Solar Powered Air Conditioner in a Sprinter Van

One of the reasons I have such a huge solar array (945 watts) and a huge battery bank (780 amphours) is so I can run an air conditioner. I went with a portable air conditioner called the Haier 8,000 BTU Portable Air Conditioner. I have the HPRB08XCM model. I selected this air conditioner because it was listed as using about 700 watts and it seemed to be sufficient to cool a well insulated van. In reality, it uses around 750 watts when the compressor is on with a peak startup power of about 2,760 watts. There is some loss when inverting from DC to AC. So you’ll actually need closer to 850 watts DC (70 amps at 12 volts). This means if you go with this air conditioner, you’ll need an inverter that can handle this peak current such as the Xantrex ProWatt 2000. It can handle 2,000 watts continuous and a 3,000 watt peak.

Installation: 

Installation was simple. I cut a well planned hole for the exhaust hose and one for the drain hose.

I slid this duct extension through the floor and used some adhesive on the outside.

On the outside of the van, I secured some metal mesh to act as a bug screen on the exhaust hose and the drain hose.

Any sort of tubing will work fine for the drain hose because it only drips out occasionally.

I left the wheels on because it wouldn’t sit flat without them. The AC is just strapped in place between two pieces of plywood.

The downside of the portable air conditioners is the exhaust hose. They can’t compete with the efficiency of the window units or the roof top units because the exhaust hose is always giving off heat. However, I did my best to mediate this by wrapping the hose with as much reflectix duct wrap insulation as I could. My exhaust goes through the floor, but placing the hose through the wall or through the ceiling would certainly work much better to remove the hot air. The less of the hose you have inside the van, the better it will work. I didn’t want to have a hole on the side of the van so I settled on the floor for the exhaust.

But Joe, how long can you run the AC?

If you don’t feel like reading all the information below, just watch this 10 minute video:

This will be a complicated answer with different scenarios. I think anywhere from 75-80 degrees is a good compromise while living the van life. The higher the temperature that you can comfortably tolerate, the longer the AC will be able to maintain it. In my experience, I’ve been able to lower the temperature approximately 5 degrees within a few minutes, then slower after that. So if it’s 90 degrees outside, I’ll compromise at 80.

Here are some different scenarios. Keep in mind the times listed below are compressor run times, not how long the AC is on. Once an AC reaches a set point, it only runs the fan and uses very little power. In other words, “how long I can run the compressor” is a typically a shorter time than “how long I can keep the van cool.” How often the AC cycles on and off will depend on how well insulated the van is. I’m ignoring all the other loads such as the fridge just to keep the numbers simple and minimize variables. I’d never actually run the AC long enough to the point where I couldn’t used any other loads.

1. Afternoon parked under direct sun: 9.5 hours

This is when it’s the hottest, but also the most common scenario. The current from the solar panels will carry some of the load, and the batteries will pick up the rest. So if the batteries are fully charged, and you’re still getting plenty of energy from the sun you might as well divert the extra energy into the AC. Most of the time, my batteries are fully charged before I even reach peak power from the sun. For example, 850 (maybe a few clouds) watts coming from the solar panels for 3 hours would be able to run the AC without ever depleting the batteries. Then the sun starts to set and perhaps I only take in 400 watts from the sun. Now 33 amps from the solar panels, and 37 amps from the batteries would be powering the AC. My battery bank is 780 amp hours (390 useable amp hours). This state of discharge may last for 2 hours and using up around 74 amp hours. Then the sun goes down completely. Way before this even happens, I would just open the door to cool off with the fantastic fan. For the sake of worst case scenario, I’ll keep going with this. So I’d have 316 amp hours left. I could run the AC for an additional 4.5 hours before my batteries get to 50%. In this scenario, The AC would be running full blast with the compressor on for 9.5 hours. Of course, Once the set temperature is reached, the compressor turns on intermittently to maintain that temperature.

2. Driving, then stopping: much greater than 9.5 hours

If I know it will be very hot at my next destination, I’ll have the AC running from the dash full blast while driving to cool off the whole van. It does a great job. I can park, and turn on the portable AC to maintain that temperature. So imagine the above scenario, but much longer because It will be using less energy to maintain a temperature rather than trying to lower a temperature.

3. Park in shade, or Night time: 5.5 hours

This is the least likely scenario. I can sleep comfortably with the fantastic fan on. If it’s a little warm I’ll also turn the AC on in fan mode only. However, If I do need to run the AC on battery power alone, I can do it for 5.5 hours. Again that’s 5.5 hours of the compressor trying to reach a set temperature. This number is the most accurate because it contains the least number of variables.

4. Night time and I need more than 5.5 hours: As long as I need to

If I was absolutely desperate and about to have a heat stroke in the middle of the dessert somewhere, I would crank the engine, turn on the dash AC, while charging the house batteries with my 200 amp alternator. The alternator will also pick up the load for the portable air conditioner. In reality, I’d probably just drive somewhere colder.

Also, this AC has a dehumidify mode. It uses a little less energy. I’ve experimented with it a little. It has a made a huge difference. A dry 85 degrees really doesn’t feel too bad at all.

How well does it cool the van?

It depends on the outside temperature and where I’m parked. The biggest challenge I’ve encountered was about 105 degrees outside while parking under direct sunlight. I was able to cool the van down to 85. On a typical day when it is around 90 degrees outside, it has no problem going down to 75 degrees inside. Living this lifestyle is all about making compromises. Keeping the van at 72 degrees all the time is a waste of my energy. You’d be surprised how fast you can acclimate to hot weather.

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  • Daniel

    Awesome post. I think if I make the move for a portable AC, I will try a two hose system through the ceiling. Not having an AC is a deal breaker in the hot humid south. I wonder how big of a factor your insulation is to making the temperature control efficient.

    • Joe

      I think insulation is one of the biggest factors in determining how much energy the AC will use to maintain a low temperature.