I don't understand the figures here. If one assumes that you can sell you electricity for 7pence and get an additional 3 pence for the ROCs then you can earn an average of 10pence per Kwh. To earn the expected payback of £450 would mean production of 4500 Kwhs a year. This is a very debatable claim. As there are only 8760 (24*365) hours in a year, this seems to assume the turbine would be operating at peak output half the time. This is nonsense.
I support small-scale machines and wish more people would have them, but don't want people to feel let down by unrealistic claims of their "rule of thumb output"
|Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Stack Up In Reality?||Stuart - 2006-10-05 16:58:15|
|Re: Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Live Up To To The Sales Hype||Stuart - 2006-10-05 16:59:34|
|Re: Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Stack Up In Reality?||Stuart - 2006-10-06 14:10:14|
Paul Gipe's comment: from http://www.wind-works.org/
Thus, manufacturers who say you will get an average of 6 m/s on the roof at your site and this will generate 1,000 kWh/year from a 2-meter diameter wind turbine will overestimate production by 10 (ten) times! Those that say you can get 2,000 to 3,000 kWh on your roof top will overestimate your production by 20-30 times!
|Re: Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Stack Up In Reality?||Ted Marynicz - 2006-10-11 21:02:15|
I too am most concerned about the claims made by some manufacturers which seem to be misleading in the extreme.
I've done some calcs that show that a 1.75m diameter turbine is only likely to produce about 1,100kWh with a mean annual windspeed of 5.5m/s. This is unlikely to be the sort of speed that anyone in a built-up area is going to get on their roof. The figure drops to about 300kWh with a mean speed of 3.5m/s. (This is based upon a conversion efficiency of 35% - which is what small turbines have been found to achieve when tested.)
There has been talk of independant testing and government certification for such claims but nothing has transpired yet. Some system along the lines of the mpg figures for cars is needed and needed quickly.
B&Q are now selling the Windsave turbines (not sure if any have actually been delivered yet though) "subject to survey". I would love to know how they determine the windspeed on peoples' rooftops. If they are just using the DTIs NOABL figures then I think they will be little better than meaningless in urban areas.
The whole situation could end-up giving the domestic renewables industry the same sort of reputation as enjoyed by double-glazing salesmen.
|Re: Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Stack Up In Reality?||Stuart - 2006-10-12 09:45:55|
Yes a standard measure of the output of turbines is needed. As you suggest if one follows the MPG example you could have one measure in ideal circumstances with very low roughness and another in an agreed higher roughness. This would allow people to make informed decisions about what returns they can expect.
This is probably something the British Wind Energy Association would be prime placed to implement as a voluntary code, before government regulates instead.
|Re: Are The Claims Of the Sellers Of Micro Roof Top Wind Turbines Going To Stack Up In Reality?||William - 2007-03-09 13:26:09|
Hi I am in the process of becoming an accredited installer under the Goverment Grant Scheme for Wind turbines followed by PV and would like to hear from people who have Systems installed to gather information on the Outputs given by the makers of the systems and what you are actually getting. Reason being I can give customers honest answers as opposed to Average figures etc.
I know there are a lot of variables especially for wind but it would give me some idea what actual installs are producing as I do not want to rely solely on figures produced by the makers bearing in mind that a turbine in the right location with the right wind speed will produce what the makers claim.
Thanks in advance for any info.