Solar Air Conditioner

[Opusdei]

As a owner of a 40ft class A. Living in Texas Ac is required. Can you make a system that will operate at 40 DB. Current Ac systems operate at 72 Db.

Good news! Noise is a whisper level. 41/38/33 dB per Hi/mid/low wind speed. 12V DC air conditioner can improve the bottom line while keeping a truck cab cool and quiet without idling noise.

 

[Trukinbear]

Aha! Sounds like Prius has an electric motor to run A/C. It takes 20 minutes to drain the auxiliary battery before the alternator starts to re-charge the battery.

The Prius's battery has an absolute capacity of 6.5Ah @ 201.6V or 1.314 KwH - but the BMS keeps it between 80% and 40% leaving a useable capacity of 524wH (.524KwH). However it usually strives to keep it around 60% to have available capacity to capture energy via regenerative braking, so unless I just came down a mountain, or sat power braking for a while to get the battery to 80%, when I park the battery is ~60% and the engine will crank back up at 40% so I've got 20% available to run the AC. So 262wH over a period of 20 minutes gives us 786 watts average consumption for the AC compressor and blowers. Not as efficient as my 12k BTU mini-split heat pump although the BTU of the Prius's AC system is a big unknown... so maybe.

PS Prius has neither a starter nor an external alternator - it converts the 201.6VDC with a change to AC and back to 12.6V to run the car's 12V systems and charge the little 12V battery in the back - without which the Prius won't start because it needs a signal back from the brake computer.

 

[Mango boat]

I'd be interested in a DC system to use on a sailboat/marine environment.

 

[Opusdei]

I would like to thank everyone for your comment. It gave me a moment to take a honest look at myself and the business. Is it really a case for business? Will the customer like it if I build it? Who do I know if I have a question? I really appreciate all of your inputs from the DIYsolarforum.

 

[David S]

I'd venture to say that many here would be interested in a 12v or 24v Mini Split configuration similar to your pictures, but focused RV applications. My 37' motorhome has 2 Coleman 13.5k btu roof units. If I could replace those units with mini-splits with condensers on the roof, at a 21+ SEER rating, I'd do it in a minute. After I finish my 24v solar upgrade, I'd do it in 30 seconds . All assuming the price is in the ballpark, of course.

 

[Mango boat]

...I really appreciate all of your inputs from the DIYsolarforum.

This could be a very popular marine unit if you can make it efficient. Have you thought about using water/sea water as a heat exchanger in the condenser? A small 12v water pump to circulate raw water across the coils would increase the cooling effect considerably.

 

[Opusdei]

I'd venture to say that many here would be interested in a 12v or 24v Mini Split configuration similar to your pictures, but focused RV applications. My 37' motorhome has 2 Coleman 13.5k btu roof units. If I could replace those units with mini-splits with condensers on the roof, at a 21+ SEER rating, I'd do it in a minute. After I finish my 24v solar upgrade, I'd do it in 30 seconds . All assuming the price is in the ballpark, of course.

I made a comparison chart for RV. Pricing for 12V air conditioner is based on DC option, so a shore power should go DIY.

 

[Opusdei]

This could be a very popular marine unit if you can make it efficient. Have you thought about using water/sea water as a heat exchanger in the condenser? A small 12v water pump to circulate raw water across the coils would increase the cooling effect considerably.

I like you idea of intermediate cooling. However, water freezes during winter and it could damage the copper pipe. I guess that's why A/C uses R-134a gas.

 

[Forbisher]

I would like to thank everyone for your comment. It gave me a moment to take a honest look at myself and the business. Is it really a case for business? Will the customer like it if I build it? Who do I know if I have a question? I really appreciate all of your inputs from the DIYsolarforum.

Make an Indiegogo campaign for your air conditioner.

 

[David S]

I made a comparison chart for RV. Pricing for 12V air conditioner is based on DC option, so a shore power should go DIY.
View attachment 23781

One of the biggest challenges with replacing RV air conditioners with traditional mini-splits is that the condenser/compressor combination must be vertically mounted. The only logical space for this unit on most RV's is the roof. Adding 24-36" inches to my already >144" tall RV is a poor choice :D. Thus, your horizontally mounted unit is interesting. I'm building a 24v system because I want to have smaller wires and a lot of solar panels on relatively inexpensive SCC's. A 15a 24v version of your AC unit would be super cool

 

[Opusdei]

One of the biggest challenges with replacing RV air conditioners with traditional mini-splits is that the condenser/compressor combination must be vertically mounted. The only logical space for this unit on most RV's is the roof. Adding 24-36" inches to my already >144" tall RV is a poor choice :D. Thus, your horizontally mounted unit is interesting. I'm building a 24v system because I want to have smaller wires and a lot of solar panels on relatively inexpensive SCC's. A 15a 24v version of your AC unit would be super cool

That's right. While traditional mini-splits must be vertically oriented, DC compressor can be installed in any direction. 24V model is more powerful 8800 BTU but consumes ~20A of power. I focus on developing 12V model for trucks (see the attached photo) and 24V model will be available later.

 

[David S]

That's right. While traditional mini-splits must be vertically oriented, DC compressor can be installed in any direction. 24V model is more powerful 8800 BTU but consumes ~20A of power. I focus on developing 12V model for trucks (see the attached photo) and 24V model will be available later.

There is already at least one major player getting into truck ac's at 12v domestically. Dometic makes them here:

Dometic Truck 12v AC

That 24v unit would be SWEET.

 

[Opusdei]

There is already at least one major player getting into truck ac's at 12v domestically. Dometic makes them here:

Dometic Truck 12v AC

That 24v unit would be SWEET.

Dometic is one of the best RV air conditioner manufacturers. Their 12V model will be a drop-in replacement with traditional rooftop models. Mini-split installation will be more suitable for trucks where there is no 40cm x 40cm opening on the roof. Thanks for a good info.

 

[Sparky]

That's interesting. Prius had a solar option. I'm wondering if the Prius solar panel provided 12V electricity for the A/C without the need of idling - for your dog.

The prius solar collector option had a dismal return. There just isn't enough flat space on a prius for an effective solar mount, and if you added one you killed its efficiency by adding drag.

 

[cwstnsko]

They run at 208/230vac, so I have to account for a split phase inverter setup when considering both up front costs and power consumption. They're both ~$1500 - slightly less than the DC units I've found. The consumption on those, though, is prohibitively high

With the popularity of RV boondocking, I have a lot of interest and I think there is a decent sized market for effective DC high efficiency mini-split AC units for solar powered mobile applications. I think the OP's idea is more applicable to the mass automotive market, but I'm not sure how big that market is, and with electrification of more and more cars, it may be shrinking.

I have a couple questions related to the above comments.
1) do you think the units really need a split phase inverter, or would a single phase 208/204 V work? I could see the importance of split phase if you were depending on the same inverter(s) for your 120V needs as well, but if the inverter were dedicated to the mini-split, it seems like single phase 220-240V would work probably work fine, unless the units need the neutral connected.
2) Do you think the HotSpot unit has higher draw because it is less efficient, or just because it is a much larger capacity (12k BTU) unit. I'm not sure that it takes more Wh to deliver the same cooling as the smaller units, if it is only being asked to deliver 6-8K BTUs. It would seem that the inverter losses would more than cancel out any advantage the smaller units might appear to have.

I think many on here who are scheming around mobile off-grid living quarters may be a slightly different market than what the OP is targeting, and many of us have started to embrace a higher voltage system as one way to overcome the challenges of huge current at 12V, hence all the comments about 24V offerings being preferred.

I'm currently acquiring supplies to bring my RV up to about 17kWh total battery storage with 1200-1400 watts of PV. I've been steering towards 48V and thinking of the Hotspot, but since I would probably be mostly concerned with cooling the rear 7x8 ft bedroom, 12k is probably serious overkill and I'd expect to be running the unit at much lower consumption than the rated consumption at full output.

The Dometic Truck Coolers posted above look very interesting depending on the price as it would be dead simple to swap out my bedroom fantastic fan for one of those. It surprises me that their website only shows 12V offerings coming soon, but says much of the testing was done in AUS. I would think a 24V model would be the norm there.

 

[Opusdei]

The prius solar collector option had a dismal return. There just isn't enough flat space on a prius for an effective solar mount, and if you added one you killed its efficiency by adding drag.

My minivan didn't suffer the air drag even if I added two mono panels and solar air conditioner. Prius is probably so efficient as to be severely affected by the head wind.

 

[Opusdei]

With the popularity of RV boondocking, I have a lot of interest and I think there is a decent sized market for effective DC high efficiency mini-split AC units for solar powered mobile applications. I think the OP's idea is more applicable to the mass automotive market, but I'm not sure how big that market is, and with electrification of more and more cars, it may be shrinking.

I have a couple questions related to the above comments.
1) do you think the units really need a split phase inverter, or would a single phase 208/204 V work? I could see the importance of split phase if you were depending on the same inverter(s) for your 120V needs as well, but if the inverter were dedicated to the mini-split, it seems like single phase 220-240V would work probably work fine, unless the units need the neutral connected.
2) Do you think the HotSpot unit has higher draw because it is less efficient, or just because it is a much larger capacity (12k BTU) unit. I'm not sure that it takes more Wh to deliver the same cooling as the smaller units, if it is only being asked to deliver 6-8K BTUs. It would seem that the inverter losses would more than cancel out any advantage the smaller units might appear to have.

I think many on here who are scheming around mobile off-grid living quarters may be a slightly different market than what the OP is targeting, and many of us have started to embrace a higher voltage system as one way to overcome the challenges of huge current at 12V, hence all the comments about 24V offerings being preferred.

I'm currently acquiring supplies to bring my RV up to about 17kWh total battery storage with 1200-1400 watts of PV. I've been steering towards 48V and thinking of the Hotspot, but since I would probably be mostly concerned with cooling the rear 7x8 ft bedroom, 12k is probably serious overkill and I'd expect to be running the unit at much lower consumption than the rated consumption at full output.

The Dometic Truck Coolers posted above look very interesting depending on the price as it would be dead simple to swap out my bedroom fantastic fan for one of those. It surprises me that their website only shows 12V offerings coming soon, but says much of the testing was done in AUS. I would think a 24V model would be the norm there.

1) They are both DC air conditioners so there is no need for an inverter.
2) I think HotSpot would be more powerful and maybe more efficient. The higher DC voltage would make it more efficient. What makes them different from my proposal is whether it is mobile off-grid or not. HotSpot air conditioner is made for stationary living quarter, not for RV and trucks. Dometic 12V is a drop in replacement to their rooftop 110Vac air conditioner while my proposal can be applicable to any type and anywhere (and much cheaper).

I think the main reason Dometic offers 12V is because it is a typical vehicle alternator voltage. Unless you are connected with a shore power via AC/DC inverter/charger, 12V alternator is a good source of energy for off-grid battery-powered application even if you have solar trickle charging option.

 

[David S]

Dometic is one of the best RV air conditioner manufacturers. Their 12V model will be a drop-in replacement with traditional rooftop models. Mini-split installation will be more suitable for trucks where there is no 40cm x 40cm opening on the roof. Thanks for a good info.

I was giving this some more thought, and it occurred to me that the 40x40cm opening in the roof, and the attendant all in one design, is not a "good thing". In fact, I'd love the opportunity to replace the two AC units on my rig with vent fans by using a true mini-split with a rooftop mount design. Remove the old AC, install a fantastic fan and then install the new mini-split adjacent to the vent. That would allow me to benefit from the significant efficiencies that come from splitting the units (one of the hallmarks of the mini-split design). Now, about that 24v version... :D

 

[ghostwriter66]

I made a comparison chart for RV. Pricing for 12V air conditioner is based on DC option, so a shore power should go DIY.
View attachment 23781

These prices are out of whack .. we purchase ALLOT of A/Cs and I will tell you the last COLEMAN MACH 15 we got we got for 599.00 at MY 12 VOLT STORE not 1030 ...

ZERO BREEZE is a FRICKIN JOKE so don't count that - you can also get knock offs from Alibaba for ZERO BREEZE for $399...

and we got the DOMETIC B59516 for $596 ...

SOOO YOUR numbers are way off ... I am going to tell you -- you are going to SINK in this market -- you need to do better market research ...

 

[Opusdei]

These prices are out of whack .. we purchase ALLOT of A/Cs and I will tell you the last COLEMAN MACH 15 we got we got for 599.00 at MY 12 VOLT STORE not 1030 ...

ZERO BREEZE is a FRICKIN JOKE so don't count that - you can also get knock offs from Alibaba for ZERO BREEZE for $399...

and we got the DOMETIC B59516 for $596 ...

SOOO YOUR numbers are way off ... I am going to tell you -- you are going to SINK in this market -- you need to do better market research ...

Don't get me wrong, I'm not selling a Zero Breeze. Price table carries the usual disclaimer "Price estimate is based on Amazon 9/27/20" so number is correct. You purchase ALLOT of A/Cs and that is wholesale merchant price. Amazon Prime delivery and free 30 day return gives online customers a peace of mind.