Beginners Guide to Wind Turbine Charge Controllers | Off Grid Permaculture
Wind Turbine Charge Controller

Beginners Guide to Wind Turbine Charge Controllers

Daniel Mark Schwartz Profile Picture

When I first started learning about using wind turbines to generate off grid energy, I thought that a solar charge controller and wind turbine charge controller might be the same thing. However, now I know that mixing up the two can be a huge expensive mistake. That’s why I decided to write this short article explaining exactly what a wind power charge controller does, and how to choose the right one for your system.

A wind charge controller is an electronic device that both ensures that your turbines don’t over charge your batteries, as well as limit how fast speed the wind turbine blades are able to spin when the batteries are full or in high wind situations. Having a purpose designed solar charge controller is essential to safely running an wind turbine, unless the wind turbine has a built in safety system.

Choosing the right charge controller for your system is absolutely essential for safe and efficient functioning of your off grid energy system. In the following section I’ll answer the most common questions and get you started quickly with your solar system.

How to Choose A Wind Turbine Charge Controller for Your Off Grid System

When choosing a wind power charge controller, is absolutely essential that you choose a controller that is matched to your system in terms of maximum size and capability. Here is a short list of exactly what you need to compare —

  • Input power type (three phase AC vs two phase AC vs DC)
  • Maximum power capability in watts (must meet or exceed your wind turbine’s capability)
  • Supports your battery bank type (sealed, flooded, lithium, etc)
  • Supports your battery bank voltage (12V, 24V, etc)

If a wind charge controller meets this specification, then it is suitable for use with your wind turbine. Some wind turbines already come with their own charge controller either built in or included in the box, which you have the option of replacing later on if necessary.

Many people ask me what wind turbine charge controller I would recommend. I honestly think the best place to get started is with the PIKASOLA Wind Turbine Charge Controller.

This amazingly inexpensive little unit supports 3 three phase AC input of up to 600 watts. Because it is water proof, and has an integrated dump load (see below for an explanation of what a dump load is), making this unit extremely easy to install and use.

This is my preferred unit if you plan on adding wind to an existing solar system, or you want to build a wind system with multiple turbines attached to one battery bank. Check the above Amazon link for current pricing.

How to Mix Solar Power and Wind Power on the Same System

Mixing solar and wind power can be accomplished in two ways —

  • Attach multiple charge controllers to the same battery bank
  • Buy a purpose build dual purpose wind solar charge controller

If you are not experienced with off grid electrical systems, by far the least complicated and most reliable way to go is the second method, buying a dedicated dual purpose charge controller.

There are not many good examples of this feature set on the market, but Missouri Wind and Solar has by far the best option available in their SkyMax 440 Wind Solar Hydro Charge Controller.

This unit absolutely beats the pants of all every other unit that I have seen in terms of build quality and capability. Pretty much everything else on eBay and Amazon, as well as third party seller, are just cheap Chinese imports. For a dependable unit, I would definitely spring for one of these amazing lifetime units.

How to Have Multiple Wind Turbines on Single Off Grid Power System

Unfortunately, there is no good way to have multiple wind turbines attached to the same charge controller, especially if they are three phase AC wind turbines, which is by far the most common. Mixing AC power takes special care, otherwise you run the risk of the AC alternators/generators working against each other instead of proving additional power.

If you are going to hook up more than one turbine to a single battery bank, then you will need a separate charge charge controller for each. This will ensure each turbine is run safely, avoiding over speed conditions. And, since the charge controllers handle AC to DC conversion internally, you can just connect each charge controller in parallel to the battery bank.

In this way, you can incrementally add additional wind turbines to your off grid energy system whenever you like.

For systems with multiple wind turbines, or if you are adding another turbine on to an existing system, then I again recommend the PIKASOLA Wind Turbine Charge Controller.

Additionally, when using multiple different charge controllers on a single battery bank, it is important to make sure they have identical charge profiles, or you risk one part system (wind turbine, solar panels, or water turbine) shutting of before the others and not fully charging the batteries.

When adding several wind charge controllers together, the easy way to do this is to just use identical charge controllers for each turbine.

If you are mixing wind and solar charge controllers, then you will need to check the settings of each controller, and make sure they match. Usually, mid to high end solar charge controllers have the ability to manually set the battery charge profile voltages, so I would recommend setting those to match those of your wind charge controller(s).

How to Use a Solar (MPPT or PWM) Charge Controller For a Wind Turbine

Sometimes people want to know if they can use their solar charge controller as a wind charge controller. While it is possible, it isn’t always easy, or the best idea.

First of all, I don’t recommend using an MPPT solar charge controller as awind charge controller, because the maximum power point tracking features often don’t play nice with the wind turbine, lowering the performance. For more info on the difference between MPPT and PWM charge controllers check out my article below —

Below I will describe how to add these features to your PWM charge controller, but this is a fairly advanced project.

Adding An External Breaking Wind Turbine Breaking Dump Load

Unlike solar panels, which should be disconnected when not in use, wind turbines (and water turbines as well) must be connected to dump load when not in use or in high wind situations. See below for a explanation on why this is necessary.

While it is possible to run a wind turbine, and get power from it, without a dump load, it is not safe or recommended.

Adding a dump load to your PWM can be added to your system using a 12V or 24V double pole double throw (DPDT) relay and an external solar dump load (or other suitable resistive load) —

To wire this up, you would connect the dump load to the normally open terminals, the charge controller to the normally closed terminals, and the wind turbine (after rectification to DC if applicable) to both the common terminals and across the coil terminals.

The idea here is that in normal operation, the wind turbine will connect directly to the charge controller, like normal. However, when the turbine goes fast enough to raise the voltage above the relay trip potential, it will switch the turbine directly over to the load, slowing it down.

Depending on your turbine output voltage and your relay trip voltage, you may need to insert a resistor divider network on one of the coil terminals to adjust the trip voltage.

This system is not as good as a real wind turbine charge controller (like the ones I recommend using above), because it will not partially divert excesses power and will only reconnect the load one the wind has died down. This has the potential to waste power or not fully charge your battery bank. However, it is much safer than having no dump load at all.

Building an AC to DC Rectifier For a Wind Turbine

If you have a DC wind turbine, perhaps a DIY one built on a DC alternator / generator, then you don’t need to worry about conversion.

However, if you have a three phase AC alternator (most common for commercial wind turbines), or a single phase AC alternator (common for home build turbines from re-purposed permanent magnet motors or common AC alternators), then you will need to first rectify the AC voltage in to DC before applying it to the PWM charge controller.

To do this you will need a three phase rectifier or a bridge rectifier (for single phase AC). Choose a component that exceeds your the maximum possible rating of your wind turbine in both maximum voltage and maximum current. There is no harm in over specifying your rectifier.

It is also best attach a large capacitor in the neighborhood of 2200 uF that exceeds the voltage rating of your wind turbine as well. This component will smooth out the rectified voltage and avoid any confusion on the part of the PWM charge controller, which is designed to operate on fairly steady DC voltages produced by solar panels.

Be very careful when working with large capacitors, as they can be dangerous or deadly if mishandled. Electrolytic capacitors can vent hot gas or explode if connected backwards. Also, charged capacitors are capable of delivering deadly shocks. Only attempt this project if you are knowledgeable about electronics, or have some knowledgeable to assist you.

What Is A Dump Load In A Wind Power System and Why Is It Needed?

A wind turbine dump load is an essential safety feature for wind (and water) turbines. For more info on micro hydro water turbines and controllers, see —

Turbines require an electrical load to keep them from spinning too fast. Completely disconnected alternators / generators will spin freely, allowing strong winds to spin them dangerously fast. Potentially causing the destruction of the turbine and posing a safety risk to anyone in the vicinity.

Wind turbine change controllers prevent this problem by routing any excess power to a dump load or dump resistor, and never allowing the wind turbine to spin freely. Dump loads simply turn the excess power in to heat, and serve as an electrical breaking system for your wind generator.

What is a charge controller for wind turbine?

Wind turbines require special charge controllers that not only prevent battery over charging but also divert excess energy to a dump load to prevent the turbine from spinning too fast, causing damage. Wind turbine charge controllers also usually convert AC current to DC current, which is necessary for AC wind turbines, which are very common.

Can I use a solar charge controller for a wind turbine?

No. While it is possible to get power from a wind turbine in some cases using a solar charge controller, they do not have appropriate safety features (eg over speed breaking circuits) to use with most wind turbines. Always use an appropriately rated wind charge controller or mixed wind solar charge controller with wind turbines.

What does a wind turbine controller do?

A wind turbine controller protects your battery bank from over charging, applies breaking loads to limit wind turbine over speeds due to high winds or light loading, and most often convert AC power generated by wind turbine 3-phase alternators to DC power used by all battery banks.