Report on Energy Loss In Bergey 10 kW turbines (Interim)

[Mel Tyree]

Hi all,
Readers of SWIEP will know I have suspected 10 to 20% energy production losses in 10 kW Bergey turbines GridTied by Xantrex's GridTek10. Mike Bergey thinks the problem is small (1 or 2% losses) and hence has ignored the problem so far. In my current study I have logged >20% kWh losses in the first 69 days. Interested readers may download my report R#40 from http://www.ualberta.ca/~mtyree/SWIEP/Publications.html You may also want to look at an earlier report R#12. This problem, an apparent design deficiency, might be corrected when Bergey releases their new turbine/inverter. Their new inverter was UL approved about 10 days ago but so far SWIEP has no specific information.
I hope to get access to a new system for testing purposes. If someone buys one and would like free testing please let me know.
Email me if you want some data on an Excel sheet.
--Mel
Mel Tyree, BA PhD (Cantab.) LLD (h.c.) FRSC

[Rob Beckers]

Interesting report Mel, also interesting how manufacturers deny any problems as a default reply. The unfortunate truth is that the small wind industry still has much growing up to do. Problems and misrepresentation that would never be tolerated in another industry (imagine your car didn't work 20% of the time!) are still common.

Other 10 kW turbine manufacturers simply use an off-the-shelf inverter (ARE uses the WindyBoy series for example). It would seem Bergey could simply solve their issues by doing the same.

-RoB-

[Mel Tyree]

Rob,
Thanks to you, Nando, Liuchen Chang and Andy Knight for assistance and comments regarding the attached report.
I used a 4 channel Tektronix digital scope, 2 differential current probes and 2 current probes to measure the efficiency of power conversions between my Bergey Excel 10 kW turbine and the grid. I give efficiency data, performance data, sample waveforms and more information about the conditions under which the GridTek10 stops producing power when wind speeds exceed 16 m/s.
My original report above shows that energy loss due to this defect in design is >20% but this figure may increase or decrease as the 8-month study progresses.
Best regards,
Mel
PS- if you want some data in excel files you will have to go to: http://www.ualberta.ca/~mtyree/SWIEP/Publications.html to download a file too big for Green Power Talk.

[Rob Beckers]

Mel, I continue to be fascinated by your willingness to go to great lengths to get to the bottom of an issue, not to mention your thoroughness of investigating.

One wonders though, at this point wouldn't it have been cheaper to just replace the Gridtek inverter with a couple of Windyboys or Auroras, and be done with it? :confused:

-RoB-

[Mel Tyree]

Rob,
There is a lot of merit in what you say. Why am I waiting? Probably I will switch over to Aurora or WindyBoy inverters within the next year. But, first, I need to document energy loss for a year and then do a cost-benefit analysis to see if it is worth making the change. Why am I doing this?
(1) I am learning a lot about power electronics and turbines. I think research into sustainable energy devices (wind turbines and PV system) will be my retirement occupation. So I have to learn the 'trade' first.
(2) SWIEP is a consumer reports group. I want to provide factual information to other owners of GridTek10 so that they too will know if a switch is cost-effective.
(3) Perhaps I should wait to see what kind of new inverter Bergey offers. Their new inverter will shortly go thru beta test at ASU.

On the other hand, it seems I am doing a lot of FREE R&D for Bergey. Shouldn’t I get paid for this?:idea: I know, they don't have much $$ and maybe don't want to know?

--Mel
Rob,
There is a lot of merrit in what you say. Why am I waiting? Probably I will switch over to Aurora or WindyBoy inverters within the next year. But, first, I need to document energy loss for a year and then do a cost-benefit analysis to see if it is worth making the change. Why am I doing this?
(1) I am learning a lot about power electronics and turbines. I think research into sustainable energy devices (wind turbines and PV system) will be my retirement occupation. So I have to learn the 'trade' first.
(2) SWIEP is a consumer reports group. I want to factual information to other owners of GridTek10 owners

[Mel Tyree]

Hi all,
Brent Summerville at Appalachian State University has just released a new power curve for the Skystream. The folks at Southwest Wind Power have been tweeking their control software and they have managed to improve the power curve significantly (about 20%). The thing I also like about the Skystream is that it does not cut out production at high wind speeds hence will not suffer the loss of energy production like the Bergey Excel + GridTek10 combo (R#40 and R#42 of SWIEP). After 86 days of testing starting on 1 Sept, my Bergey has lost about 20%.
I have visited sites with Skystreams installed and have seen them NOT turning on windy days. It seems that earlier versions, at least, have been prone to problems such as generator burnout and inverter problems. I presume that these issues have been addressed too given that they have been on the market for a few years now. The Skystream is a great alternative for people wanting a small wind turbine in their backyard. There are other good choices too as Rob knows!
See R#43 on http://www.ualberta.ca/~mtyree/SWIEP/Publications.html
ANYONE who owns a Skystream in encouraged to provide consumer feedback via SWIEP.
--Mel