Discussion in 'Connecting to the Grid' started by WindyFAQ, May 14, 2012.

  1. WindyFAQ

    WindyFAQ WindyNation FAQ Staff Member

    I use about 2000 watts per hr according to my electric bill on my highest month; around 1300kwh in 1 month. I have almost constant wind in the 12 to 25 mph range. How much can I realistically expect to lower my usage per windmill?
  2. dlmcbm

    dlmcbm WindyNation Engineer

    I will take a stab at this but remember there are so many variables to take into consideration. Lets say you get the 750.... in about 20mph wind into a 24v battery bank it makes about 250 watts. I would assume you are going to use a GTI so we will put total efficiency at about 80% given the generator, wiring, distance to house, GTI etc. so we are at about 200 watts. IF you will have this wind 24/7 that would total 4.8kwh per day, 33.6 per week, and about 150kwh per month. Keep in mind that it can go UP or DOWN drastically depending on the wind speed. I would tell anyone that has a good location for it to go with a hybrid wind/solar setup. Solar is more predictable but wind is great at night and the winter time. If my numbers are off I hope that someone will correct me.
  3. windyguru

    windyguru WindyNation Expert

    I will use the Windtura 750 and a 16 mph average annual wind as an example to calculate this. Note, I chose a 16 mph annual wind to make the math easy because the Windtura 750 does about 200 Watts into a 24V battery bank at that wind speed.

    First off, grid tie inverters are more efficient than battery bank charging because they use Maximum Power Point Tracking (MPPT) algorithms to maximize the power produced by the wind turbine. If you are connected to the grid with a MPPT grid tie inverter, you can expect about a 20% increase in power production. For the Windtura 750 at 16 mph, this increases the power production to about 240 Watts (a 20% increase from 200 Watts).

    Now calculate kwh power production for the Windtura 750 at a 16 mph annual wind speed:

    At 240 Watts, it takes 4.17 hours to put 1 kwh into the grid ( 240 Watts x "hours" = 1000 Watts and if you solve for hours you get 4.17 hours).

    There are 24 hrs/day x ~30 days/month which gives you 720 hours in a month.

    If it takes 4.17 hours for the Wintura 750 to put 1 kwh into the grid in a 16 mph wind, how many kwh does it put into the grid in a month if the average wind speed is 16 mph?

    Answer: 720 hrs/(4.17 hrs/1 kwh) = 173 kwh into the grid per month

    At an approximate cost 0f $0.12/kwh this means that the Windtura is feeding about $20.76 into the grid per month. (0.12/kwh x 173 kwh = 20.76)

    If you consider all the local and federal tax incentives, the return on investment (ROI) is not that bad.

    You can follow the steps in this post to calculate the approximate kwh produced for any wind turbine at any wind speed as long as you have access to a reliable power curve ( Power vs. Wind Speed).
  4. timber

    timber WindyNation Engineer

    Thanks Windy,

    It's nice to see this as a formula to make the calculations easy.
    It's also great that you provide (realistic and tested) power curves for the products you offer.
    A search of any of your products on this forum will also provide a variety of applications and equipment used to further help in deciding which combinations will work best for a particular situation.

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