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Raising a bumper crop of electrons?
Until now, acreage was designated for either photovoltaics or photosynthesis, that is, to generate electricity or grow crops. An agrophotovoltaics (APV) pilot project near Lake Constance, however, has now demonstrated that both uses are compatible. Dual use of land is resource efficient, reduces competition for land and additionally opens up a new source of income for farmers. For one year, the largest APV system in Germany is being tested on the Demeter farm cooperative Heggelbach. In the demonstration project led by the Fraunhofer Institute for Solar Energy Systems ISE, solar modules for electricity production are installed directly above crops covering an area of one third hectare. Now the first solar harvest of power and produce has been collected on both levels.
"The project results from the first year are a complete success: The agrophotovoltaic system proved suitable for the practice and costs as much as a small solar roof system. The crop production is sufficiently high and can be profitably sold on the market," explains Stephan Schindele, project manager of agrophotovoltaics at Fraunhofer ISE.
Why not cover parking lots with solar panels instead? Parked cars do not need to perform photosynthesis.
(Score: 2) by choose another one on Wednesday November 29 2017, @01:48PM (13 children)
For both parts of the quote, kinda. Parked cars do not need to do photosynthesis, but may need to do photovoltaics:
https://www.just-auto.com/analysis/manufacturers-energise-the-solar-car-roof-market_id177587.aspx [just-auto.com]
(Score: 2) by Immerman on Wednesday November 29 2017, @03:43PM (2 children)
Photovoltaics on a car are only just barely viable - a car 100% covered in solar panels that spends all day in direct sunlight, will get you enough charge to travel 10-20 miles. Sounds like the Prius mentioned at the top gets all of 3 miles of range extension.
Basically, for probably 95% of the population it's nothing but a sales gimmick, and you'd be much better off parking in a solar-roofed carpark where the panels are properly oriented for high solar gain.
(Score: 2) by VLM on Wednesday November 29 2017, @07:57PM (1 child)
I'll trust your numbers, whatever. Thats still enough miles for a large fraction of many peoples commutes, lots of gas or coal not being burned.
There are interesting side ideas. For many years I've been planning in my infinite spare time to rig up a solar panel to HVAC, so my car is a bit warmer in the summer and a bit cooler in the winter. Also supposedly float charging a battery is better for it than letting the security system run down. And I could use an electric pump to keep the oil filtered (boaters "polish" their diesel this way) and I could even dump a couple watts into the battery and block heaters (I live up north). Maybe two hundred watts of solar would really improve my car owning experience and doesn't cost that much compared to trying to go hybrid electric.
One of my coworkers came up with an interesting figure of merit for weight of car accessories like these solar panels... based on current obesity increase rates, yes a panel weighs a couple pounds, but its merely like having a fatter driver from 2040 drive today...
(Score: 2) by Immerman on Wednesday November 29 2017, @08:59PM
Heck, 10-20 miles would do me pretty well too. The problem is it's all but impossible to reach even those numbers in any sort of cost-effective manner. The Prius's 3 miles from a roof-mounted panel is a lot more realistic.
The problem is that it's difficult and expensive to make them conform to the curved surfaces of a car. even flexible panels can only curve in one direction - i.e. they can curve around a cylinder, but not a sphere. And getting rid of bidirectional curves is going to cost you a lot more in efficiency than you gain in power. So that means lots of small panels instead, which increases manufacturing costs considerably. You also need more sophisticated (and expensive) power regulation since those panels will all be facing different directions and thus producing different amounts of power.
And then you'd have to always park in the sun to get any benefit - and in the summer that probably means using even more power to cool off your otherwise broiling cabin.
It just makes a lot more sense to put the solar panels in places and orientations that are good for generating power, and then charging your car from those. Unless you're planning a very slow survey of someplace very remote, where you plan to average only a few miles per day across territory where fuel or electricity may be impossible to find.
(Score: 2) by Grishnakh on Wednesday November 29 2017, @04:19PM (8 children)
No, they don't need PVs on cars. PVs on cars is an utterly stupid idea. There simply isn't enough area on top of a car for a decent number of PV cells, and with the shape of cars, most aren't going to be oriented in an optimal direction. Worse, PVs are somewhat delicate and aren't that great for outer body panels. There's just no way you're going to generate enough energy with these things to extend an EV's range by much.
The other poster is correct: if you want to power EVs with solar panels, cover the parking lot with them and use that to recharge the cars underneath. (Or, more sensibly, don't discriminate: put the roof-generated PV power on the grid for a profit, and then have the EV owners get their energy from the same grid and pay the going rate, which will be low due to all the PV panels covering parking lots. Then if the lot is mostly empty, the energy can be used for running HVACs or be stored or used in all the other ways we use electricity.)
(Score: 0) by Anonymous Coward on Wednesday November 29 2017, @08:53PM (1 child)
Taking another poster's number of 10 to 20 miles... yeah, that'd do. My car is always outside in Florida, totally unshaded.
My commute is a mile. The store is 3 miles away, and church is 4 miles away.
Assuming 2 grocery trips, that is 30 miles per week. I'm allowed 70 to 140, so I'm well within the limit.
Obviously, the trick is to have a sane commute. This is the norm in moderate-sized cities and towns across the USA. If are a typical Californian, commuting from Davis to San Francisco or from San Marcos to Los Angeles, then this isn't going to work. Fix your lifestyle.
(Score: 2) by Immerman on Wednesday November 29 2017, @09:04PM
The real trick is covering your car 100% with solar panels (windows included) to get that kind of range, and then always parking in full direct sunlight. Like I said above, 10-20 miles is the best-case scenario in a very expensive concept car. 3 miles is more realistic.
(Score: 0) by Anonymous Coward on Wednesday November 29 2017, @08:56PM (5 children)
When you get back from a long trip, you may find your car battery dead. The doors won't unlock normally. You can't roll down the windows. The radio settings are gone. The transmission has lost memory too, so shifting will be rough.
When you park in the Sun, the car gets hot. You can't have a fan running because that would run down the battery.
(Score: 2) by Immerman on Wednesday November 29 2017, @09:12PM (4 children)
That's no job for a solar powered car though, that's just a trickle charger to counteract self-discharge. You can get them for like $50 that sit on the dash and plug into you lighter socket. For a couple hundred manufacturers could integrate it into the roof, which may well be a nice idea.
Solar fans also make great sense - when solar heating is a problem, solar power is also available.
Neither has anything to do with powering the *car* though.
(Score: 2) by urza9814 on Thursday November 30 2017, @05:45PM (3 children)
I've been wanting to get one of those -- after having gotten stranded with a dead battery more than once. Particularly since every time my battery dies I get it tested and the tests say it's in perfect shape. Automotive electrical systems are garbage. It should not be that hard to tell if a battery is going bad; and for something so critical there should be some kind of backup mechanism that'll at least let you start it once so you can drive to the auto parts shop to get a new battery. Hell, they've got capacitors big enough to start a car, so slap a few of those in and only use the battery to keep them topped up if the car is sitting for a few days! Although I'm also looking at the solar panel hoping I can get enough power to run a Pi or something...looking at one that's advertised as "40W" so if it manages to peak at 20W that'll probably be plenty, I think the Pi uses less than 5...
Problem is cars are going electric, which means no starter battery required. So while that would be a great use for installing solar panels, it's a bit late now! If I wanted to get built-in solar panels on my next car, they'd probably have to be building the things already; and the one after that I expect will be electric...there's a small and narrowing window during which that would actually be useful. Aftermarket it cool though, especially since you can just move it to your next car if that's still ICE (or use it for something else entirely!)
(Score: 2) by Immerman on Friday December 01 2017, @05:00AM (2 children)
Have you checked the wiring? If the battery tests good but keeps going dead, then you may well have a short in the system somewhere. I had a car that would come up dead at the most inopportune times because of that.
Disconnecting the negative terminal and re-linking the circuit through an ammeter will help isolate it - if you're drawing more than a handful of milliamps when turned off then just start pulling fuses until you notice the current drop. That'll tell you which set of systems have a problem, and if there's nothing important on the circuit you can even get away with just leaving the fuse pulled to until you feel inspired to try to root out the core problem. Assuming you have an ammeter and a friend to monitor it, 15 minutes of effort may be able to at least corral your gremlin. I never did figure out exactly what was causing my problem, but that car ran fine for years without some auxilliary features I never used anyway.
(Score: 2) by urza9814 on Friday December 01 2017, @04:08PM (1 child)
No, the first time I got it tested and trusted those results and it died several more times before I finally replaced the battery, then it was fine for four or five years...the next time I had it in the shop for a check engine light, so they ran a full diagnostic when they were done which included a battery test that said it was good and two weeks later I started having trouble starting it so I replaced the battery and it's again been fine ever since. It's not like I replaced it and the new one immediately died too...What I suspect might happen is the capacity gets low but the maximum voltage is still high enough so that if I drive it to the auto shop it's freshly charged from driving there and therefore tests fine, but the capacity gets low enough that the security system alone can run it down to the point that it won't start if it sits for a few hours. Might be something there using more power than it should but it can't be a huge amount...I'm getting about the lifetime you'd expect from the batteries, it's just that when they do go bad it seems to be totally unpredictable. My laptop can tell me to the minute when the battery is going to die and can pick up on any loss of capacity over time; but something as big and expensive as a car seemingly can't manage that even with specialized diagnostic tools!
I mean obviously things fail, but that seems like such a terrible failure mode. Maybe it's because I'm more into electronics than mechanics, but also I think it's just because I've seen so many far less expected failures leave cars completely driveable. I mean you can blow a tire on a pothole, your break lines can rust through, the transmission linkage can fail, the radiator can spring a leak...all pretty serious issues that you really shouldn't drive with, but all those could happen at once and you potentially *could* still drive the thing if you really had to. Yet if I can't source a lousy ten watts -- in a world where I can walk down the street with a couple hundred in my freakin pockets -- you're just stuck.
(Score: 2) by Immerman on Friday December 01 2017, @09:06PM
That sounds reasonable - 5 years is a decent run for a battery.
As for your laptop battery, it has built-in electronics that monitor its charging profile over time - and even then its predictions can get pretty bad near end-of-life My last one would still hold a half-hour charge or so, but would go from 20% to 0 in about 30 seconds.
I will say I much prefer a car with a battery gauge on the dash - no "idiot light" that rarely tells you much until the problem is already obvious, but an actual voltage gauge so I can tell how the voltage is doing in the morning before I start it up. A little bluetooth OBD-II dongle is incredibly useful for diagnostics, but I'm just not going to have that set up on a regular basis.
(Score: 2) by EvilSS on Wednesday November 29 2017, @07:09PM