solar powered secondary AC system for keeping cabin and battery temps down

I have this (seemingly) wild idea to use a mini AC compressor, solar panel, separate or additional 12v battery, and a fan, all to keep the cabin cool enough to not over heat the battery, thus degrading it.

My first idea which was low cost would have been an exhaust fan that I would mount to the rear cabin vent exit, which I believe is where the battery fan blows its air out, or at least tries to. I have not attempted this yet because I have yet to put ceramic film on the windshield yet, I must exhaust the more common tactics forst before I venture down this road.

Now for the parts. There does exist a coke can sized compressor that uses 300W max and is variable speed so 100-300 watts. In reality this only needs to cool the immediate area of the battery, I can isolate/insulate the battery but in the event of a failure would heat the battery up even worse...
Obviously there exists batteries and solar panels as well as charge controllers to maintain the system electrically. To keep the system hidden and clean a 100ah lifepo4 would be sufficient given an isolated charging system, bonus points if I can get the inverter to charge it and shut of the secondary HVAC, or fan when the car is running, whichever happens to more viable.

For the AC a condenser and fan could be mounted externally, underside in the rear. As the power requirements add up, a larger roof mounted solar panel to lug around would be paramount.

After further thought, I realized the engineering feat this would be as the cooling parts of the compressor would need to pass to the battery fan...or I could just AC the cabin for second place results.

Another related question I pose is how I could maintain the 12v OE car battery via solar to lessen the load on the inverter, maybe gain some efficiency?

12V Mini Compressor

 

Where might I find one of these solar panels to retrofit? Or are they generic? Im assuming not sunce this was OEM.

 

Have you used these? Ive read enough reviews to find out that they are very bad and or ineffective.

 

HVAC was bit of an extreme pipedream lol. If I could just get the fan to run when the car is off to evacuate the hot air or adapt the feature of the solar roof gen 3s that would suffice.

 

Well is the fan physically different? I can look up the parts on ebay and see used ones. Im not worried about the factory solar panels, I can build a power solution for that easy. I may just double the 12v batteries and put a charge controller on a relay off circuit with an aftermarket solar panel on the roof (roof rack options would be nice). Or I could wire it up to a solar panel in the front, but the most economical would be to attach it to a roof rack cross bar system.

 

Im investing in repelling sunlight/UV first. The weathertech shades full set is a custom fit. I wont leave all of them on the windows, but the rear one I might leave there...carbon ceramic on the windshield would do wonders and its already in the pipeline. Baby step the improvements.

After looking at a used fan for both a 2012 prius and a 2012 prius V, I cannot tell the difference other than a part number. gonna have to look up dealer parts to get a PN and then look for a used one. At least this way I have a spare I can butcher to experiment with, the brushless motor variant. Put in on a 12 volt supply at my work and experiment with thermistors, relays, we have solar panels at work too, I can mock up a configuration and then hash out a clean install later. We even have a heat gun i can test for a thermal sensor.

 

I need a good roof rail solution, something nice and permanent as I do have a roof basket I would like to use maybe in the future.

 

The V has a different part number between the brand 4 seasons. But the others its the same part between the V and a regular prius both 2015 years.

Unless the images are reversed, the fans according to photos and part numbers are different. Gonna have to do an OEM part search. I did discover that the AC blower motor IS different because it says so in the part descriptions one for thise with the solar roof option and those without....and so the plot thickens.

 

Another interesting discovery, the blower motor for the solar roof option uses twice the amount of power, Nissens brand differs them 30 and 17 amps. I wonder if it puts out more CFM? More powerful HVAC capabilities? I could switch out the fuse and def have to check the wire gauge in the harness to make sure its capable of handling the current. I may ho deeper in the hole and pull up a wiring diagram to see if the solar vent control module can be used (unlikely). At this point of knowledge I would use the solar power to run the blower motor which should theoretically push air in from outside and out the rear cabin exits, hence the more powerful motor, that may be the best way to do this without getting complicated. The solar option fan is twice the cost new ill find a used one, if not ill just pay the $140.

Solar controller will be needed, MPPT, ill have to find a way of designing a variable fan speed PWM controller behind a diode so current doesnt flow the other way when the engine is running normally as well as an ignition switch to cut it off.

It may be that I design this to not use a battery at all for stored energy, If I were to utilize the 12V Battery system in the car I would use a low voltage disconnect on the fan so I dont end up with a dead 12V battery, probably set it kinda high too, prevent the depth of discharge from going anywhere near to the point of not starting the car. But the solar panel charging the 12V battery has its own risks.

This brings me to my next point, the fan would use at most 30 amps....I would need more panel space in solar panels than the cars surface area would allow, hence the need for an MPPT to maximize current harvesting. Its unlikely ill ever be able to run the fan at max speed. This reopens my thoughts on utilizing a second battery to pick up the amperage when needed. A whole lot of thinking and revisions... reinventing the wheel so to speak.

 

I need a high density quality panel for power, ive seen some that collect residual light on the underside from the casted shade.

 

Im assuming you were referring to the blower motors for the HVAC and not the battery

 

This is the panel I want. 15A at best should flow enough to drop the temps.