |
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