In this video
- An inverter is simply a device that converts DC power (from solar panels or batteries) into the AC sine-wave power your home runs on.
- Most modern mini-splits use inverter compressors, which rectify AC to DC internally so a variable-speed, 3-phase motor can ramp up and down instead of switching on and off.
- Inverter compressors avoid the high inrush current of old on/off units, which makes them roughly 30% more efficient, longer-lasting, and more comfortable to live with.
- A solar hybrid mini-split skips that extra rectification step by running directly on the DC power already coming off your solar panels.
- At night or on cloudy days, a solar hybrid mini-split blends grid AC power in with solar DC power, so the unit still runs efficiently without needing a battery bank.
Questions this video answers
Does inverter AC mean it runs on solar?
No. An inverter air conditioner just uses a variable-speed inverter compressor to run more efficiently on regular AC grid power. It has nothing to do with solar unless it's specifically built as a solar hybrid mini-split.
What is the difference between an inverter and an inverter compressor?
An inverter is a general term for any device that converts DC power into AC power, like the inverter in a solar or battery system. An inverter compressor is the specific variable-speed motor inside a mini-split that rectifies AC to DC and back so it can ramp its speed up and down instead of just turning fully on or off.
Can you run a mini-split directly on solar panels?
Yes, with a solar hybrid mini-split. Because solar panels already produce DC power and the mini-split's compressor needs DC internally anyway, a solar hybrid unit skips the extra AC-to-DC conversion step and can run straight off your panels during the day.
Why are inverter mini-splits more efficient and quieter than standard units?
Standard on/off air conditioners draw a big surge of inrush current every time the compressor starts, which is part of why your house 'rumbles' when it kicks on. Inverter compressors use three-phase, brushless DC motors that ramp smoothly between about 20 and 100 cycles per second, so they avoid that surge, run more quietly, and hold your set temperature more steadily.
What makes a solar mini-split different from a regular inverter mini-split?
A regular inverter mini-split takes AC power from the grid and rectifies it to DC internally to control the compressor speed. A solar mini-split takes DC power directly from solar panels, so it never needs that first AC-to-DC conversion step during daylight hours.
Do I need batteries to run a solar mini-split at night?
No. A solar hybrid mini-split can use the electrical grid as backup power at night or on cloudy days, blending in AC power as needed alongside whatever DC solar power is available. The grid effectively acts as your battery, and in most of the US power is cheaper at night anyway.
How much more efficient is an inverter compressor than a standard AC compressor?
Roughly 30% more efficient, according to Dave, mainly because it avoids the high inrush current of on/off compressors and runs continuously at a lower, more consistent speed instead of repeatedly cycling on and off.
Transcript
Read the full transcript
Hey guys, Dave with Airspool here. If you're new to solar, or to mini-splits, or to solar mini-splits, there are three terms that get thrown around that can be a little confusing: what's an inverter, what's an inverter compressor or inverter mini-split, and what is a solar mini-split or solar hybrid mini-split?
First of all, what is an inverter? An inverter is something that takes DC power and creates AC power. If you scope out DC power that comes from your solar panels, it looks like a flat line. AC power, the power we have in our homes, is 60 cycles per second and looks like a sine wave. In order to run your home with solar, you need to create that sine wave, and either you're sending that power to the grid, if you have a whole-house net metering agreement, or, what's becoming more common now that utilities no longer want to do net metering, you sell some of your power back to the grid and get a credit at night. Or you have your own battery system, your own inverter, and your own voltage controller. The solar comes off your roof into your voltage controller, or MPPT voltage controller, and gets stored in your batteries, which are still DC. That power then needs to be made into AC in order to run your home. So that's pretty straightforward: taking DC power and making it AC power is inversion, and that's what an inverter does.
Next, what is an inverter compressor or inverter mini-split? These days, I think it's fair to say the majority of mini-splits use inverter compressors, and the reason is they're more energy efficient and they last longer. Here's why: with a normal unit, you plug it into AC power, but that AC power needs to be rectified, meaning you take AC and turn it into DC. Why do that extra step? Because you need different types of sine waves in order to speed up or slow down the motor in the mini-split, called the compressor. If you don't do that, you get a normal air conditioner. You've probably seen it or felt it: when the air conditioner kicks on, your whole house kind of rumbles, and that's because of inrush current, where the motor has to suddenly start spinning.
Inverter compressors are different. They run on three-phase power, pretty fancy brushless DC motors, with electronics that let them start up at around 10 cycles per second and then run anywhere between roughly 20 and 100 cycles per second. That means you totally avoid the inrush current, and the unit ends up around 30% more efficient than a normal mini-split or whole-house unit. It also lasts longer because it isn't constantly turning on and off. There's a comfort benefit too: with a standard unit that keeps cycling on and off, you're thinking, "I'm too hot, when's the AC turning on," then it runs for seven minutes and you're thinking, "now I'm too cold, when's it turning off?" An inverter mini-split just chases your set point continuously. It's more comfortable, and because it's always running but at a lower, more efficient speed, it saves energy too.
So now, what's a solar hybrid mini-split, or solar mini-split? Remember, the power that comes from solar is DC. If we can use that DC power to run a mini-split, which needs DC internally anyway, we skip that first step where we'd otherwise take the whole house's alternating current and rectify it. Instead, you have DC power coming straight from your panels down into the mini-split, and you're managing that power to create the different frequencies and sine waves the compressor needs directly from the DC. That's a standard solar mini-split.
Of course, at night it's dark and you're not getting much solar, which is why solar hybrid mini-splits are popular: at night, the system blends AC and DC together. If it's a little cloudy during the day, the grid fills in the gap. Say you're getting 400 watts of solar coming in, but the unit needs 700 watts to run. That extra 300 watts comes from the grid, gets rectified, and blends in with the DC coming from the roof. Most of that power is still coming from DC during the daytime, but at night it's acting like a traditional hybrid inverter mini-split, running purely on alternating current, and it's still super efficient.
So, three different topics, and inverter shows up in all three, but here's how they're different. The goal, since we're a solar hybrid mini-split manufacturer, is to make use of that inherent DC power from solar to run your mini-split, then fill in alternating current as needed. That's how you run your unit for free during the day without needing batteries: the grid becomes your cheap battery. For most people in the United States, power is cheaper at night anyway, so you can lean on the grid instead of paying for a battery bank.
Thanks for your time. At Airspool, we talk about solar, we talk about mini-splits, and we talk about solar hybrid mini-splits. Thanks.
