Skystream Battery Charging How To

April 18, 2013 · 3 comments

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The Skystream made by Southwest Windpower is a grid tie wind turbine that is designed to produce 240 volts AC at 60HZ (or 50HZ)  no matter what speed the wind is blowing.

skystreamIt does this by taking the wild AC from the alternator, rectifying it to DC and inverting back to AC.

It is quite unique as it is one of the few turbines that is truly plug and play. Simply connect the output of the turbine to a circuit breaker (like you would if you were adding a circuit to your breaker panel) and the turbine will do the rest.

The Skystream synchronizes with the power grid and starts pushing power into it, assuming the wind is blowing.

But what if you are off the grid and would rather charge batteries with your Skystream?

The good news is that it is possible. The better news it that it is easy assuming you have a sine wave inverter or inverters that make 240 volts at 60HZ (or 50HZ) and the inverter(s) output is at least high enough to handle the maximum output of the Skystream (about 2.5kW).

The Skystream needs to have a grid to push power into. Fortunately you have your own mini grid.

All you need to do is back-feed an AC breaker in your power system’s breaker panel, the same as you would in an on grid system. It is called AC coupling and is not very well known. The reason it works, is all the high end inverters (such as Magnum Energy, Outback Power, Xantrex/Schneider) are bidirectional. Normally, the power flows from the batteries through the inverter to the AC breaker panel. It will also flow from the AC breaker panel through the inverter to the batteries. In fact, charging your batteries by sending AC back through the inverter is very efficient.

When the Skystream turbine begins to push power into “your grid” the power will flow:

  1. To any loads you might be running like a fridge, freezer, lighting or whatever.
  2. Through your inverters (backwards) and charge the batteries.

The inverters will operate in reverse at the same rating as they operate normally. If you have a 4000 watt inverter, you can send up to 4000 watts back thru the inverter.

Although this method for battery charging works very well, there is one issue.

The batteries can be damaged if they are allowed to overcharge, as when the wind is blowing after the batteries reach a full state of charge.

But won’t the inverter(s) limit the current and act as a charge controller as the batteries reach a full state of charge?

No they will not. Although they have a charge controller built into their battery charging system it has nothing to do with AC coupling.

If you decide to AC couple a Skystream you must protect your batteries from overcharging!

You can protect your batteries by one of the following methods:

  1. Add a dump load to your system (preferred method)
  2. Add a circuit to disconnect the turbine when the batteries are full

Using a Dump Load with Skystream Wind Turbine

The best option to protect your batteries is to add a diversion load. If the batteries are full and the Skystream is still generating power, the power will go into the diversion load instead of overcharging the batteries.

General information about dump loads (diversion loads)

How to add a dump load to your Skystream (including diagrams)

Disconnecting the Skystream When the Batteries are Full

The Skystream in a very unique piece of equipment. As we have mentioned it has a built in inverter that connects to the grid automatically. If the turbine is not connected to the grid, a brake is applied. When the Skystream comes out of the box you will notice it is almost impossible to spin the rotor. That is because of the brake.

When grid power is applied, the Skystream will synchronize with the grid and release the brake. This takes about 5 minutes from the time gird power is applied. If the grid goes down for any reason (such as a wind storm, broken power lines)) the brake will be applied immediately to protect the turbine from over-speed. This is what sets the Skystream apart from all other AC wind turbines. The other wind turbines would over speed and be damaged if removed from the grid.

The second method of protecting your batteries from overcharge is by simply opening the circuit between the Skystream and the inverter(s).

This can be as easy as turning off the breaker, however that would not be automated.

Click here for instructions to automatically disconnect a Skystream to prevent battery over charge.

Leave a Comment

{ 3 comments… read them below or add one }

Claude June 13, 2016 at 6:08 pm

Hi where can we by a Skystream ?? we live in New Brunswick Canada


Jody Graham June 14, 2016 at 2:50 pm

Hi Claude,

I too live in New Brunswick and it is difficult to find products in this area of Canada. I used to operate a medium sized solar store here but an illness forced me to shut down. I still have all the connections in purchasing items at wholesale but none of the Canadian wholesalers would stock a Skystream. I have a unit here I used for a display when going to solar conferences or training. It has never been in the wind but it is not new in the box either. I have two sets of blades. It is a long story but I ordered 2 units and one of the generators got damaged badly in shipping. The blades were fine but I never got the generator repaired. Are you planning on making your own tower? Where are you in NB?

I eventually planned to install the Skystream here as a demo and back-feed it into my off grid power system as a sample of a grid tied wind turbine. We have been off grid here since 2001.
I am in Zimbabwe, Africa right now training solar installers but will be home near the end of the week if you want to talk. I could try and find you a unit through one of my suppliers in the US. They are not cheap but much cheaper than buying in Canada. Let me know about the tower and where you are and when I get back we can go from there…Jody

You can contact me by going here.


Tzortzina June 13, 2013 at 6:31 am

I was wondering about an EMP and solar cells. Maybe a copper grid would offer protection, like a faraday cage. I wonder how much sunlight would be blocked by the screen. Also I have a bike frame a 120 amp auto alternator ( Soylean Green ). Each application requires its own excitation ( regulator circuit ) but I think it would work on cloudy or snowy days. Thanks for all your info, and I say Thank You to all the vets and their families. God bless you all.