Wind and Solar - A Perfect Match for Charging Batteries

We have been using wind turbines for about 6 years to supplement our solar generation for charging four different battery banks. Based on our experience we can say with certainty it is a great combination. Here is some of what we have learn't.

The Juicy Bit

Let's get to the reason why having a wind turbine with solar is such a good combination before getting into the real waffle. When you rely on a battery system for your power needs whether its totally off grid or a kind of hybrid system, the bulk of your charging source will be solar. Using a properly sized solar system to charge your batteries is a must really. Where wind turbines add value is by supplementing that charging source because the sun does not always shine (especially at night). Sure the wind does not always blow but that is why you have batteries. The wind blows regardless of the time of day. At night is when your batteries are typically going to be used because, well, that's what they are for. Store the energy then use the energy.

A wind turbine will supply energy to your electrical system so long as the wind is blowing and for batteries the more you can do to reduce consumption from your batteries the longer they last. Batteries are the most expensive part of any system so understanding how they work and managing your energy use is part of the whole picture. Wind turbines therefore are an important part of this management strategy since they are cost effective and with our turbine tower easy to own now.

As for batteries and how they fit in this strategy, well we will do a separate just as boring blog about it.

The Waffly Bit

At Mannerfarm we use various battery types and charging sources in our home, shearing shed and cabin on our property. It has taken years of research, trial and error, hair pulling and skinned knuckles to find a good solution. One thing we certainly learned is that solar is by and far a well developed and understood means to charge a bunch of batteries. However the sun doesn't always shine (especially at night). So a need to find alternative means to charge our batteries became evident without burning liquid dinosaurs in a generator (plus we hate the noise).

This led us to start researching wind turbines, in particular what you can call micro wind turbines. These are wind turbines that sit in the range of 200 Watts to 600 Watts (you can get bigger and smaller ones but that's what we settled on). There was certainly a steep learning curve needed when our first one arrived. There are some things you can only truly learn through experience and observation. Just be careful once you get one turbine you might want more because one thing is for sure when the wind blows, they spin and that mechanical view of them generating power is very satisfying.

We have five wind turbines situated around our property and each is different in its behaviour, you could call it a personality of sorts.  Each turbine has specific properties that can be classified as output, noise, startup wind speed and what is called cut in wind speed. The output is pretty self-evident in its meaning, wind blows, turbine spins up and starts generating voltage and if it spins fast enough generates power (watts). The power generated is controlled by a charge controller. These can be built into the nacelle of the turbine or be in a separate controller. The controllers are pretty simple. Wind turbines generate three phase AC power. The controller converts this to DC and regulates the voltage so it doesn't over charge your batteries. The controller will "stall" the blades once your batteries reach a certain voltage (usually 14.4V for 12V systems). It will also "stall" the blades in an over-speed situation when wind gusts exceed around 50kmh.

The noise generated by a wind turbine is something we get asked a lot about. For sure they make some noise but again this is where our experimentation with various types has paid off. Blade design, bearings, balance and the electric motor itself all play a role in turbine noise. We have the whole range from completely silent through to a bit growly. None of the turbines are obnoxiously loud and the ones we sell with our towers are all tried and tested so check out our turbine offerings. The speed at which the turbine spins affects the noise it produces as the frequency changes with rotation speed. Some have a definite hum at lower speeds then rise in pitch as they speed up. Generally we find at lower rotational speeds they are louder than at higher speeds. The noise they generally make is a soft whooshing noise. If you live in a built up area check out our recommended silent turbine (stumpy). If you live in a more rural area then any of the others will be just fine. Personally we have never found the noise of our turbines intrusive or annoying. Its the sound of glorious watts being produced so how can't you be happy with that.

Each turbine type we have has a different startup wind speed. This is the wind speed at which the turbine starts rotating. This is determined by the turbine design and is dictated by things like blade design, bearings and electrical resistance on the motor. All of our turbines have very low wind speed startup and sometimes surprise even us when you would swear there is not even a breeze but they are turning over slowly. This is a good thing because it means they start producing power even if only a small amount at low wind speeds. This is beneficial because even if its only a few watts it is raising the voltage of the connected batteries.

So finally cut in wind speed is important with turbines. Voltage is like water pressure, to introduce positive water flow you must overcome the existing in-line water pressure. Once you do that water starts flowing from the source to the reservoir. Electricity is just like that. The turbine rotation has to produce a level of voltage that is greater than the connected battery voltage. Once that happens power is delivered into the battery. Technically though if you have load on that connected battery it will supplement what is being drawn from your battery. Only if the supply exceeds the load will the battery start charging. Hence cut in wind speed is the rotational speed of the turbine at which the turbine voltage exceeds the battery voltage and starts delivering power to your system.

So now lets get down to why we are here and reading this. You may wonder why you don't hear more about wind turbines as a charging source for batteries like solar. There are many reasons but the biggest issue isn't buying a turbine its mounting the sodding thing. It needs to go up on a pole and be mounted in such a way that its safe and can't come crashing down. The blades are sharp and they spin fast, real fast. Also at some stage you need to get it down and inspect it periodically from time to time to look for any damage or wear and tear. So things we have learned:

1. Do not mount a wind turbine on any building or structure (caravan, tiny home, shack etc...) unless you don't mind not sleeping. All turbines produce vibration at different rotational speeds and it is very difficult to isolate this vibration without a serious amount of expensive kit.

2. Turbines in strong gusty winds will flick about to turn into the wind. This can generate a fair amount of force on the structure and unless you have really built its mount properly it could tear itself off.

3. Raising and lowering your turbine for inspection and maintenance can be dangerous for you and the turbine unless you engineer in a mechanism to make this easier.

4. There are very few mounting kits available and all that do exist require a lot an engineering and certainly once built cannot be moved about easily, raised and lowered.

5. Mounting can be way more expensive than the turbine itself so economically its just not worth the hassle.

At Mannerfarm we really wanted the benefits of having a wind turbine coupled with Solar. So if the issue is only how to mount the turbines then that was just a problem to be solved. That's where our mobile/portable wind turbine towers have originated from. We designed and built a unique tower structure that is designed to be safe, secure and raised/lowered in minutes as well as easily packed up and moved to other locations. With a fully articulated tower supported by gas struts and stainless steel adjustable guide wires this tower can be placed in any location on any ground type. With self leveling bolt down feet so long as you have reasonable level ground you can level the tower using its adjustable feet and turnbuckles on the guide wires for the tower pole itself.

We designed and built the towers initially for our own use and they have worked extremely well. So well we now build them for anyone who wants one (for a fair price). You can be assured they are robust, safe and strong because if nothing else the storms that come off the Western Tiers across the dairy plains and slam into us have proven that.

One thing for sure is having a turbine tower you can easily transport means you can reposition it if you find that the site you chose for it is not optimal for catching the wind. We have certainly done that with ours. Obstruction from buildings, trees or just weird wind patterns has mean't we can experiment with the towers location. You certainly learn quickly how fickle wind can be with a turbine and its great fun and a challenge to find just the right spot.

So why not learn more about our towers and our options.

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