Most solar panels have no moving parts, so they make little if any sound. But your solar electrical power system includes more than the panels. The power inverter plays a key role and deserves attention as well.
Solar panel inverters sometimes make noise. There are a couple of possible explanations for the sound. If your solar energy generation system is designed and installed correctly, the sound should not be a major problem. If the volume is too loud there are steps you can take to fix the problem.
This article will tell you all about solar power inverters: why your solar electrical system needs a power inverter, and what to do about an inverter that is making too much noise.
What Is a Solar Panel Inverter?
Solar panels generate what is called “direct current” (DC). That means the electrical power flows steadily in one direction, from your battery’s negative terminal to the positive. Batteries work the same way. Most portable electronics, such as your cellular phone, use batteries and run on direct current.
All of the appliances in your home — anything that you would plug into an outlet anyway — operates on alternating current (AC). That means the flow of power reverses rapidly. In North America the power utilities provide current that cycles from positive to negative and back to positive 60 times every second.
This is why batteries have clearly marked positive and negative terminals, and battery-operated radios generally won’t work if you put the batteries in the wrong way. But if you look at the plug on many simple appliances, such as lamps, the metal prongs are the same. You can pull out the plug, turn it 180 degrees, and plug it back in and the appliance will still work. That’s because the power alternates, so it doesn’t matter very much which way the plug is inserted.
For any of the appliances in your home to use the power from your solar panels, something needs to convert it to alternating current that cycles 60 times a second. The inverter does this with solid-state switches that can turn direct current off and on in different directions hundreds or even thousands of times a second. (Here’s a more detailed explanation if you’re curious.)
Your inverter will also need to adjust voltage, so it’s at the standard of 120 volts. Depending on your setup, it will probably connect to the electric company’s power grid too. So your inverter will get your power “in synch” with the electricity from the grid, and will manage the flow of power back and forth between the grid, your home, and your solar panels. That device has a big job to do.
There are three typical inverter setups:
- String Inverters will string all your solar panels together and treat them as one big electrical current source. This works fine on most small solar panel rigs, especially if none of the panels is likely to be in the shade and all panels are producing energy at the same overall power level.
- String Inverters with Power Optimizers means individual solar panels will have small control units that standardize voltage, but there is still a central inverter unit that converts the direct current into alternating current.
- Microinverters are small inverters that are installed into every individual solar cell. The microinverters convert direct current into alternating current, then sends it along to the main circuit.
One significant advantage of both power optimizers and microinverters is that you can use them to monitor each solar cell’s performance and adjust if one cell is not performing as well as the rest. The larger your solar array, the more that will matter. But no matter which rig you install, direct current needs to be changed into alternating current. Inverters are every bit as necessary as solar cells.
Your solar cells have no moving parts and do not need to be cooled, so there is no need for a fan. If the rigging is loose or heat causes the mounts to expand and contract you may hear some scratching or creaking noises. Wind may blow between your roof and the solar panels. Otherwise the panels themselves should be whisper quiet.
Why Your Solar Inverter Is Making Noise
The inverter is different. While the switches that convert direct current to alternating current are solid state and have no moving parts, the switching process itself can still create a lot of heat, so your inverter will likely have a fan. In addition, your inverter will be handling a lot of power, and that by itself can create a low humming sound, like you hear around high-power electric lines or power transformers.
Usually the sound is not a significant problem, but a poorly-installed inverter can make it one. Ideally the inverter should be in a relatively cool place, out of the sun but well-ventilated, and not in a place where people congregate.
Solar Inverter High-Pitched Noise: How to Fix
This constant, high-pitched whine is the sort of sound you definitely do not want to hear from your inverter. There are several reasons why your inverter might be making loud noises. You may want to have a technician examine the inverter and make recommendations. But the most common explanations are that the inverter is either worn out or overworked.
A poorly chosen or installed inverter can wear out in as little as 3 1/2 to 4 years. The switches at the heart of the inverter might be solid-state with no moving parts, but they still need to be cooled, and the fan motor can break down quickly with heavy use — making a loud racket as it does. And even if the inverter isn’t ready to conk out, heavy use means the fan will constantly be running, making sound as it does.
If the sound is distracting but your inverter can handle the load, you might consider moving the inverter further away from your home, or to a place where it is further away from bedrooms and living areas of your house. Not every sound from your inverter is cause for alarm. Just make sure you pick a spot that is out of the sun and allows air to circulate around the unit.
If your inverter does need to be replaced, you might want to upgrade to a model that can handle more current than the old one. A more powerful unit can handle the current demands with less strain. The switches will give off less heat, and the cooling fan will not need to run as often. This means your inverter will be quieter and last longer.
A good solar inverter is an essential part of any solar electrical power generation system. Without the inverter, your home cannot use the electricity from your solar panels; they need alternating current and your solar panels produce direct current. The inverter is the part that makes the switch. Depending on your setup, it probably also manages your home’s connection to the larger electrical grid.
There’s a lot of power flowing through your inverter, and the equipment inside does a lot of work. The electronics and the fans that cool them can be noisy at times. So it’s crucial that you pick the right spot for your inverter, one where it operates efficiently without distracting you and your family. Just as important, you want to be sure you have an inverter that can handle the load.
A good inverter, installed the right way, will ensure that you get the most out of your solar panels and make your home more peaceful.