Carry Solar or More Battery for touring?

[mvly]

Let say I am carrying solar kit which is 300W panels with converter which charges the pack during the day. This 300W panels weighs around 25lbs with the converters and wires and such.

What is the alternative? I can carry 25lbs worth of battery. This should be at least 1KWh extra if I do carry a lithium battery pack.

If I get roughly 12+ hours of light in the summer with the inefficiency and dawn and dusk calculation, I think you can realistically get 5-6 hours of perfect sunlight. This is 300W*5hours = 1.5KWh of energy recovered. If you factor in cloud and imperfect panel angle, then you should at least 1KWh out of this solar setup.

So what are the pros of carrying solar?
You don't have to "charge" as much overnight. If you are indeed touring and stopping at hotels or RV parks, it might not matter much. However if you have a large enough pack, you might not be able to charge completely overnight. The solar kit can allow you to "charge" as you go. If you have a 1KW charger, and you plan to spend 6-7 hours charging, then that will give you realistically 6KWh with balancing time factored in. I am using 1KW charging because you don't trip some circuit breaker here in the USA.

Cons?
Yes, the setup will cost much more than just having battery. And the setup is going to be more complicated.

Worth the cost? Probably not if you are after the cheapest setup for touring. But if you want to go the max distance, then it might make sense. Also as solar technology gets more efficient, maybe you can get more back from the sun. But then again batteries will also get better too.

 

[Schlafmutze]

Pros, freedom of being able to charge anywhere you want really, no dependency to a socket.

Cons, generally heavier, a bit more hassle to set up, and expensive, though you can get really thin, efficient, light panels

just my 0.0119091924 British pounds.

 

[mvly]

Pros, freedom of being able to charge anywhere you want really, no dependency to a socket.

Cons, generally heavier, a bit more hassle to set up, and expensive, though you can get really thin, efficient, light panels

just my 0.0119091924 British pounds.

I wouldn't say no dependency on a socket. I think you still need to charge. It just meant as a supplement to your battery. I don't plan to wait days just to fully charge my battery via solar.

I think when I say 300W for 25lbs. I think that is best you can get. Maybe you can shave 5lbs off the 25lbs but it's already using the sun power 22% efficient cells that is water proof and curved with a small MPTT solar boost charger. So that is currently the limit of the technology available to the general public.

Am I missing anything other pros and cons?

 

[motomech]

Well, you have made almost 1000 posts without filling out your profile, but if you are going to ask about the viability of solar, you might at least let us know where you are.

 

[dogman dan]

300w for 25 pounds? Really? If so , there went the biggest reason not to. I thought it would be more like 50 pounds or more, at which point a generator may be lighter.

But you will have to do all your riding at night or at least not at noon.

OR you have a really big flat trailer, and can tilt that panel any direction, and don't have to tilt it backwards. Ride north or south, if east or west, you have to tilt the panel the wrong way half the day. Or leave it flat and get less watts.

You won't get 12 hours of max insolation, so do your math based on 6 hours max, and that's only if you live in the Desert SW USA. Many places, it's more like 3-4 hours average. More in summer of course. but still not 12 hours of full output.

My personal choice has been mo battery. I carry as much as 35 pounds of battery. Some pretty bad, so about 48v 35 ah of real world usable capacity. Once I ride that flat, I desperately want to stop, and will be back into a town.

Just carry 2000 wh, and you should have plenty.

 

[oldwahoo54]

The Elf only has a 100W panel, and they claim 7 hour re-charge time for 11 Ah. That's probably assuming you park the thing in a somewhat optimal direction wrt to the sun.

http://organictransit.com/features/

 

[mvly]

@dogman,
Glad we are coming up with similar numbers. Point is I think you can get 1KWh out of the 300W panels riding 12 hours or more during summer days. Yes I have factored in all the inefficiencies.

I can assure I can get 300W panels under 25lbs. Maybe even under 20lbs with all the wirings. Technology have progressed quite a bit.
panels are HERE:
http://www.ebay.com/itm/Semi-Flexible-150-Watt-Solar-Panel-High-Efficiency-Sunpower-Marine-Rated-/141301845676?pt=CPUs&hash=item20e63f0eac

get 2

MPPT boost charger are HERE:
http://genasun.com/all-products/solar-charge-controllers/for-lithium/gvb-8a-li-lithium-solar-boost-controller/

If you look at the panels and charger only. It's albs + 7lbs + 0.5lbs = 14.5lbs. If you factor in wiring, you can around 15lbs +/- albs.

Cost is around 1K ($345 x 2 + ~300) = $990.

@oldwahoo54,
At what voltage? I think they are using 48V battery. 48*11Ah = 528Wh. So yeah under ideal condition, it should only take 7 hours. But I think you will need a full day before that battery is full.

 

[dogman dan]

That's a badass panel, the specs look pretty legit to me. Price can be tolerated too.

This should have come a lot sooner, but finally it's here. This is the first solar panel I've seen really worth packing on a bike trailer. Thin film just had to be too big, panels for houses just too heavy.

A tad awkward in dimensions, make your trailer 9 feet long, or 4' 2" wide? Damn sure not a bad idea to carry 150w, That's more bike trailer size. You can go a long ways with a charged battery, and 150w of combined pedaling and solar. Draw only 100w from the 1000wh pack for 10 hours. 250w is plenty if you are riding a long flat road.

I still tend to prefer just carry a lot of battery, since I have it now after all. But I can't ride to a place with no plug that way.

At 7 pounds per panel carrying 300w to deploy when stopped looks good. 450w of panel will crank out some serious charge from 10 am to 2 pm. Then run 150w while rolling?

 

[jimw1960]

Two of those ebay panels you linked to will have a 20 square foot surface area. You'd have to tow around a pretty big trailer to make that work.

 

[arkmundi]

I went to the http://cse.fraunhofer.org/ grand opening in Boston Wednesday, on my eBike and on it into the auditorium. Hahhaa, no really - I do have a gimp leg from polio and its part of the reason I'm on an eBike. So Fraunhofer does solar panel testing. Lot's a very sophisticated equipment and other stuff of interest. These are one of the few R&D shops in the world on the cutting edge for improving solar. I got to talk to lots of experts in the field. Answer to the first question: what is the best solar panel I can buy on the market today? The SunPower panels, which can deliver ~21% of solar radiation. Answer to second questions: will it be getting better than that or are we at the extreme of what is physically possible? We're at the extreme >21% is unlikely. Maybe approaching 22%. The competition is on for lowering costs and that will continue to improve. Answer to question three: how about solar focusing for mobility, cars & such? Yes, this is a very active area of research and we'll be seeing a lot of new tech coming out. And yes, those solar focusing devices for the rooftop of cars is emerging and really great. Have an eBike - that would be the thing to do.

 

[motomech]

Pannon Rider – Solar-powered bike saves you from harsh weather

http://www.ecofriend.com/eco-bikes-pannon-rider-solar-powered-bike-saves-you-from-harsh-weather.html

 

[motomech]

I live in Tucson and I believe that 9 or 10 months a year, a rig like this one would allow 10 or 12 hr.s a day @ net 0 battery deplition. 15 mph.
But could one deal with the heat and only out in the boonies would I not worry about being mowed over by some idiot racing to Vegas.
Still, I'm thinking pretty hard on building a copy of the Pannon Rider.

 

[mvly]

Two of those ebay panels you linked to will have a 20 square foot surface area. You'd have to tow around a pretty big trailer to make that work.

If you have a recumbent trike. One can go on the canopy and the other on top of the trailer.

@motomech

I am not sure you can expect a constant 300W from these. I suspect it will be closer to around 240W max or even less if you don't have the right angle. I say expect a solid 140W from the 2 150W panels. This might be enough to use 0 battery power if you assist it quite a bit and go slow enough. But at that point why not just lighten the weight and get a regular bike to pedal.

I say keep these panels as a way to extend your range. Don't try to use them as solely the power source to power your bike. We need around 80% efficiency panels before we can safely replace the majority of the battery with panels and not have to pedal. But sadly we are only around 20% now.

 

[RLT]

There is this:
http://www.youtube.com/watch?v=pPt2Qcf4Ds8

I'd sure like to know some of the technical details.

Got a bunch of spare 235 watt panels laying around: I'd try building something similar (except with batteries), but I'd worry that even with the panel horizontal, I'd be blown up, down or over by the wind, or a passing semi.

 

[mvly]

There is this:
http://www.youtube.com/watch?v=pPt2Qcf4Ds8

I'd sure like to know some of the technical details.

Got a bunch of spare 235 watt panels laying around: I'd try building something similar (except with batteries), but I'd worry that even with the panel horizontal, I'd be blown up, down or over by the wind, or a passing semi.

If you watch to the end, he did say 220W panels and some motor and probably a 24V or 12V brushless controller. It might be a 24V controller because that is more common. Panels might be a 36V panels but under load I suspect it is somewhere around 24V and providing just enough juice to the motor to make it run at < 25kmph under full sunlight which is pretty slow IMO, though he did not need to pedal at all.

Though he did do it in the desert which have ample sun and mostly flat terrain. I suspect if he did it on terrains with hills or cloudy days, I doubt he can do what he did without pedal assist. Also the desert sun is probably the best in terms of power generation. I think it can be done better now with the panels I recommended and the charger I pointed with a small battery to use as a buffer for those cloudy parts.

 

[encore8899]

Pannon Rider – Solar-powered bike saves you from harsh weather

http://www.ecofriend.com/eco-bikes-pannon-rider-solar-powered-bike-saves-you-from-harsh-weather.html

Those solar panels are standard alum frame. Must be around70-80lbs!! Looks front heavy.

I just joined this group recently and have been reading for a while. Lots of knowledge here! This is my first post so don't flame me yet..! haha =)
Anyways, I'm pretty much planning to do the same thing, except use those new lightweight solar panels. I think it will be a game changer cuz light panels will make everything else lighter. Initially I'm gonna try 2 100watt panels side by side longitudinal. They will stick out about 6inches on each side of my trike but should be okay. They are roughly 41"long and 21" wide. If that's not enough I will add a third panel in the back if room permits. I believe 200-300 watts should be enough using an mppt controller and light throttle on an efficient mid drive. Should be able to double range with moderate pedal assist and throttle only on hills. I'm looking at the genasun mppt controller or something comparable. Unfortunately their controller only spits out 8amps, but at 48v that's still near 400watts of recharge in full sun. I'm in process of making my new catrike expedition as light as possible. :lol: The only thing I'm trying to figure out is the battery. I'm planning to use lipo to save weight. 14S seems like the logical battery for their claimed float voltage of 56.8V. That equates to 4.05V/cell. I wish I could go 12S and save money... but the voltage doesn't work out. I just can't get myself to spend that much on a charge controller. Ridiculous.

 

[Sunder]

I'm a bit late to this thread, but I was thinking at 25lbs, you're getting close to the weight of a small generator.

Here's a 1000va generator that only weighs 29lbs http://powerequipment.honda.com.au/Super_Quiet/EU10i

If you were brave and didn't need a very reliable long lasting solution, you probably could build your own generator out of like a 10cc monkey bike or RC motor for half the weight, and just charge overnight. (If noise wasn't an issue)

 

[encore8899]

What's the point of riding a bike if you're gonna use a generator??!! Might as well ride a motorcycle!

 

[dogman dan]

My ancient Honda 700w generator weighs about 75 pounds. 29 pounds would nearly be tolerable. I'd still like to see a 400w generator in the 20 pounds range. That would work with trikes or other cargo bikes. 400w continuous would give you serious range, but ideally you'd still do as much of the actual riding with the damn thing turned off.

The way I use mine is not to carry it on the bike, but take it and the bike to a campsite, then do a lot of riding. Not pure, but It gets me a plug and I don't have to stay in the towns. While it runs, I put it far enough away from my camp to not drive me nuts. I can also charge while driving to the next riding location since I carry bikes on a trailer.

If I was made of money though, I'd be real interested in making my trailer a solar trailer. One that would charge one battery while I was out riding in the woods on another. Use it at home too of course.

 

[Sunder]

My ancient Honda 700w generator weighs about 75 pounds. 29 pounds would nearly be tolerable. I'd still like to see a 400w generator in the 20 pounds range. That would work with trikes or other cargo bikes. 400w continuous would give you serious range, but ideally you'd still do as much of the actual riding with the damn thing turned off.

The way I use mine is not to carry it on the bike, but take it and the bike to a campsite, then do a lot of riding. Not pure, but It gets me a plug and I don't have to stay in the towns. While it runs, I put it far enough away from my camp to not drive me nuts. I can also charge while driving to the next riding location since I carry bikes on a trailer.

If I was made of money though, I'd be real interested in making my trailer a solar trailer. One that would charge one battery while I was out riding in the woods on another. Use it at home too of course.

My experience is that with solar, you never quite get what you pay for. Those 200w panels only get 200w for an hour or two a day - and then only if it's angled right and it's kept below 25*.

Great solar is coming. Hell, it's already here, if you want to pay through the nose for the 50%+ efficiency panels (I guess you did say if you were made of money, but then it could literally cost you an arm and a leg!). But the common 12-15% efficiency panels are just too bulky and inefficient to haul around.

Fuel cells would be the other interesting but not practical one. You can carry a lot of energy in 1kg of propane, and it runs silent, unlike a generator. The price of a 1kw fuel cell however, you could probably buy a small car.