TIP : Very Energy Efficient Air Conditioning for Solar Systems

As you know we have a solar system…3.8kw Canadian Solar PVs, 400ah LifePo4 batteries, 5kw Victron inverter powering a 120vAC household system. Originally we were not going to have air conditioning…but a summer of me building the house changed my mind quickly. So the next summer (2020)…we had an older standalone upright AC unit that we pressed into service. Mistake! Terribly inefficient, power hog, loud enough to make conversation uncomfortable, and didn’t get the house below 80 degrees.


The issues/problems that we faced were:

  1. Not enough AC power for a regular whole house AC system.
  2. Only 120vAC power.
  3. 915sq’ of living space in 4 rooms (master bedroom, spare room, bathroom, & great room that includes a kitchen).
  4. Not enough available wall space for a split unit.

Bottom line…we had little other choice than a window unit. But they are notorious for being anything but energy efficient as well as being limited in total square footage vs BTU…not to mention noisy. As I said…few options…limited selection…yuck. So into research mode I went.

I found inverter technology as an alternative to standard air conditioner technology. So what is this inverter technology? Basically is converts incoming AC power into DC power. Then it regulates that DC power to the unit through a modulation process. Meaning…it only uses the bare minimum power required at the time for the temperature setting vs room temperature. And since DC power is more efficient on electric motors and compressors you get longer life out of them as well. The result in power savings is around 35%.

And as an added benefit I found a unit that is 9 times quieter than traditional AC units. Yeah, quiet as a library. Nice!

Now it was time for a trial…we decided to try it out on our 224sq’ master bedroom…after all a decent night sleep with AC is worth a whole lot!

We purchased a “Midea 8,000 BTU U-Shaped Smart Inverter Window Air Conditioner” for our trial run. It was rated to cool 350sq’ giving us a 40% margin…meaning that the AC unit should be able to 100% cool the room running at 60% capacity. We bought it from Amazon for $389 (tax included).

It was very easy to install, very quiet, super energy efficient, and froze us out 🙂 We considered it a success in every way. It was even quiet enough to allow me to sleep uninterrupted, and that is rare for me. So we bought the second unit a month later. This time we bought a 12,000 BTU unit (rated for 550sq’) for the great room / kitchen which is 460sq’… for $465.

It was a very nice summer & fall and the solar system could handle the power load with no issues. We even ran it into the night till 10:30 a couple times…still over 80% on our batteries.

This year when I put them back into service I placed the 12,000 BTU unit in the great room again but a different window that was protected and shaded. The 8,000 BTU unit went into our spare room which opens into the hall that opens into the bathroom, the master bedroom, and the great room. So far we are super pleased with the AC cooling power set-up we now have. And we don’t even have to run the AC’s after sunset…if that long.

Why not put the AC unit back in the master bedroom? Well, it was in my window the summer before so no cool breezes for me at night. This year…ahhhhhhhhh…cool summer night breezes every night through an open window.

We do have ceiling fans in the master bedroom and the great room / kitchen that keeps the cool air moving. I contribute that to the master bedroom staying at a very comfortable temperature all day.  We usually keep the great room / kitchen set at 71 degrees and the spare room set at 67 degrees. This keeps the whole house very cool and comfortable.

The maximum AC power draw on the 8,000 BTU unit is 8.75 amps and the 12,000 BTU unit comes in at 12 amps. However, when I look at the user screen on the solar system computer I rarely see them drawing more than about 8 – 12 amps total combined. So realistically, if I have them both running, they are drawing no more than 21 – 30 amps off the batteries at any one time. Considering that the PVs are producing 50 – 70 amps during the day…I am getting free AC and still charging the batteries.

I love these AC units! They are super energy efficient and very, very quiet. If you have a solar system and no AC but you want AC…these are the units for you! If you currently use grid power and have older energy inefficient window AC units…you might want to consider upgrading to these units.

Unit information:

  • ULTRA QUIET – The Midea U Smart Inverter AC unit is 9 times quieter than traditional units. The U-shape design uses your window to blocks noise outside and the high efficiency Inverter system warrants ultra low noise and vibration. This design allows for extremely quiet operation as low as 42 dBA – almost as quiet as a library – so you can get a restful night’s sleep or binge your favorite shows undisturbed.
  • MORE THAN 35% ENERGY SAVINGS – With the advanced DC Inverter technology, Midea U achieves over 35% energy savings compared to other traditional units, and it’s the first window AC to obtain the ENERGY STAR Most Efficient 2022 Certification. You may also get exclusive benefits from your local energy distributor.
  • FLEXIBLE WINDOW OPENING – Midea U-shaped design allows your window to open, bringing fresh air into your home anytime and allowing you to maintain more of your view even when the unit is installed. The Anti-Theft Mechanism locks the closed window for added security
  • SMART CONTROL – The Midea U Smart Inverter Air Conditioner is Wi-Fi enabled and can be controlled from anywhere through the cloud using the MideaAir app on iOS or Android. You can also use voice commands throughout your house, office, or apartment using Alexa or Google Assistant.
  • ROBUST INSTALLATION – Install the included quick-snap bracket, set the unit on the bracket, and secure the sidearms. After that, you are all done and ready to enjoy. Available for single-hung or double-hung windows with size: 22″-36″, minimal height at 13.75″.

For the 8,000 BTU, 350sq’ unit < click here >

For the 12,000 BTU, 550sq’ unit < click here >



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5 thoughts on “TIP : Very Energy Efficient Air Conditioning for Solar Systems

  1. My son bought a couple of those U shaped inverter AC units for his old house. He loves them. Yes they are very quiet, he has one just overhead in his bedroom and the power consumption is minimal.

    Liked by 1 person

  2. Pingback: Very Energy Efficient Air Conditioning for Solar Systems — A.H. Trimble – Emergency preparedness information for disasters and grid-down – chazrothmsg

  3. As always, thanks a million for your articles and insight. You began this article with “As you know we have a solar system…” I couldn’t find any links to details and my searches of your site were fruitless. Could you please point me to specs/design/choices for your system? I’d love to be able to replicate it! Thanks again.

    Liked by 1 person

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