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The two most commonly exploited sources of natural power today, in domestic situations, are wind and sun.
Hydropower is used in remote locations but is much less common and more specialized so we will cover only wind and sun here.
You will quite often see wind turbines and solar panels on narrow boats, caravans and other remote dwellings.
I will explain the basics of these systems here in the best I can, I hope this will be of some help.
Lets start with:

Wind turbines

When a magnet passes a coil of wire an electrical current is induced in the wire.
The current increases to a maximum dictated by the strength of the magnet and the number of coils in the winding then falls away to zero again.
A wind turbine has several coils and magnets in it and creates A.C. (alternating current). That is to say the current flows first one way through the coil, then the other, unlike a battery, which, by means of a chemical reaction gives us D.C. (Direct current?it only flows in one direction).
There would be no current produced if the magnet was to be in a stationary position, even if it was next to the coil.
So we use the wind to turn the blades, which in turn, turns the shaft they are fixed to. The magnets or the coils are attached to this shaft. (It doesn’t matter if we move the magnets or the coils).
The current from a wind turbine also increases and decreases as the wind increases and decreases, no wind?no power!
This is of no use to us unless we are prepared to wait for the wind before using our appliances and even then as the current isn’t constant it would be no good as lights would burn dimly one minute and possibly explode the next!
So the way to over come this problem is to store the energy we create.
This is best done with batteries.
Batteries produce D.C. (direct current), though, and in order to charge them we need D.C. power, not the A.C. that the wind turbine gives us.
The answer to this problem is the ‘bridge rectifier’. This is four diodes (which are semiconductors) configured in a particular way, see fig 1a the symbol for a diode & 1b the symbol for a bridge rectifier.

The electricity can flow only in the direction that the arrow shows, it cannot flow the other way. So if you look at the diagram of the bridge rectifier you can see that flow is made to go in a particular way through the rectifier. The top and bottom terminals are where the A.C. from the wind turbine is fed. The left and right terminals are the positive and negative, D.C. out. Remember that the A.C. current is flowing back and forth.
Don’t worry at this point if you don’t understand the bridge rectifier, just remember what it does?turns A.C. (alternating current) into D.C. (direct current).
Note that I am talking about single phase here. A lot of modern wind turbines are three phase. The principals are more or less the same, it just gets a little more complicated!
The ‘Rutland’ wind turbines made by Marlec have the rectifier built in and so make life a lot easier for us! All of their modern units have three phase generators in them as they are much more efficient than single phase. So in this case we already have the right kind of current to charge our battery/batteries.
The next thing to be aware of is that the battery can be charged too fast and /or over charged (charged for too long), if there was nothing to control the input to the battery.
The answer to this problem is to fit a ‘regulator’. This goes between the wind turbine and the battery. It controls the voltage and the amps going into the battery and senses when the battery is full. When the battery is fully charged the regulator will divert the power to a ‘shunt’.
If when the battery was full we simply disconnected it, the wind turbine would have no load on it and could spin out of control in a strong wind and be damaged.
So we use a shunt, this is quite often just a coil of wire that is in effect a heating element.
The excess power produced by the wind turbine is turned into heat, which is dissipated into the air. If the excess energy is enough we could use it to heat something like water, for domestic use.
I have a friend with a 5kw wind turbine that is diverted to under floor heating in the kitchen when the battery bank is full. In the case of heating the fluctuating power caused by the wind fluctuating doesn’t matter so much. Now we have the energy from the wind stored in our batteries we can use it when we want.
Things like lights can be 12v and so we can run them directly from the batteries. We can also run other 12v appliances like a small T.V. and or stereo etc.
But if we want to run something that takes mains power (240v A.C.) we need yet another gadget, the inverter.
An inverter turns 12v or 24v or 48v D.C. into 240v A.C.
All these electrical components need to be the correct rating i.e. if your wind turbine gives a maximum of 60 amps then the rectifier and regulator need to be able handle 60 amps (at least, it’s best to have over rated components.
You need to decide if you are going to use a 12v 24v or 48v system as well.
Inverters, wind turbines and regulators are all available for these different voltages.
Basically the further you transmit the electricity the higher the voltage needs to be.
So if your wind turbine is only a few feet away from the batteries and your home is next to them, then a 12v system would be fine. But if any of the components are a long way apart the higher voltage systems may be needed.

Solar Panels

You can also use solar panels to generate electricity.
The way it does it is too complicated to explain here and also not that important at this stage.
Solar panels are a little simpler to use, mainly because they produce D.C. and there are no moving parts.
There are two main points to note with the solar panel (electrically speaking).
Firstly they are at their most efficient at around 16-17v, but when you connect them to your batteries you drag the voltage down (batteries can act as regulators under certain conditions).
If the solar panels are forced to run lower than the optimum voltage you wont get the best out of them so you can (if you want) add in between the panel/s and the batteries an optimizer that keeps the panels at their favorite voltage but puts out the correct voltage for the batteries.
This also applies if the sun is really bright and the voltage rises above the optimum voltage.
If you are running a ‘hybrid system’ i.e. you are using wind and sun, the regulator that stops over charging must be the last in the chain before the batteries.
Secondly it’s a good idea to put a blocking diode in the output of a solar panel to stop back feeding when there is little or no light.
The regulator will most likely do this.