Quote:
Originally Posted by MetroMPG
(Post 47535)
For this approach to make sense financially, you would neither either (or both) of:
1) fuel that is much more expensive than it is now;
2) a supply of free or cheap batteries.
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You forgot 3) A source of cheaper electrical power.
That's why I think that solar cells are so interesting. Because after you've spent the initial $$$ for them, good solar cells will usually last longer than most cars (so they aren't a "consumable" per se, more of a "durable good"). In fact, in many areas, solar can already "pay for itself" when compared to "grid power" in the home (it takes several years to get to "break even", but in many areas you do eventually get enough power savings to pay for your initial investment, after which everything is "money in our pocket"). And since the standard sources of electricity in the car are much more expensive than "grid power" for the home, solar for the car should be even more "cost effective" (i.e. theoretically have even a shorter time period for "break even").
Now I don't think that solar is the whole answer in a car. I just think that some carefully chosen (and carefully installed/mounted) solar panels might be "worth it" from a cost/benefit standpoint given a long enough time horizon. In other words, think of solar as a "durable good" type mod. A few hundred $$$ solar panel likely won't save a lot of gas, but (as long as you don't kill that savings by worse aerodynamics and/or the weight of the solar panels) it will likely start saving you a small amount of fuel (by lowering the need for power from the alternator). And eventually (after a few years), you will likely have reached "break even" (saved enough fuel to pay for the solar panels), after which all the extra fuel savings is just "money in your pocket". At least that's what I think my initial "playing with the numbers" seems to be telling me about solar panel power generation in cars.
NOTE:
There are only so many places that "make sense" to mount solar panels in cars (and those mounting spots vary with the car design). So there is a limit as to how much solar power you can get in a car (even if you had an unlimited budget to buy additional solar panels), and that limit varies with the car design (with some "vans" and other big vehicles, having a lot of room for cell mounting, and some small cars having virtually no room for solar cells). This doesn't mean it's not worthwhile to use solar (as any solar power should lower gas needed to otherwise generate that electricity), just that these limits may prevent you from solving all of your car's electrical needs via solar.
For example, the most logical place to mount the panels in my CRX, would likely be under my rear hatch window, but on top of the the internal "trunk cover" that's below that hatch. This would make the panels easy to mount, and also avoid the aerodynamic issues (as the panels would be fully within the cabin of the car). However, it also puts a pretty hard limit on how much panel space I could use, as there is only a few square feet in that area (enough for a small solar panel or two, but that's it)! And while those numbers are unique to my car design (other car designs would either have less or more space for panel mounting), every vehicle on the road will have limits in this area, as no vehicle has "unlimited surface area". And once you've reached your limit in solar panel surface area, pretty much the only way to increase your solar power, is to use more costly/efficient solar cells (and thereby get more power for each square foot of solar panel space) and/or better battery/charing circuitry (to better store the solar power still being generated when your car is turned off), and even those efficiency and storage technologies also have their limits. So eventually you will reach the limits of what you can do with solar inside a car no matter what you do.
But just because solar has limits in a car, shouldn't be a reason not to use solar at all. Because, until you reach those limits, solar could still easily "help" more than it "hurts"!