Building a wind turbine generator system can be a truly rewarding project. Not only does a wind turbine provide you with a free source of renewable energy, but designing the system itself is a fun process. However, many people wonder how much power a wind turbine can actually produce. The answer is not as straightforward as a simple number.
The complexity stems from the fact that a wind turbine cannot typically power a device directly. The power from a wind turbine is unregulated and inconsistent, meaning that you cannot simply plug an appliance into it and expect it to function properly. To provide reliable power, the energy created by the turbine must be regulated, stored in a battery system, and then used by your devices. Thus, the amount of equipment that your wind energy system can power is largely determined by the weakest link in the chain. Even the largest turbine will be severely hampered by a battery bank that is too small.
Similarly, an expansive system of batteries will quickly become unusable if the turbine feeding them is too small. Thus, it is important to look at the entire system to answer the question “How much energy does a wind turbine produce?”
How is Power Measured
When looking at the components of an off-grid power system, don’t worry about getting too bogged down in technical details. Really, there are only two terms you need to know. The first is “watts.” A watt is a unit of measurement that describes how much energy is being used or produced by a device. Think of this like a garden hose. A small wind turbine may produce about 100-watts of energy on a blustery day, whereas a larger unit may produce upwards of 1,000-watts. The larger the source, the more water can spray through the hose.
The other term you need to understand is the related “watt-hour.” A watt-hour is a unit that expresses how much energy a battery can hold. If the power source is the hose spraying the water, the battery is the bucket catching the water. The numbers are fairly intuitive, luckily. A 100-watt power source can charge a 100-watt-hour battery in one hour. Or, a 500 watt-hour battery can power a 250-watt device for 2 hours. Simple enough, right?
Sometimes you will see the term “amp-hours”, but never fear. Simply multiply that number by the voltage of the battery (often 12) and you will arrive at the watt-hour rating.
The Basics of a Wind Turbine System
As I mentioned above, the wind turbine itself is just the starting point of a large off-grid energy system. Although the wind turbine will feed energy into the system, there are a few other components needed before you can start using the system to its fullest capacity. For a more in-depth overview, consider taking a look at our article on “How Much Power Can a Solar Panel Generate?”
However, here are the basics of what you’ll need.
A Wind Turbine
Of course, the most salient component in a wind turbine system is the turbine itself. The cost, design, and capacity of a home turbine varies as much as any given budget and imagination. On the smaller end of the scale, budget-oriented wind turbines can be had for as little as $100. At this price point, you shouldn’t be expecting commercial quality or a standalone source that will power your entire mansion. However, you will be able to find a solution that can adequately produce about 100-watts of power with reasonable quality. Even high-end models are not excessively costly, though. Many commercial-grade units capable of producing over 1,000-watts of power can be had for under $500.
Beyond the various price points, there are several different styles of turbines. The most traditional style is a “propellor” model, which has vertical blades. When you think of a windmill, this is likely what you’re thinking of. While these models can be very efficient, they work less effectively when the wind changes direction often. If you live in an area that has turbulent winds, consider a “lantern” style turbine. Lantern style models have blades that spin around a central horizontal axis. Thus, they are indifferent to where the wind is blowing.
The last consideration is the blade size. Every wind turbine has a minimum and maximum speed at which it can produce power. Larger blades can produce energy at lower wind speeds but become unstable at higher speeds. Smaller blades can spin faster in gale-force winds but take more wind-speed to get moving. Thus, it is important to do some research to find the turbine that suits your needs – and your environment – the best. The better you tailor your turbine, the more power it will produce.
The Charge Controller
The power from a wind generator is as variable as the speed of the wind itself. Thus, a wind turbine cannot charge a battery directly. Instead, it must go through a device known intuitively as a charge controller. A charge controller is a fairly simple circuit that takes the unregulated power of the turbine and converts it into a consistent signal that can be used to charge a battery bank. Sometimes a turbine kit will include a charge controller, but you will often have to purchase one separately.
It is important to find a charge controller that has a higher capacity than your turbine. For example, if you have a 1,000-watt turbine but a 500-watt charge controller, you will bottle-neck your system and hamper the maximum output. Even worse, overloading a small charge controller can damage the unit or even cause a fire. Simply put, always get a larger controller than you need. Many models also support a solar input, allowing you to have two sources of power keeping your battery bank topped off.
A Battery Bank
Because the power from a turbine is not always consistent, and because the weather is not always windy, you will need a way to store the power produced by your turbine. The battery bank will likely be the single largest contributing factor in determining how much your off-grid system can power.
Battery technology is an extremely complex and ever-changing field, so it would be impossible to cover all of the nuances in this context. Yet, regardless of whether you opt for a lead-acid, AGM, lithium iron phosphate, or lithium-ion battery system, you will still be able to measure the capacity of your system in watt-hours. The number of watt-hours that your battery bank is capable of storing will be the determining factor in how much power you can draw off your system before it becomes fully depleted. Let’s look at an example.
Perhaps the simplest battery bank would be a single car battery. These are typically lead-acid or AGM, but again, the specific formulation is not particularly important. A single car battery is typically around 500 watt-hours. Thus, a moderately sized wind turbine will be able to charge such a battery fully in around an hour. Similarly, such a battery bank would be able to power a 50-watt device (like a laptop) for around 10-hours. A battery bank can be as large or as small as you choose to make it. While this will likely be the most significant investment you make towards your system, it will also be the decision that makes the biggest impact on how much power your system will reliably produce.
The inverter is the last link in the chain from the wind blowing to your devices getting power. Batteries typically store energy using low-voltage direct-current power. However, most household devices use 120-volt alternating-current power. The inverter is the device that converts this battery power into the A/C power that your household devices need.
Inverters are measured in watts, which signifies how much power they can produce at once. Thus, even if you have the largest turbine, charge controller, and battery bank in the world, you will only be able to draw as much power as your inverter can sustain. Depending on the devices you expect to power, you may not actually need that large of an inverter. A 1,000-watt inverter is a fairly common size, and this can power almost everything you would need except perhaps an air conditioner, a space heater, or an electric hot plate.
Of course, inverters come in all shapes and sizes. If you need to run larger equipment, you can certainly get an inverter that is capable of the task. However, you must make sure your turbine and battery bank can support it. For example, if you have a 5,000-watt inverter but only a 1,000 watt-hour battery bank, your system will be lights out in only 12 minutes.
The Rating of a Turbine Isn’t Necessarily the Output
Although manufacturers are not generally trying to be intentionally misleading, the rated output of a wind turbine can be somewhat confusing. When dealing with a wind turbine, the rated output is the maximum amount of power that the unit can produce. This is a very different circumstance than a traditional gas generator, wherein you turn it on and it can immediately produce the full rated power.
In most cases, a wind turbine must be exposed to winds over 60 miles/hour before it produces its maximum output. Even the most storm-prone regions will not regularly get winds of this strength. Thus, you need to temper your expectations. If you live in an area where the wind is typically only 10-15 miles/hour, your turbine may only be able to produce about 25% of its rated output. Similarly, 30 miles/hour may only net you 50%. While the relationship is not necessarily linear, it is important to realize that you are unlikely to routinely see the maximum rated output of your turbine, and you should design your system accordingly.
A Brief Look at Power Consumptions
You are likely reading this article to get a definitive answer regarding whether or not a wind turbine system can power a specific device. As you can see, the answer is, unfortunately, more complicated. The amount that your system can power will depend on several factors including your wind speeds and the specific components you choose. However, it is still helpful to consider a “typical” system, and look at what devices it could reliably power.
Most home turbines will be rated for around 500-watts of power. Thus, in normal conditions, you might expect this turbine to produce about 200-watts of energy for most of the day. With a moderate two-battery bank of around 1,000 watt-hours, such a turbine should not have an issue keeping those batteries charged during normal conditions. To determine if this system could power the devices you typically use, you simply need to add up the individual draws of each device. Google is your friend here, and a quick search for “device power consumption chart” will yield you a wealth of information. However, here are some typical consumption rates for common devices:
- LED Lights: 5-Watts
- Cell Phone: 5-Watts
- Laptop: 65-Watts
- 24” LCD TV: 60-Watts
- Box Fan: 80-Watts
- Window Air Conditioner: 1,000-watts
- Single-Burner Electric Hotplate: 1,800-watts
As you can see, the consumption of devices can vary broadly, so doing the math ahead of time can save you a lot of headaches.
Wind turbines are an incredible source of sustainable power, provided that you have a well-designed system and reasonable expectations. But how much power does a wind turbine generate? While a small home wind turbine won’t be able to power an entire town, you may be surprised to learn how powerful these seemingly simple devices can be. Just as with every system you encounter, an off-grid system is only as strong as its weakest link.
Thus, spending some time to determine your specific needs to source the right equipment can go a long way. Luckily, the execution is simple once you know the basics.