Converts Sunlight "DIY" Solar Panel and Wind Power reviewed

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1. 

   Ed W says:

   June 8, 2014 at 5:18 pm (UTC 0)

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   One if the wind blows. I have a 15kw standby generator and I cannot put everything on it.

2. 

   Mr. Un-couth says:

   June 8, 2014 at 6:11 pm (UTC 0)

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   Twenty kW is twenty kW it doesn`t matter if it comes from a conventional 60 cycle commercial power source, a 25 kW wrist watch battery with a 80% efficient DC to 60 cycle ac converter connected to it`s output terminals, or a 20 kW wind driven turbine generator.

   One home would probably be a little bit too big of a load for the 20kW wind driven generator on a relatively still day.

3. 

   Ecko says:

   June 8, 2014 at 7:08 pm (UTC 0)

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   A curly question.

   Production of wind generator…
   A wind generator has a threshold to start generating, like 12km/h.
   It may generate 50% output at 18km/h and 100% output at 24km/h.
   These figures depend on the design.

   Wind availability…
   In what is called a “good/excellent location” for wind, the penetration may be 30%. That means the total production is 30% of the full rating. That means 6.6kWh x 24h per day, averaged over a year. This is very dependent on the site, winds, time of year and the wind generator itself. Call that 160kWh/d.

   Load per house…
   The average load is a vague thing, perhaps something between 3 and 24kWh per day (or any other number snatched from the air). This depends very much on the community, the culture, the location and the time of year. It is also a statistical measure, not an indication of the peak power demand at particular times. For example, do the houses have air-conditioners, clothes driers and heaters. Does everyone switch these on at the same time each day. This is still a rate where the houses take some care with electricity use. Divide your electricity bill by the rate per KWh and the billing period in days to see how you compare for KWh/d.

   At that rate, we could hope for 160kWh/d / 24kWh/d etc, so between 7 and 50 houses (on average over the year). This analysis gives no guarantee there will be enough power at any particular time. The excess power to demand at any particular time also needs to have a place to go – some sort of storage system. Batteries for even this modest power level would be huge, but also difficult to determine exactly how big without actually trying it out. For the feel of it, to store a day’s good operation, perhaps say 160kWh/d. Let the battery be 240V, it would be 666Ah capacity. A typical car battery is 12V at 40Ah.

   This power we are talking about is only useful when the houses are statistically averaged (they don’t all switch their heaters on together). It should be seen as a fuel saver for the existing power system. How much fuel is saved depends on , the way electricity is used in the houses, and when the wind happens to generate electricity.

   It works must better if the wind generator is connected to a grid where there are a lot of houses (many thousands) over a large area, say one or two states in the US. The connection uses a special inverter that can regenerate the energy from the wind generator at the correct phase and voltage to export power to the grid when required. This distribution over geographical area and a large number of houses evens out the load variations. Basically the wind generator exports power to the grid to supplement the power the grid gets from other sources. This is perhaps the best way to achieve a meaningful result, though if done on a grand scale the grid itself may have stability problems that come from the base load steam stations not being able to vary their output quickly. The bigger the variety and the geographical area the more likely that the system works, but individual lines in the network need to be considered too. Not simple.

   If there is no grid, like on a small island, the next best thing is to continuously run diesel generators that are specialised in that they can run for extended periods with small loads when the wind is good, and instantly take over when it is not good. Once again the wind generator is a fuel saver, but less effective because the houses may all increase and decrease loads simultaneously. The diesel generators must be big enough to generate the full load at some times, and there may not be enough load to use all the wind generator output at other times.