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Discussion Starter #1
Hi,
Ran across this video:
Shows David's experience with a 9000 BTU SEER 24 minisplit installed on his Class C RV for more than a year.
The minisplit provides 9000 BTU of cooling and 14000 BTU of heating -- the inverter motor/compressor allows it to operate efficiently at lower levels.
He operates the minisplit 24 - 7, 365 days a year. He says he has done this for more than a year without ever plugging in to shore power.

He goes over his solar system in this video:
Currently he has 8 PV panels at 180 watts each (1440 watts), but he has run the minisplit earlier with 900 watts of solar.
Six Battleborn 100 amp-hr Battleborn Li batteries.
He has a 3000 watt inverter/charger, but says the minisplit will easily run on a 1000 watt inverter.
Part of the reason for this robust (and expensive) electrical system is that he is converting to all electric, including an induction cooktop and an electric oven of some kind -- so, could probably make the minisplit work with less solar and less battery than he has.

He makes a case for the unit being able to stand up to road vibrations -- not sure I'm fully convinced of this, but he has run it for a full year on the road. Wonder if the warranty is voided with it mounted on a vehicle?

He says that his RV is very well insulated, but I would guess that a very well insulated PM could go with a 6000 BTU minisplit and less solar and battery to run it.

The main message to me is that he has run it for a full year and its still going strong, and he very rarely has to resort to anything but solar.

Gary
 

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Thanks Gary

This sounds impressive at first glance?

I have had "air" exchange heat pumps in my residences since the early 90s and found them to be a very good system(s). If I ever build again I would consider the efficiency of geothermal (obviously non-van related)
 

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An EER of 15 isn’t as high as the Mitsubishi mini splits, but the unit appears much smaller, which is a big plus for this kind of application; particularly if to be installed on a van. I did not compare sizes on specs — just going by looks (motorhome is large so may be an optical illusion). Also, if operated on turbo mode, EER will be even lower. SEER number is good but not the best as mini splits go.

Running 100% from solar is an impressive claim, but without knowing a lot more information what does it really mean? Is he camping in mild weather where it’s cool at night? What temperature does he set thermostat relative to outdoor temperature? How many hours a day does he really run it (24-7 stated, but who does that?).

I’d like to see the unit operate along the Gulf Coast in July or August before I’m a believer. The numbers just don’t add up under typical A/C conditions. Being a full-time boondocker, wouldn’t it be practical for him to relocate where A/C isn’t even needed?

Much more data is needed in my opinion.
 

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Discussion Starter #4
Hi,
He has 1440 watts of solar. PVWatts says that in Corpus Christie (on the gulf) he would get an average of 7.5 KWH per day (average of good and bad days).
The 15 EER gives a COP (efficiency) of 4.39, so 7.5 KWH would be give (7.5 KWH)(4.39 efic)(3412 BTU/KWH) = 112340 BTU for a day, or 4680 BTU/hr of cooling.
A bit less when you consider inverter inefficiency.
Maybe that's a bit short for a hot and humid day on the gulf -- not sure?

If you used the SEER 24 instead of EER of 15, the hourly cooling would go up to 7490 BTU/hr.

So, the SEER and EER differ by quite a bit -- which would be closer for a hot day on the gulf?

And, who in their right mind would want to spend July or August on the Gulf? :)

Gary
 

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Went to tksgiving outside Houston many moons ago......humidity was terrible.....also lived South Miami no humid sometime in October.....do not go to Texas gulf unless passing thru

Sent from my LG-H871 using Tapatalk
 

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In his part 1 video he says that on high it use less than 460 watts and on low it uses about 1/4 of that. Once it reaches the set point it only needs to run on low that's why he runs it 24/7, pick a temp and leave it.

Agree it would be nice to get readings in the hot and humid areas.
 

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In his part 1 video he says that on high it use less than 460 watts and on low it uses about 1/4 of that. Once it reaches the set point it only needs to run on low that's why he runs it 24/7, pick a temp and leave it.



Agree it would be nice to get readings in the hot and humid areas.

The ratings don’t support that claim if in hot weather. At 9,000 BTU/hr and EER of 15 (which applies to that 9,000 rating) requires 600 Watts to operate. Additionally, I know from personal experience that a motorhome that size barely stays cool with a 13,500 BTU/hr air conditioner when parked at the beach in Galveston, Destin, or Siesta Key, so a 9,000 BTU/hr A/C would run all out during most of day in summer.

I also expect that size A/C would run at ~ 9,000 BTU/hr or higher at least 10 hours per day. That alone is 6 kWh. Then there’s the other 14 hours a day requiring air condition, albeit at reduced rate.

The video seems taken in dry climate — probably out west — which could be at elevation in the mountains. Solar there could work better, humidity is low, it’s cool at night, etc.

Also, on video I noticed name tag suggested compressor can pull a lot more current, and thus power. I’m almost certain that the higher rated current applies to its maximum capacity around 12,000 BTU/hr, which could be near 1,000 Watts of power. It’s rated at 9,000 BTU/hr because it’s more efficient while still having reasonable capacity for a residential bedroom, etc.

Just saying there is a lot that’s not known. Based on A/C manufacturer’s performance data, and my experience with air conditioning Class Cs around that size along the Gulf Coast, I can’t see that unit working well enough strictly on solar in July or August to keep the average RVer happy.
 

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There was a Sprinter guy who separated the condensor and compressor of a mini split. It was a 240v unit too. Pretty cool setup.

Overlooking the issue of where the heck you put the ODU mini splits are the most efficient AC units out there.
 

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Discussion Starter #9
Hi,
While it looks like this system might be in the ballpark for summer, it does not look so good (to me) for climates that have a real winter...

The system produces enough heat to heat a van down to low temperatures -- its something like 14K BTU/hr, but it does not appear that the solar alone would provide enough energy output to run it 24/7.

If you look at what PVWatts says a 1440 watt system in Denver (a good winter solar location) would produce in mid winter, it comes out about 3.1 KWH per day average. The spec sheet for his minisplit in heating has a COP of about 3 (300% efficiency), so the the 3.1 KWH would be worth about (3.1KWH)(3.0 efic)(3412 BTU/KWH) = 31700 BTU heat output from the minisplit per day that could be provided from solar.

With an outside temperature of 30F, my van requires about 3500 BTU/hr to maintain 65F inside, or about 84000 BTU/day if you heated 24 hours a day as he does. So, it seems like the minisplit with 30F outside in Denver would produce less than half of the required heat from just solar.
In a worse solar location than Denver (eg Bozeman, MT where I am), the solar output is only about half what Denver is, so solar would provide less than 1/4 of the needed heat at a 30F average outside temperature.

I'm inclined to think like Chance that maybe he moves north in the summer and south in the winter -- not such a bad lifestyle :)

If you have the camping style of driving during the daytime so that you were using the van heater during the day and the 600 amp-hrs of battery would be fully charged (by solar and the van alternator) at the pull into the campground time, then I think the about 7 KWH stored in the batteries would get you through the night with temperature down to the mid 20's F, or maybe lower with better insulation and/or a cooler van inside temperature than I have. But, I think I would want to have some type of backup fossil fuel heater for real winter camping.

Gary
 

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Gary, it would also be difficult to fit that much solar (1400 Watts) on your van.

Additionally, 3.1 kWh can be charged by an oversized alternator in much less than an hour, so ultimately those who drive daily will find solar of much less value. When you have a + 200 HP engine available, and need a lot of electricity, solar just can’t compete in my opinion. I think I would invest the added cost and weight on more batteries instead.
 
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