I acquired a SkyStream 3.7 from a renewable energy dealer who was no longer interested in selling the SouthWest product. The turbine was a demo unit with the "window" in the side of the Necel. The alternator proved to be good but the internal inverter board and relay board were no good. I guess they load failed QA inverters and relay boards into the demo units assuming that they will never see service anyway. So, I did two things. I aerodynamicaly altered the blade configuration for my low wind area. The strongest gust I have seen in this valley location after 20 years is less than 60 MPH. Sandy delivered a 54 MPH max gust followed by a 50 MPH gust in second place. The second task was to use an external inverter with the on board alternator. I chose an Aurora 3.6 for the job. I designed a DC power output circuit which uses voltage doubling technology and customed designed a relay based lockup board which locks down the turbine upon peak RPMs. A no load lockdown PRM is the lowest and a full fload lockdown is at a higher RPM. Currently the unit is being readied for a test stand where it will only be 12 feet off the ground for easy access and testing. The SkyStream is factory spec'ed for a 2.4 KW output, but my config will yield a peak of 6KW.

This is a video of the Skystream in a moderate wind with some details about it...

This video is the first thunderstorm hitting the Skystream from a direction that is open. It eventually causes a turbine trip to shutdown, a hoped for goal of this storm. It was nerve racking though because the first time anything could have happened....

This shot is looking into the back of the Necel with the heatsink top removed. You can see the large caps and relay board.

This is looking at the front. Skystream is a downwind machine. I have pushed the blade length out to 8 feet from 6 feet. This increases the sweep area by 80%. I used 304 stainless 1" square stock, 1/4" wall with custom 304 stainless brackets to hold the blades as they are held in the factory config.. This will increase the torque along with a smaller 6 foot diameter secondary rotor which will be downwind slightly from the main 3 blades. The seconday rotor has 9 blades configured for torque at low wind speed. The combination of the two rotors should yield very good low wind output. Please be clear, I am not going after power that is not present in lower speed winds as compared to higher speed winds. I am mearly maximizing the power curve skewed toward the lower end where more of my wind is.

This is the first version of the modified SkyStream. Blades are pushed out to 8' and a 9 blade (3' blades) secondary rotor is spaced between the 3 main blades. There will be much tweaking I am sure. The electronics package is working pretty well as well as the overspeed braking. I am working on developing the power curve which is very difficult to say the least. I have removed the secondary rotor to evaluate the main blade extensions first. Photos below show the lift up process.

1 ton chain hoist, going up...
Neighbor helping. Everybody had a hand on the chain hoist...

There are several changes to note here. First, the secondary rotor has been reduced from 9 blades to 6 blades. This was done for some weight reduction and to make a more equal spacing between the blades. The distance from any one main blade to either the secondary blade "in front" or "behind it" is now about equal to the distance between the secondary blades themselves. This makes much more sense. The extra 3 blades (removed) were really more of an interference than a help being almost on top of the main blades.

The second change is the nose piece has been placed on the hub. However, I added a "+" shape extension to the nose piece which helps to add rotational direction for the yaw. Sky Stream 3.7 in the small wind industry has the nick name of, "Wrong way 3.7". This is because one sees them many times pointing directly into the wind (180 degs off) as if they were an upwind machine, and of course not rotating. I analyzed this problem and came to the conclusion that three different factors were responsible for this. First the rubber vibration isolators above and below the support "disks" were too soft of a rubber. Second, there is minimal aerodynamic drag to prejudice the turbine one way or the other when it is directly 180 off correct direction in reference to the current wind. Third and more of an overall directional issue, leveling the turbine so it has no directional preference over any other direction is not an easy task.

Before I begin on direction issues, you can see I added a separate anemometer for the exact wind speed hitting the turbine. I have one on my weather pole 28' up and 50 or so feet away, but for power curve evaluation I needed to know the exact wind speed (at least as good as I could get) when comparing power outputs, RPM's and wind velocity.

Now for direction, I replaced the 8 top rubbers with custom made rubber washers from after market rubber coil spring spacers used on coil car springs. Their rubber is twice as hard as SS 3.7's rubber. WHY did I attack the hardness of the rubber?? After several days of observation, I noticed that when there was no wind and the turbine "sat" in the same direction for more than a half day or so, the rubber on the "heavy" side seemed to compress and show a "memory" effect, helping the turbine to favor the direction it HAD and IS in. This made it hard in light and moderate winds for the turbine to yield to the currect wind direction, particuarly if the "NEW" wind was opposite to the previous wind.

Close up of new snubbers...

I made some crude wooden jigs to enable me to "thin" the to thick coil spring spacers and drill the circle shape I needed for the washers. I also made a nose cone shape template for the 1/8" PVC 12" x 24" sheets I used to make the plus shape to add to the nose cone in an effort to give more "turn around" force to the yaw when facing a wrong way wind situation. I will evaluate over the next few days to see if the desired effect is attained.

Pout is the actual watts output to the grid. If you multiply Vin1 x lin1 x 2, you will get the input watts. Multiply that number by .95 and you will get the output watts or Pout. The column lin1 is the output current, but there is lin2 which carries the same current. So, you have to add the two currents together and multiply by the voltage to get the watts. The Aurora 3.6 inverter has two input circuits and I have them wired in parallel, thus they carry the same current. AS I verify the power curve into the higher wattages, I will post the data.... This was recorded during a thunder storm 4/19/2013. It was quite impressive to watch the turbine do an orderly shutdown when the 38 MPG gust hit it. I have a video of it almost to the shutdown point. The rain was hitting me so hard that I had to abort just before the gust and turbine trip. I have to say, I am very pleased with my engineering...!!!...

Last Updated 7/18/2024

2023 is another PV Record Buster !!


Its official! 2023 is also a PV production record buster. The main tracking array produced 18.887 MWH's which is about 1.1 MWH's less than last year. However, the gorund test array added another 3960 KWH's to that, totaling 22.847MWH's, an increase over last year of 2.249 MWH's total.

UPDATE 6/23: Kia Nero traded in for Kia EV6.


UPDATE 9/22: New 40+ KWH battery backup installed with coming 4.6KW direct feed array. See details under 'My Solar Home', Solar PV.



BLOG site for "open" topic writings, by myself!


Where to Find Us: (Fitch Consulting)

1072 Fowlersville Rd
Berwick, PA 18603

Phone: 570-752-4827




Peak solar production for my house in one day is about 130KWH.

What's New

01/12/2021 My new GEO heat pump is finally installed. I have been "tweeking" it until today, 01/16/2021. It works GREAT!! Unlike it predecessor's, it actually performs up to its submittal sheet. LOVE IT!!

I finally finished my electric overhead to underground conversion along with the transformer upgrade (15KW to 50KW).


May Monthly Production Record  Gets blown away in June at 2517KWH !!


Made changes to my PV tracking system. The main PV inverter was upgraded from an SMA SB-US-8000 to a Fronius Primo 11.4 (11,400 watts). Additionally, the PV arrays were upgraded with 20 SunPower 327 watt modules leaving 16 of the original Canadian Solar 255 watt modules, bringing the total output of the array from 9.18KW to 10.620KW. The combination of the inverter upgrade coupled with the array KW upgrade, should generate an additional 2 to 3 MWH a year. I hope this will compensate for the increased cloudiness being produced by Green House Gas Heating Climate change. It took a fair amount of work to do all this....


UPDATE: All 36 modules are being changed out which will result in an array output of 11,772 KW. On a very sunny year, 20 MWH should be within reach.


PV Yearly Production Numbers


2021 PV Production is 19.325 MWH which just misses the record breaker last year. Across the year, 2021 was much cloudier but crazy super sunny March made it almost even. Since the system has been running, we have produced over 129 MWH's total.


2020 PV Production is  19.375 MWH which is a new record buster.!! The only month that did not gen more than last year was October. Our usage was up due to more driving and general increases, which the increase in production was able to satisfy. That production defers about $2000.00 worth of power from the grid.


2019 PV Production is 16.787 MWH.

2018 PV Production is 12.463 MWH.

2017 PV production is 14.293 MWH.

2016 PV production is 15.629 MWH.

2015 PV production is 14.543 MWH.

2014 PV production is 7.711 MWH, first year partial production. 9.374 MWH were produced through the entire startup test phase of the system before certification.


2019 production was a record breaker, do to the upgrade being active for 1/2 the year along with being decently sunny. Most likely, if the array upgrade had been active for the whole year, 17 or 18 MWH's would have easily been had.


2018 production was the worst production ever, not only for PV but for all solar. The rain and cloud cover was unpresidented! WE blew right through the 13 Megawatt range and landed in the low 12's. An increase in array capacity might be necessary to adapt to the GH GH'ing realities causing climate change, to resore a slight electrical surplus.


2017 production down 1.34 MWH from last year. All months produced less except for December which is the cloudiest month of the year.... Ironic...


Electric  car miles for the fifth year are 15863 saving 690 gallons of gas at an avoided cost of $1932, bringing the five year total to  $9172.00. Covid-19 reduced mileage, but a third car (Bolt) and a third driver beginning in August, over turned the shortfall.


Electric car miles for the forth year are 14037 saving 610 gallons of gas at an avoided cost of $2014.00 bringing the four year total to $7239.00. Gas went up and down over the period.


Electric car miles for the third year are 13,220 saving 575 gallons of gas at an avoided cost of $1955.00 bringing the three year total to $5225.00. Gas prices steadily climbed throughout the year. Total number of gallons not used stands at 1790.


Electric car miles for the second year are 14,830 saving 645 gallons of gas at an avoided cost of $1870.00 bringing the two year total to $3270.00. Not bad for only 2 years at fairly low gas prices...


Electric car miles for the first year ran about 13,000 miles of energy free driving. The gas saved which would have been burned by the car that the Leaf replaced equals about 570 gallons at an avoided gas cost of $1400.00.


Total mileage across the three years equals 41,050 miles. At a gross electric usage of 3 miles per KWH year round, this translates to 13.68 Megawatt hours of electricity, or 4.56 Megawatt hours per year. With the addition of the Ford C-Max plug-in Hybrid over the last year, the total transportation electric load is increased by about 2 megawatt hours more, bringing the household trans electric yearly load to about 6.6 megawatt hours.