Solar charge controllers are not compatible with wind turbines, despite the fact that both energy sources employ the same kind of controllers, PWM and MPPT.
The charge controller for a wind turbine must allow the turbine to dump its load and so protect both the battery and the turbine, but the charge controller for a solar panel only needs to remove the charge from the battery after it reaches its capacity.
Is it possible to use a solar charge controller with a wind turbine?
Wind turbines require sophisticated charge controllers that avoid battery overcharging while also diverting excess energy to a dump load to keep the rotor from spinning too quickly and risking damage. Charge controllers for wind turbines typically convert AC current to DC current, which is required for AC wind turbines, which are relatively frequent.
Can I use a solar charge controller for a wind turbine?
No. While a solar charge controller can be used to get power from a wind turbine in some situations, they lack the necessary safety features (such as overspeed breaking circuits) to be used with most wind turbines. With wind turbines, always use a properly rated wind charge controller or a mixed wind solar charge controller.
What does a wind turbine controller do?
A wind turbine controller prevents overcharging of your battery bank, applies breaking loads to restrict wind turbine overspeeds caused by high winds or low loading, and converts AC power generated by wind turbine 3-phase alternators to DC power used by all battery banks.
Is it possible to link my solar system to a wind turbine?
Wind generators will generate power on a continuous basis, which means you’ll need a place to discharge the excess energy. If you want to use a wind generator, you should get one of the controllers built expressly for this reason. This will enable you to use the excess energy generated by the wind turbine system to power a water heater or other equipment. Using one of these controllers solves a possible problem while also increasing efficiency because the extra energy can always be put to good use.
The same wiring technique can be used to connect wind generators and solar panels. All you have to do now is conduct some research and get a controller that can handle both systems. The setup is quite simple and will vary slightly depending on the specific energy systems you’re using. Many people who utilise these systems try to rig the wiring on their own, which is usually a bad idea. When working with such a large amount of energy, a lot may go wrong, and you could easily damage yourself or cause a fire. Rather than dealing with these potential dangers, hiring a professional to put the system together for you is a prudent alternative. Another advantage of going this method is that you may have the business examine your system and offer a controller that can handle both solar panels and wind generators.
Some people believe that they require separate wiring for each energy system they use. This is far from the case, and it is incredibly inefficient when you consider how simple it is to merge the wiring. All you’ll need is a controller that can manage both of them at the same time. These controllers are also reasonably priced, so there’s no necessity to set up two distinct wiring systems.
Call a professional to inspect your solar panels and wind generators if you want to make the process much simpler on yourself and avoid a potential disaster. They’ll have the knowledge to properly examine your system and should also have the essential parts on hand to do the task. Many people live off the grid as well. If you’re in this circumstance and don’t have access to a specialist, do your homework and take all essential safety steps.
Is it possible to charge a battery with a wind turbine?
We frequently receive inquiries regarding why dump loads are required on wind turbines and how to determine the proper dump load(s) for a given system. The first section of this article will discuss why dump loads are utilised on wind turbines, and the second section will go over how to figure out which dump loads will work best for your system.
First and foremost, please notice that the terms “diversion load” and “dump load” are synonymous.
Why is a dump or diversion load necessary?
When running, wind turbines are meant to be loaded. The load on a wind turbine is nearly always an electrical load that draws power from the turbine’s generator. A battery bank and an electrical grid are the two most typical loads for a wind turbine. Although many of you reading this post are probably aware of this, it is critical to realise that an electrical load (such as a battery bank or the electric grid) keeps a wind turbine within its designated operating range.
Let’s use a hand drill on a piece of wood as an example to truly drive this concept home. The hand drill represents a wind turbine, and the wood represents an electrical load in our comparison. If you put the hand drill to its greatest power level and let it spin in the open air, it will probably spin at around 700 rpm. Because the drill isn’t doing any work, this is known as a “no load” condition. What will happen if we use the hand drill’s highest power setting to begin drilling a hole in the wood? When compared to spinning in free air, the hand drill’s rpm will definitely slow down significantly. This is due to the fact that the drill now has to work extra hard to bore a hole in the wood. This is what is referred to as a “laden circumstance.” A drill is now built to run with no load, while a wind turbine isn’t.
In high wind conditions, a wind turbine that is not loaded can self-destruct. Wind turbine blades can spin so fast under strong winds with no load that they can rip off or, at the at least, exert extreme pressures and strains on the wind turbine components, causing them to wear out quickly. In other words, when a wind turbine is loaded, it runs safely and properly.
Wind turbines are typically utilised to charge battery banks or feed an electrical system, as previously indicated. Both of these applications required dump loads, but let’s take a closer look at the battery bank application.
A wind turbine will keep charging a battery bank until the bank is completely charged. This is around 14 volts for a 12 volt battery bank (The exact fully charged voltage of a 12 volt battery bank depends on the type of batteries being used). Once the battery bank is fully charged, the wind turbine must stop charging it since overcharging batteries is dangerous for a variety of reasons (i.e. battery destruction, risk of explosion, etc.) But wait, there’s a snag! We must maintain an electrical load on the wind turbine! A diversion load charge controller is utilised to perform this purpose.
A diversion load charge controller is essentially a voltage sensor switch. The voltage of the battery bank is constantly monitored by the charge controller. When the voltage level in a 12 volt battery bank hits around 14 volts, the charge controller detects this and disconnects the wind turbine from the battery bank. A voltage sensor switch is a diversion load charge controller, as we previously stated. So, in addition to disconnecting the wind turbine from the battery bank, a diversion load charge controller can also switch the wind turbine’s connection to the diversion load! And the diversion load charge controller performs exactly that, keeping the wind turbine at a steady electrical load.
The charge controller detects a slight reduction in battery bank voltage (about 13.6 volts for a 12 volt battery bank) and turns the wind turbine back to charging the battery bank. This cycle is repeated as needed to prevent the battery bank from overcharging and to keep the wind turbine running.
How do I figure out how many dump loads I need?
Now, in order to determine the proper size of your dump load system, you must first ask yourself the following questions: (1)What is my system’s voltage (12 volt battery bank, 48 volt battery bank, 200 volts?) (2) At full power, how many amps will your wind turbine produce? You can continue on to the next phase after you have this information.
We’ll need to do some math and apply Ohm’s Law in the next few phases. Let’s use a real-life example instead of generalisations. Our Windtura 500 wind turbine will be used to charge a 24 volt battery bank in this demonstration.
26 amps is the answer. (We can see this from the Windtura 500’s reported power curve.)
Step 3: The dump load mechanism must be capable of dumping the wind turbine’s maximum output power. Power equals Volts x Amps, according to Ohm’s law. The voltage of the system is the voltage of the battery bank (We are going to use 29 volts which is roughly the voltage of a fully charged 24 volt battery bank). The current produced by the Windtura 500 at maximum power is measured in amps (26 amps).
Step 4: We’ll need a dump load capable of discharging at least 754 Watts. In this example, we’ll use our 24 volt dump load resistors. The internal resistance of these resistors is 2.9 ohms. We need to determine out how much electricity this resistor will consume, knowing that it is 2.9 ohms.
Step 5: Work out how much power a 2.9 ohm resistor uses:
Using Ohm’s law, Voltage = Current x Resistance, and some basic algebra, we get the following equation:
(Battery bank voltage)/(Resistor’s resistance) = (29 volts)/(2.9 Ohms) = 10 amps Current = (Voltage)/(Resistance) = (Battery bank voltage)/(Resistor’s resistance) = (Battery bank voltage)/(Resistor’s resistance)
Now we know that one of these resistors will draw 10 amps of electricity at 29 volts (battery bank voltage). What is the power consumption of the resistor?
We all know how simple it is:
(Battery bank voltage) x (amps through resistor) = (29 volts) x (10 amps) = 290 Watts Power = Volt x Amps = (Battery bank voltage) x (amps through resistor) = (29 volts) x (10 amps) = 290 Watts
As a result, one of our WindyNation 24 volt dump load resistors will be able to handle 290 Watts. Important: Make sure the dump load you’re using is rated to withstand 290 Watts at continuous duty at this point, or there could be a serious fire hazard. The WindyNation 24 volt dump loads can carry up to 320 Watts of continuous power, thus they’ll be perfect for this job.
Step 6: Connecting a 290-watt dump load resistor to a 754-watt load:
If you read Step 3 again, you’ll see that our dump load system must be capable of dumping at least 754 Watts. What can we do with a 290 Watt dump load resistor to accomplish this? That’s a piece of cake! The dump load Wattage is cumulative if numerous 290 Watt dump load resistors are wired in parallel. As a result, we have the following simple equation:
Total Watts required for our dump load system = (290 Watts) x (number of 2.9 Ohm resistors required in parallel)
Also, solve the following problems using simple algebra:
We can’t utilise 2.6 resistors because our resistors only come in whole units. We must round up because we require AT LEAST 754 Watts. As a result, we’ll need to connect three WindyNation 2.9 Ohm resistors in series. This gives us a dump load capacity of 870 Watts. We’ve now put up a dump load system that’s appropriate for the wind turbine and battery bank we’re using in this scenario. Any wind turbine system can benefit from the same conceptual process (Steps 1-6).
We hope that this post has shown why dump loads are required for wind turbines and how to determine how to set one up for your specific system.
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What is an MPPT solar controller, and how does it work?
The theory and functioning of “Maximum Power Point Tracking” as employed in solar electric charge controllers are covered in this section.
A maximum power point tracker, or MPPT, is an electronic DC to DC converter that optimises the match between the solar array (PV panels) and the battery bank or utility grid. Simply put, they convert the higher voltage DC output from solar panels (as well as a few wind generators) to the lower voltage required to charge batteries.
(These are sometimes referred to as “power point trackers,” not to be confused with PANEL trackers, which are solar panel mounts that follow or track the sun.)
So what do you mean by “optimize”?
Solar cells are fascinating devices. They are, however, not particularly intelligent. Batteries aren’t either; in fact, they’re downright stupid. The majority of PV panels are designed to produce 12 volts nominally. The catch is the word “nominal.” In reality, nearly all “12-volt” solar panels are designed to produce between 16 and 18 volts. The issue is that a nominal 12-volt battery is near to an actual 12-volt battery – 10.5 to 12.7 volts, depending on charge condition. Most batteries require between 13.2 and 14.4 volts to completely charge, which is very different from what most panels are designed to produce.
So, now we’ve got this cool 130-watt solar panel. The first snag is that it’s only rated for 130 watts at a specific voltage and current. 7.39 amps at 17.6 volts are rated for the Kyocera KC-130. 7.39 amps multiplied by 17.6 volts equals 130 watts.
Now the Catch 22
So, what happens if you use a conventional charge controller to connect this 130-watt panel to your battery?
Your panel is capable of delivering 7.4 amps. Your battery is charged to 12 volts: 7.4 amps multiplied by 12 volts equals 88.8 watts. You saved over 41 watts, but you had to pay for 130. That 41 watts isn’t going anywhere; it’s just not being created because the panel and battery aren’t a good match. It’s even worse if you have a really low battery, like 10.5 volts, because you may be losing up to 35 percent of your power (11 volts x 7.4 amps = 81.4 watts). You lost approximately 48 watts.
One alternative you might consider is to design panels that output 14 volts or less to match the battery.
The panel is rated at 130 watts in full sunshine at a specific temperature, which is catch #22a (STC – or standard test conditions). You won’t receive 17.4 volts if the solar panel’s temperature is too high. You might get under 16 volts at the temperatures encountered in many hot climate places. You’re in danger if you started with a 15-volt panel (like some of the so-called “self-regulating” panels), because there won’t be enough voltage to charge the battery. Solar panels must be designed with enough wiggle room to work in the most adverse conditions. The panel will just sit there looking silly, and your batteries will become even more stupid.
What is Maximum Power Point Tracking?
The term “tracking” is a bit of a misnomer:
Panel tracking occurs when the panels are mounted on a mount that moves with the sun. The Zomeworks are the most common. These maximise output by following the sun as it moves across the sky. These normally provide a 15% increase in the winter and up to a 35% increase in the summer.
For MPPT controllers, this is the polar opposite of seasonal variation. Because the temperature of the panels is lower in the winter, they produce more power. Due to the shorter days, winter is usually when you require the most power from your solar panels.
Maximum Power Point Tracking is a type of electronic tracking that is commonly done with a computer. The charge controller compares the output of the panels to the voltage of the battery. It then determines what the best power output from the panel is for charging the battery. It converts this to the best voltage possible in order to get the most AMPS into the battery. (Keep in mind that the number of Amps into the battery is what matters.) The conversion efficiency of most current MPPTs is around 93-97 percent. In the winter, you can expect a 20 to 45 percent increase in power, whereas in the summer, you can expect a 10-15 percent increase. The amount of gain varies greatly based on the weather, temperature, battery state of charge, and other variables.
As the cost of solar reduces and utility prices rise, grid connection solutions are becoming increasingly popular. There are a variety of grid-tie only (no battery) inverter brands available. MPPT is incorporated into each of these. The MPPT conversion efficiency on those is from 94 percent to 97 percent.
How Maximum Power Point Tracking works
This is where optimisation, also known as maximum power point tracking, comes into play. Assume your battery is at 12 volts and is low. An MPPT converts 17.6 volts at 7.4 amps to 10.8 amps at 12 volts, which is what the battery now receives. Everyone is thrilled since you still have almost 130 watts.
At 11.5 volts, you should receive roughly 11.3 amps for 100 percent power conversion, but you’ll need to give the battery a higher voltage to force the amps in. And this is a simplified description; in reality, the MPPT charge controller’s output may vary continuously to ensure that the maximum amps are delivered to the battery.
A screenshot from the Maui Solar Software “PV-Design Pro” computer programme is seen on the left (click on the picture for full-size image). When you look at the green line, you’ll notice a dramatic peak in the upper right corner, which symbolises the maximum power point. An MPPT controller “looks” for that precise point, then performs the voltage/current conversion to match the battery’s requirements. In real life, that peak shifts with the changing light and weather.
In almost all cases, an MPPT tracks the maximum power point, which will differ from the STC (Standard Test Conditions) rating. Because the power output increases higher as the panel temperature goes down, a 120-watt panel can actually put out over 130+ watts in very cold conditions – but if you don’t have some way of measuring that power point, you’ll lose it. In extreme heat, on the other hand, the power lowers – you lose power as the temperature rises. As a result, you gain less in the summer.
Under the following circumstances, MPPTs are most effective:
- Cold weather solar panels perform better in cold weather, but without an MPPT, you’ll lose the majority of the benefits. Cold weather is most likely in the winter, when daylight hours are at their lowest and you need the greatest power to recharge your batteries.
- Low battery charge – the lower the level of charge in your battery, the more current it receives from an MPPT – another time when the extra power is most needed. Both of these situations can exist at the same moment.
- Long wire runs – If your panels are 100 feet apart and you’re charging a 12-volt battery, the voltage drop and power loss can be significant unless you utilise extremely wide wire. This can be quite costly. The power loss is substantially lower if four 12 volt panels are put in series for 48 volts, and the controller will convert the high voltage to 12 volts at the battery. This also means that if the controller is fed by a high-voltage panel, you can use much smaller cable.
How a Maximum Power Point Tracker Works:
The Power Point Tracker is a DC to DC converter with a high frequency. To precisely match the panels to the batteries, they take the DC input from the solar panels, convert it to high-frequency AC, and then convert it back to a different DC voltage and current. MPPTs work at very high audio frequencies, usually between 20 and 80 kHz. High-frequency circuits have the advantage of being able to be created using very high-efficiency transformers and compact components. High-frequency circuit design can be difficult due to issues with components of the circuit “broadcasting” like a radio transmitter, producing radio and television interference. Isolation and suppression of noise become critical.
There are a few non-digital (linear) MPPT charge controls on the market. These are far easier and less expensive to construct and design than computerised ones. They do boost efficiency to some extent, but total efficiency varies greatly – and we’ve seen a few lose their “tracking point” and even deteriorate. If a cloud passes over the panel, the linear circuit will look for the next best location, but it will be too far out in the deep end to find it when the sun returns. Thankfully, there aren’t many of these left.
The power point tracker (and all DC to DC converters) work by taking the DC input current, converting it to AC, passing it through a transformer (typically a toroid, which looks like a doughnut), and then rectifying it back to DC before the output regulator. In most DC to DC converters, this is purely an electrical process with no real intelligence involved save for some output voltage management. Solar charge controllers require a lot more intelligence because light and temperature conditions change throughout the day, as well as battery voltage fluctuations.