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Discussion Starter #1
I don't know much about solar, electricity, HVAC, etc. Much discussion has been made here of solar powered fans cooling the car during the summer. This gave me the idea to ask a corollary question ...

Could a solar powered system be used to HEAT the car during the winter?

Obviously, the amount of heat generated would not be all that significant, but even keeping the car a bit warmer in extreme cold sounds desirable to me. (Both while driving and parked)

Thought the amount of heat generated would be very small, every little bit would help. If it could impact the interior temp of the car by 1 degree, would it be helpful while driving by not having to extract as much heat from the engine (which I have read is quite a problem in very cold weather, auto-stop, etc.). It might be like setting the climate control system thermostat to 60 while only extracting heat from the engine as if it were set to 59?

Likewise, a bit of warmth added to a parked car for long periods of time would be nice. Perhaps this would be the best benefit of solar powered heaters.

I plan to do the solar colling fan system using Uni-Solar FLX-11 (I think), and was wondering if this investment could have a dual purpose of a bit of extra heat in winter cold.
 

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Putting a mat black mat in the hatch area would work. Insulating the car body would help. Blocking the rad and using a hot air intake help. A dark paint job helps too. Some cars including the new Prius store warmth from the engine in a thermos bottle. The good thing about heat in the winter is that all of it is derived as a waste by product of engine operation.
 

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Right, passive solar heating is the most bang for the buck in this case. b1shmu63's suggestions are very good. I don't believe anything more complex would be reasonable for this application, but hey, how much money do you want to spend?

I have reflective tinting on my windows, which reject heat pretty well. I wonder if there is the reverse available for solar? Probably. Sure would be hot now, though...
 

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Solar power would work by converting the incident solar energy (mostly visible) into heat. Unfortunately, solar power is quite inefficient, on the order of 10%-20% just to gather the incident light and convert it to electricity. Also, cold days have a much lower incidient solar radiation at the earth surface, which is a big part of why they are cold days, and not hot days. And if it's cloudy, you can forget about it.
 

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Discussion Starter #5
If the solar panel is there, any benefit to use it?

Thanks for all the great info.

I guess my question remains this ... since I am going to have the solar panels in the car anyway (from the summer cooling fans), could I expect any beneficial result from disconnecting the cord from the fans, and attaching it to a (obviously) very small heating element (trivial cost)?
 

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Well, might as well, eh? It surely won't hurt.

I just imagine that the contribution from photovoltaic resistance heating would be miniscule in the big picture....
 

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Discussion Starter #7
Holicow said:
Well, might as well, eh? It surely won't hurt.

I just imagine that the contribution from photovoltaic resistance heating would be miniscule in the big picture....
Thanks Holicow ... That answer really provided what I was looking for ... "miniscule". Perhaps once the solar panel is in place, I will connect it to an auto cigarette lighter, and see (probalbly not see, but rather feel!) what hapens!
 
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Hi DonWatson:

___If you drive during midday in late fall/winter/early spring, you can go coatless all the way down to the about the low 40’s just with the heat load generated from the rear hatch’s window. This is on a bright and sunny day. Below that, it’s a light jacket down into the low 30s, heavier jacket and light gloves in the 20’s … in the teen’s, on goes a hat and below that, you will have the life (mpg’s) sucked out of her as you turn on the heat. At least it’s can be warm and cozy while cruising down the freeway.

___As for the cigarette lighter resistance heater, forget about that one. The draw from the 12 V - off the pack - off the MGSet will be far more then just pulling the heat from the ICE’s coolant as its mostly waste heat anyway … unless that is you are really pushing the fuel economy envelope, then its lifeblood ;)

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:39kg3mtb][email protected][/email:39kg3mtb]
 

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Well, now...

What an intriguing question...

We have one of those "coolers" (to me, a cooler is a plastic box with a lid, where I put ice and sodas for adult beverages and perishable food; these newfangled things I'm referring to are some sort of punky refrigerator) that plug in to the cigarette lighter in our travel vehicle (the "Big *** Van"). They work on some sort of thermoelectric voodoo that converts 12v into cooler temperatures without the bother of coils, freon, or whatever chemicalia exists in our real 'fridge. It does have a pitiful little fan which makes more noise than moves air IMHO. But it does work. :shock:

Now... You can also reverse the polarity of the cable, which then provides... heat! Enough to heat the contents of the "cooler" (now a "heater") to the borderline-lethal-to-bacteria level of 145 degrees. :twisted:

This miracle happens with 12v, and manages to heat approximately (guessing here, eyeballing it) 1.5 to 2.0 cu. feet of "cooler" (I mean, "heater") -enclosed mass to 145 degrees within a pretty short interval of time. Surely the coolers are not that pricey, especially if a lucky garage used-"cooler" sale buy is possible now that summertime is on the wane. May I humbly suggest the sacrificing of one of these gadgets, to see if the innards may be used for whatever minuscule amount of heat may be created thereby? :wink:
 

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Those coolers you are reffering to use peltier devices to heat or cool. Basically you pass DC electricity through it one way it pulls heat to one side, reverse it and it pulls it to the other side. It can only get so cold or so hot, something like 40 degrees of ambient either way. I've tried one in a vehicle here and the result durring the summer was only marginally cool water bottles after a few hours.

I was browsing around a few weeks ago looking at some EV conversions and saw one where the owner had made a large peltier array for cooling and heating which he said worked quite well. There were no pictures or anything beyond the description unfortunately. This idea has been on my mind as of late, the question is would a peltier array fed by the IMA motor be more efficient than the AC compressor turned by a belt from the engine? You could at least have auto stop with cool air. BTW, you can buy peltiers in bulk fairly cheaply.
 

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All the solar radiation that enters the car and is not reflected back out of the car is converted into heat. If you want to reflect less energy, paint the interior flat black. Using a black piece of posterboard would have the same effect as using a photovoltaic panel of the same size, and heating a resistor. It might cost less though :D
 

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Thanks, Rick

I figured someone here would know more about this than I. Cheap peltiers! Compressor-less a/c! Instant heat without warming up water! Pure magic. Next thing you know, we'll be communicating without wires... :lol:
 

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Discussion Starter #13
Does a cooling peltiers eject heat?

I have seen such devices built into coolers at department stores. When running in cooling mode, isn't there a fan on the cooler ejecting heat from the cooler? (If so, how would we eject it from the car?).

If it is a heat/cooling exchange, the heat/cooling generated would be offset by the heat/cooling discharged (if not ejected from car).
 

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Re: Does a cooling peltiers eject heat?

DonWatson3558 said:
I have seen such devices built into coolers at department stores. When running in cooling mode, isn't there a fan on the cooler ejecting heat from the cooler? ....
Aha!

Well, you could just roll it up in the window, and duct-tape whatever space is left, right?
 

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I don't believe the Peltier coolers are all that efficient, else they'd be used a lot more :) Instead, they provide cooling where a conventional refrigeration system won't fit, like portable ice boxes, CPU coolers, etc.

I think the solar heated Insight might really be an insulation problem. After all, as people have said, it does capture a lot of heat. Problem is, aluminum is not really noted for its effectiveness as an insulator :)
 

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Solar electric preheating of the engine could be done thusly. Use a stainless thermos to store 3 litres (three quarts) of the engine antifreeze mix. Place a 15 watt resistive heater in the themos with a 200 degree cut off switch. Connect this to 15 watts worth of solar panels. use an elecric in line pump to circulate the fluid through the engine on startup. :D
 

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Discussion Starter #17
That sound like a lot of heat!

b1shmu63 said:
Solar electric preheating of the engine could be done ... Place a 15 watt resistive heater in the themos with a 200 degree cut off switch. Connect this to 15 watts worth of solar panels. :D
The mod you describe sounds fantastic, but I have just had this puppy for about 3 weeks, and will keep this in mind for the future!

Last winter, here in Boston, we had a 2 week period that stayed around minus 10 to minus 5, never getting above 0. My car sits all week long (as I take the train to work), and I would like to have a way to keep it warmer as it sits. Plan to get a black rubber mat for the back as others have suggested.

However, the amount of heat you are descriving -- heating this much water up to a potential temp of 200 -- all on a 15 watt solar panel does NOT yield an insignificant amount of heat!

Any advice on what type of small (simple?) heater I could place in the center of the cargo area that would be best to hook to the 15w panel, and keep the interior warmer during extended extreme cold? After reading many posts, I am a bit concerned about the batteries being kept so cold and only being used on weekends.
 

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To elaborate a little, both VW and Prius use this kind of remal recycling technique. The fluid is heated while the engine is running and the thermos keeps the fluid warm for a couple of days. In the case of the Prius the water is circulated into the engine by a small electric pump before the car starts. (if it did not make a difference then Toyota would not have gone to the trouble of including it in the new Prius.) What I'm suggesting is that the small amount of energy, 10 to 15 Watts, added over a period of a few hours would replenish the heat lost by the thermos during those two days. That way the fluid would be kept piping hot. To get an idea of the amount of heat, take a 7 Watt or 15 Watt candelabra type bulb and hold it in your closed hand. Plug it in and I guarantee you'll get a warm feeling, just don't blame me if you burn yourself. Now 10 or 15 Watts should be feasable to collect from solar panels. The panels have a nice dark surface so whatever percentage of energy is not turned to electricity by the panel will be turned to heat inside your car anyway. The beaty of the electric heater is that only an infinitesimal amount of heat will be conducted out of the thermos by the connecting wires which will only have to conduct 1 amp and therefore should be really thin. A fifteen ohm 15 Watt resistor or a suitable length of Nichrome wire would suffice for the heating element. This however is a real labour of love type project as it would take quite a few hours to do it up right. I already bought a couple of 1.5 litre SS thermos bottles for this kind of a project but like yourself it I'm waiting to get a "Round Tewwit". :D
 
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