Reimagining Solar With Heat & AC

Topic: Reimagining Solar With Heat & AC (Read 1965 times) previous topic - next topic

Reimagining Solar With Heat & AC

April 17, 2022, 03:26:24 pm

If one considers switching from the typical roof air conditioning system on coaches to a ductless mini-split heat pump system, that opens up lots of space for added solar on the roof. With the added amp hours of lithium batteries do you think it is possible to run a mini split system on solar?
I'm not that good at figuring amp hours vs usage but my thinking is it would be possible.
Here are is some Google search results for 12,000 btu mini split AC units...
most efficient mini split 12000 btu air conditioner - Google Search

Re: Reimagining Solar With Heat & AC

Reply #1 – April 17, 2022, 04:38:14 pm

Good point about opening up the roof for more panels. The high seer ratings do use less power with the high end compressors so should require less draw to start up and a low wattage once the temperature is stabilized. Other vents and skylights could also be modified to give more room up top.

Seems easy to plan for daytime operation with our existing panels. But more battery capacity will be needed for climates where the evenings are hot and humid. I should have ours operating in a couple of weeks once all the cable, etc arrives and will put a meter on it to check for startup, cool to temp and maintain temp wattage draws. The seer is 21. Will also be interesting to see the watts used for heating since it also has that capability.

Pierce

Re: Reimagining Solar With Heat & AC

Reply #2 – April 18, 2022, 12:24:55 am

How about 38 SEER? Available on Amazon, rather than post a link just recommend you use the forum link to Amazon, and search for this: Gree 9,000 BTU 38 SEER SAPPHIRE Wall Mount Ductless Mini Split Air Conditioner Heat Pump 208/230V

Re: Reimagining Solar With Heat & AC

Reply #3 – April 18, 2022, 02:32:51 am

Claiming a 38 SEER makes me wonder.

Almost twice the SEER of its siblings

Re: Reimagining Solar With Heat & AC

Reply #4 – April 18, 2022, 10:24:10 am

Quote from: TGordon – April 18, 2022, 02:32:51 am

Claiming a 38 SEER makes me wonder.

Almost twice the SEER of its siblings

Of course. There are, however, numerous other units available with SEER ratings in the 30's, and becoming more common daily. But as President Reagan so famously said, "Trust. But verify."

So, if 38 SEER is correct, on this Gree unit, you're making 9K BTU and consuming approx 240 watts. The original Dometic Penguins, which are still happily cranking it out on my coach most likely have an effective SEER around 7. So at 9k these BTU Penguins are consuming around 1290 watts for the same cooling.

One other takeaway, the Dometic units are 24 years old and still going strong.

Re: Reimagining Solar With Heat & AC

Reply #5 – April 18, 2022, 11:00:01 am

Look at how many members have mounted the condenser of a mini split. Only one and his is a GV. One other was into refrigeration and split a package unit putting the condenser half in a bay. Getting all the higher SEER has a major installation problem with a mini. The higher SEER may make it on our roof in the future is my thinking.

Re: Reimagining Solar With Heat & AC

Reply #6 – April 18, 2022, 12:01:13 pm

This mini seems to spool up on power use . The wattometer reads low , the fan comes on low, the ECU thinks about the situation, and parts come on line as it gets to work . This is back wards to the roof units that shock the power system .

The max watts read were about 1180. I will read it again . Right, about 1100 watts max and 10.8 amp . Max amps is 11.8 .
The first min reads about 650 watt and works up to max watts as the head pressure builds. Today is only 83 * with the temp set to 73.
Thats still about 100, 12v alternator amp , minus transfer loss.

Eco mode is 730 watts running at 76* 7 or less amps.
So yes. 1000 watts running / 900 typical use running my 19 seer , 12000 btu unit Math says it should run off of a 2000 watt array. FWIW there are 2 or more minisplits on the FT forum. Many more online . Its been done, it works .

Re: Reimagining Solar With Heat & AC

Reply #7 – April 18, 2022, 02:24:21 pm

Just ordered ours SEER of 21.5 looking to put the compressor unit in the storage bay and put louvers in the bay doors, one exhaust and one for intake,

Re: Reimagining Solar With Heat & AC

Reply #8 – April 18, 2022, 03:11:49 pm

Mine fit under the front fender. Same place for both coaches.
Inside unit fits above door.
The compressor is turned a little so that air enters and exits easier

Re: Reimagining Solar With Heat & AC

Reply #9 – May 06, 2022, 02:57:33 pm

This 12000 BTU unit will run with 6 245 watt solar panels . I have 3 working now and will add 3 .
It runs swell powered by the additional alternator and the 3 panels . Everything is working hard tho. and 3 more panels and controller will let it all cruise easier.

Re: Reimagining Solar With Heat & AC

Reply #10 – May 11, 2022, 01:41:41 pm

Another ignorant question.. I have these panels working well and feeding my 2500watt inverter . Everything seems to work fine.
I have unplugged the chassis 120v batt charger to verify that the system will work without shore power. It does.
My question. Should I leave it plugged in when I have the juice to save the battery cycles?

Also FWIW, I am adding 3 more panels . The return on investment is pretty quick if it will run the AC without the gen set . It appears that it will .
More...Quick EditQuote Dup post with solar allover the place here. But this is where I'm at today . Adding the second set of used 245 watt panels .
My total cash outlay is about $850 for about 1200 watts.

Re: Reimagining Solar With Heat & AC

Reply #11 – May 11, 2022, 03:25:55 pm

Quote from: Protech Racing – May 11, 2022, 01:41:41 pm

My question. Should I leave it plugged in when I have the juice to save the battery cycles?

If you are not paying for shore power, I would.

Being plugged into shore power will save you battery cycles but will it save you money if you are paying for the grid power. I have no idea what would be cheaper in the long run but I bet Roger knows.

Re: Reimagining Solar With Heat & AC

Reply #12 – May 11, 2022, 04:00:51 pm

Last year we installed 3 Gree 24000 units. 2 in our shop/garage and 1 in to our office. We are very pleased. Installation was very easy to do, almost plug and play. I wonder how practical would be to set up the outside unit in a portable manner. My idea is to fabricate a set up where all the connections and the coper lines from inside unit will be at the back so the outside unit can be set on a hitch tray.
Of course use quick connecters to minimize freon loss during connect/disconnect.
Split units are so quiet and efficient.

Re: Reimagining Solar With Heat & AC

Reply #13 – May 13, 2022, 12:46:01 pm

3 more
Copper brake line to fish the cables.

Re: Reimagining Solar With Heat & AC

Reply #14 – May 13, 2022, 05:21:33 pm

It works. The panels are struggling a little but the battery voltage is maintaining at 12.3
I don't hate the install.
The inverter output shows 7 amps at AC start. Now on ECO mode it is steady 3 amp s at 122volts. So about 500-800 watts.
The PV controllers show 26- 30 volts. One set shows 7-9 amps . The 230 watt set shows 4 amps. The 230 set is more shaded right now.
I'll check over the next few days and verify that the front set are going to stay. I may find some 440 watt take offs but he wants $250 per for those,

Re: Reimagining Solar With Heat & AC

Reply #15 – May 13, 2022, 05:51:46 pm

Valence U1-12RT 12.8v 40Ah Lithium Iron Magnesium Phosphate Battery | eBay
Next piece of the puzzle . Batteries.

Re: Reimagining Solar With Heat & AC

Reply #16 – May 25, 2022, 09:52:58 pm

Quote from: fatheeler – April 18, 2022, 02:24:21 pm

Just ordered ours SEER of 21.5 looking to put the compressor unit in the storage bay and put louvers in the bay doors, one exhaust and one for intake,

Notes;;; Tip the indoor unit towards the drain at least 3/8 of an inch . Maybe a touch more. This way you dont have to be dead level to use the AC.
I have my bus run up on blocks , with service pipes in the rear axle .
AS the front bags lost air and the rear has the service pipes , I now have about 6 in lower nose than the rear and the AC wont drain.

Re: Reimagining Solar With Heat & AC

Reply #17 – May 26, 2022, 03:16:55 pm

good thought I was going to make level, now if the weather will cool a bit so I can work on it 96 today,

Re: Reimagining Solar With Heat & AC

Reply #18 – June 05, 2022, 02:36:21 pm

I reinstalled the 1000 watt inverter near the solar charge controllers.
While the AC was full on with full sun, I had an inverter overheat -fault shut down. The box was too hot with little airflow. I cut a hole facing the fuel tank and added a fan to pull air into the box with the air exit on the box floor, just a few holes near the step. I run my outside power chord out of one of the holes. I was going to use the fan to evacuate the box but it ran nicer and quieter sucking air .I was too lazy to slide under and fit the fan on the chassis side of the box. Maybe in the future.. It seems to function well .
I have not had another overheat shut down but the fan only ran one time so far. It appears to be set at around 150F . The Inverter runs its fan at 44C and shuts off at 50C .
It moves a lot of air and is controlled by another Autozone fan control system .
I have 4 total running the engine cooling fans as well as the electric box cooler . I have used these a lot over t he years and I cant remember changing out a failed unit.
FWIW, I also covered the lower buss bar with insulating tape in case one of the hot wires falls/fails etc. I hate fires.

The solar keeps up with load very well with the AC set into ECO mode and 77*. My 6 -240 watt panels work pretty hard ( 50 amps total) supplying the 5 amps to the AC. ECO mode wont cool the bedroom tho . Funny thing, the most AC is needed when the sun is out the most.. So its kinda of a self controlling balance it seems.

Re: Reimagining Solar With Heat & AC

Reply #19 – June 15, 2022, 10:21:48 pm

Update. First real world test in the last 2 days.
The limit is over heating of the pure sine wave inverter and total amps delivered.
Driving down the road , I have the 6 panels for about 55 amps max , plus my Delco one wire 119 amp alternator direct feeding the 2 house batteries.
As long as the sun is full on , I can use the ac at normal rate And keep the bus mostly comfortable. It is 96 degrees air temp and not Icey inside . Good but not chilly at all.
This needs to be optimized a little better for over the road. Sitting still , I can leave the box door open and the parts stay cool enough to run everything. The solar also runs my engine cooling fans directly from the batts .
I need more solar . And more cooling .
The ac draws 4-7 amps at 122 volts and that means at least 80/100 amps of 12 volts amps .

Re: Reimagining Solar With Heat & AC

Reply #20 – June 17, 2022, 12:35:32 pm

Those that know more than I about batteries.. Please advise the purchase of these;

LIFEPO4 Battery with BMS 45Ah Inventus U1-45 Rechargeable Lithium Iron...

Or these. ;12V 45Ah 60Ah 220Ah 300Ah / 24V 100Ah Lithium iron LiFePO4 Battery BMS Solar...

Please keep in mind that we are financially challenged . Retired, racer, engineer.

Re: Reimagining Solar With Heat & AC

Reply #21 – June 17, 2022, 01:03:26 pm

Quote from: Protech Racing – June 17, 2022, 12:35:32 pm

Those that know more than I about batteries.. Please advise the purchase of these;

LIFEPO4 Battery with BMS 45Ah Inventus U1-45 Rechargeable Lithium Iron...

Or these. ;12V 45Ah 60Ah 220Ah 300Ah / 24V 100Ah Lithium iron LiFePO4 Battery BMS Solar...
Please keep in mind that we are financially challenged . Retired, racer, engineer.

Our toys and travel keep us perennially financially challenged. Race cars and aircraft keep you in the poor house but the memories.

Our town makes me play Scrooge in the Xmas play each year. I have not hit the restaurants for cooking oil diesel yet but I've got plans...

This next year is going to be a challenge for many companies so watch FB Marketplace for the battery deals, I did and our solar AGMs that listed for $435 were only $35/ea. Still going strong over 13 years later. A big box truck came to Sacramento with hundreds in it. I should have bought as many as the Vanagon would carry without popping the tires.

Pierce

Re: Reimagining Solar With Heat & AC

Reply #22 – June 17, 2022, 04:45:57 pm

I was reading about the ac/dc fridge dilema that I am pondering. I understand the inverter has to be sized for the inrush flow of electric to start the ac fridge, whereas the DC fridge doesn't have that issue.

Re: Reimagining Solar With Heat & AC

Reply #23 – June 17, 2022, 05:23:03 pm

Many new residents fridges use the inverter style of power and don't shock the power system.
Just like the mini split ac units.
Just look for a modern unit. Energy star rated .

Re: Reimagining Solar With Heat & AC

Reply #24 – July 06, 2022, 01:16:59 pm

The Solar/ AC works very well up to about 88* . Over that and I need more cooling of the inverters and the AC needs more amps.
I parked in the sun at Watkins Glen International and the solar ran everything we needed. I ran the gen set just to use the microwave to defrost some ZWeigle while hots .
For florida . I need another 600 watts or more.
So to duplicate a usefull system. Figure your AC watts at 1500 and do8ble that for the solar watts .
Its a lot but doable and so nice not to run the Gen set , IMHO.

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