Dan and Dan attended the MREA Small Wind Conference last month in Wisconsin, then stayed to give a couple seminars at the Energy Fair. It was great networking (and drinking beer) with all our friends in the small wind industry!

At the fair, we visited a booth hosted by Ginlong Technologies. They have a new product that is just being released for the US market….a 2.2 kw direct grid-tie inverter for wind turbines. They have a 6.6 kw and 11 kw also. The MSRP for the 2.2 kw is only $900! The inverter is listed for Canada and Europe, and the UL listing for the USA would be happening “any day now,” they told us.

This is pretty exciting news, as until now Magnetek and SMA were the only options for direct grid tie (see our other post on this blog for more detailed information). We have heard reports that both of these companies are a bit reluctant to provide a warranty for their inverters when connected to a homebrew wind turbine; Ginlong has no such problem.

As you probably read in our earlier grid-tie post, a direct grid tie inverter (no battery bank) for wind turbines must be programmed with the power curve of the turbine. Instead of having to use a laptop and special software, you can program the curve on the Ginlong from the front panel display, with LCD ’sliders’ that look like a graphic equalizer for a stereo. This makes it very easy to deal with, and you can tweak it in real time so your turbine is running just right at all wind speeds. Also, it can accept input from 30 to 750 volts DC, a very wide range — though of course you would want to wind your stator for a fairly high voltage (250 volts is probably about right).

Also, many of our friends in the small wind industry told us that this company is VERY reputable and does NOT sell crap, unlike some of the current Chinese wind turbines on the market.

We don’t have experience with the Ginlong inverter yet, since we are both located miles off grid. But if you DO try it, please drop us a line with your report!

DAN and DAN

This one is now the most frequently asked of our frequently asked questions!

The answer is — yes you can. Details follow.

• With an Islanding grid-tie system, you would simply wind your turbine’s stator for your system voltage (battery bank voltage).
• (An islanding grid-tie system is one that uses batteries for back up.)
  
• After your grid-tie system is inspected, permitted, approved and turned on by the power company, you would wire your turbine into the battery bank just like you would do in an off-grid system.
• The system would not have a diversion load controller running heating elements, though. Instead, your grid tie inverter gets rid of extra power by selling it to the utility.
• UL listing is not generally a problem–there are no UL standards for wind turbines anyway. Only your grid-tie inverter and it’s associated disconnects, wiring, etc. would need to be UL listed.

• With a non-islanding grid-tie system, (also called “direct grid tie”) you will run into all kinds of hassles and expenses, plus a bit of risk (more below)…
• (In a non-islanding system, there are no batteries, but if there is a grid blackout, you then have no power for your house even if the wind is blowing. Ouch! That must be a frustrating experience!)
• There are two inverter products out there for direct grid-tie of wind turbines: The SMA WindyBoy and the PowerOne Aurora. Since the authors both live off-grid, we have not tested either of them.
• You would need to wind your wind turbine’s stator for higher-voltage output; this is easy to calculate and scales up directly from turbines for islanding systems, and the information is available from the inverter manufacturer’s websites. For example, the SMA inverter needs 150 volts DC coming in before it will even turn on.
• Here’s the problem—both the SMA and the PowerOne need to be custom programmed at the factory to match the power curve of your wind turbine. Not a problem with big wind turbine manufacturers, as all the turbines that come out of their factories are identical. A big problem with home builders, since every turbine will be different.
• These large inverter companies are not willing to provide this service for each individual home builder, at least not at low cost. You would need to ship the actual alternator that you built to them, and pay a hefty fee….if they were willing to even touch the job.
• Here at our wind turbine shop, we produce quite a few turbines. It’s likely that we will pursue getting a custom firmware program for our machines in 2009….but that doesn’t help the home builder at all! If you used the (not yet existant) program for our machine and your machine performed even slightly differently than ours, the inverter program would be wrong, and your turbine, your tower, and your fancy new direct grid-tie inverter would be at risk. And you would likely not receive warranty service on the inverter.

Conclusion

So, in conclusion — Stick with an islanding grid-tie system and you’ll have no troubles at all. For direct grid tie — good luck, an be sure to factor in the cost of shipping and programming (if even available) to your initial investment and return on investment (payback time). And when it’s windy outside, your turbine is cranking out 1000 watts, and your house goes black because the grid went down and you have no battery backup………come over for a beer, because OUR lights will be on!

UPDATE 4-20-2009

Some of you have been following direct grid-tie discussion on the AWEA mailing list and other discussion boards. And have pointed out that Hugh Piggott successfully direct grid-tie a homebrew turbine in France. Here’s the scoop:

Homebrewers have now successfully done direct grid tie with no batteries using both the PowerOne (Magnetek) and SMA units. The factory can set a ‘generic’ wind turbine program for you based on your swept area, it will be very similar to programs for similar sized commercial turbines. Then, using your laptop, you can “tweak” the program to best match your performance. We would recommend starting with the alternator performing too ’stiff,’ stalling the blades, and then working back towards better performance.

Here’s the hitch — you will need to convince your SMA or Magnetek dealer that you know what you are doing. You may also NOT be successful in getting a warranty on the inverter, this seems to depend on how convincing you are about your skill level. AND, keep in mind that the responsibility of preventing an overvoltage condition is entirely yours….neither of these inverters warranties, if you can even get a warranty, will cover damage from overvoltage caused by a  homebrew turbine!

If anyone takes on this project, please do post your successes and failures here!

DAN F