My solar bike

avandalen

avandalen

100 W
Joined
Oct 2, 2010
Messages
175
Location
Maastricht, The Netherlands
The goal of this project is making a solarbike that at sunny summer days receives enough solar power to allow cycling longer distances and cycling hills with sufficient assistance. Instead of the common ebikes, which are heavy, de solarbike must be lightweight and sportive. It may not cost substantially more energy to drive the solarbike, when not powered, than a normal bike. When there is no sunlight or the batteries are empty the bike should still be light running.
See my website here for the complete text:

http://www.avdweb.nl/

Solar-bike.jpg
 
Hi,
Even if the manufacturer claim 21% efficiency you won't get more than 17% in the best case (with Mppt and at lunch time in the summer).
I'm curious to know how much surface are you aiming ton mount on your bike? I have a 120W mono-crystalline panel (with "only" 16% efficiency) at home and it weights already something like 10Kg for about 1m².
it will deliver 120W max in the summer with full mppt control and manual orientation of the panel to get it 90° with the sun (at lunch time again ;) ).
100w on an ebike won't be sufficient to reach 25-30Km/h that's the good point :) you won't get problems with the police :).
grüß,
H.
 
Dear dodjob,

In the mean time I have finished the solar panel article on http://www.avdweb.nl.

The solar panels will produce between about 100 W and 140 W at cloudless summer days. This should be enough for only the assistance at hills.

Dear GrayKard,

The most people have the same opinion about the “large” solar panels. But it is really sun-sailing, we need surface!
 
Make it a shade, with the support coming up from behind the seat post. That would be nice on hot sunny days. How heavy are those panels?
 
dogman said:
140 watts of what voltage? No way even 12v.
Click to expand...

Dogman, you're slipping into that voltage/current trap again. Watts are watts. It could be 12 volts at 11.67 amps, 28V at 5A, or 1V at 140A, etc. The voltage and current for a panel made with them will depend on the series/parallel wiring arrangement of the cells. To give you some perspective, the 6"x6" cells I have are considered 4 watt cells, about .5V & 8A in full sun, so 24 in series covering 6sqft would form a 96W panel with 12V 8A of output.

The real problem I see with the setup in the OP is if the plan is to generate useful electricity while riding, it needs to be at very low speed. Otherwise the increased wind resistance is likely to offset the power generated by the panels. That's why my suggestion to the gentleman wanting to do a solar bike for a 2000km ride was to arrange a 100-200W of panels into an aerodynamic form like a tailbox, and by means of mornings, long midday stop, and late afternoons, that several hundred watts of foldout panels are used to charge the battery pack. Of course, store bought panels won't work due to the weight, since solar panels aren't made for mobile use.

John
 
Yeah, there's a gap in my knowledge there for sure John. And depending on how he wires his panel, he could be getting 48 v out of em, or whatever.

But don't try to sell me that he's going far or fast with two small panels. He'll have some power for about an hour at noon, so he better plan on riding at noon, or rigging them to tilt, and riding due east or due west till the sun moves, and then he could ride north or south.

There is a reason there aren't solar bikes all over the place.
 
Well, I for one think this is a good project.

I wonder if some of the peeps criticising it are falling into the trap of thinking in terms of high speed and high power. Remember its a bicycle and you should compare it with a human powered bicycle, not one of the racing e-bikes we are talking about in other threads.

So figures like 80 W average and 250 W peak are useful. That's doubling what the ordinary utility cyclist will put in by human power and its enough to generate the E-bike grin.

Ok, its not going to do wheelies in the dark, but that's not what its setting out to do.

Nick
 
There are some reasonably light, fairly thin and slightly flexible solar panels around at a pretty good price. I bought four of these: http://www.sunflexsolarhk.com/product/sunflex-50w-flexible-solar-panel-50-watts-free-shipping-1 for my boat. I have them mounted on a canopy that's about 8ft long and a 3ft wide, fitted so there is a slight curve on the panels from side to side to both shed rain and look nicer. On a really good, cloudless day I can get around 150 to 180 watts from them around midday, using a maximum power point tracker (a Fatmax from here: http://solarmppt.com/product_info.php/cPath/23/products_id/33). Average power through the day is a fair bit lower, maybe 80 watts or so.

My guess is the panels on that bike will struggle to give more than maybe 40 to 50 watts at best, maybe less than that if there isn't an MPPT hooked up to it (the MPPT gives me around 10 - 15% more power from the panels into the battery pack).

Jeremy
 
Jeremy Harris said:
using a maximum power point tracker (a Fatmax from here: http://solarmppt.com/product_info.php/c ... ucts_id/33). Average power through the day is a fair bit lower, maybe 80 watts or so.
Click to expand...

Interesting MPPT - I have never seen one this light. The fact that it will drive a motor directly is interesting. Perhaps with a battery as backup power (diode included) when the MPPT drops out the battery could act as backup - rather it may not be too efficient to go the charge route unless stopped. I still like the dogman suggestion of a cart behind as this is an easy disconnect if the wind gets too unruly. The diffence with a bike vs a boat is that on a boat it is stable enough that you can even track the sun such as Wolfgang Schmidts system - but on a bike it is more important to track the wind and either use it or loose it quickly = quite a mechanical challenge.
 
dogman said:
...But don't try to sell me that he's going far or fast with two small panels...
Click to expand...

I never insinuated that. That doesn't mean that some form of solar bike isn't entirely possible. You live in the desert, so if you could get past the idea that it's impossible, you could easily build yourself a bike that would rarely, if ever, need to be plugged into the wall to charge the batteries. I don't have nearly the reliable sun that you have, and I have no doubt I can build a solar self charging ebike capable of harnessing the 500wh/day that I typically use. That's with good sun most days only until noon or 1pm. I won't get much solar power while riding, but that's for less than 30 minutes of the day. While parked is when you want to take full advantage of the sun. Once I have all my materials in hand I'll be putting my elbow grease where my mouth is.

Regarding a trailer for the panels...sure if you're going for the gusto in terms of panels, but for only 140W max output of panels it's not likely be worth the effort if that's the purpose of the trailer, because the extra rolling and wind resistance will eat up much of the power. A fold out tailbox appeals most to me, but my rides are short and fast, so improved aerodynamics plus a bit of solar power while riding plus lots of solar power while parked makes sense. For touring, then a recumbent trike with a solar paneled shade canopy makes sense, especially if you can angle it to the sun, though I'd still want extra panels to pull out and catch a couple of hours around noon.

Store-bought panels, unless you get something like what Jeremy linked, are probably best kept at home with some bulk storage capacity, so it can be your personal e-bike charging station, due to the weight and lack of aerodynamic shape of typical panels.

John
 
Ok, you're right. Nobody said fast. I just get peeved when I see blogs where people brag up their solar bike, and then show a panel that would take three days to charge my 36v 20 ah ping. Fine of couse, if you only need that much power per day. I just ride far, and think in terms of 1000 watthours a day usage.

Nothing wrong with charging a bike solar, I just object to the idea of trying to do it on the fly. Riding around getting 40-50 watts of power while suffering 80 watts of drag makes little sense to me. Mounted aero, that's a different story. But I just can't get my head around how to mount panels on the moving bike so they even run at half the watts they could if pointed into the sun. It could work on a long enough ride, on a straight enough road.
 
i think ur doing this the wrong way. Just my humble (newbie with still no ebike) opinion.

imagine it heavy, with big air displacement and dangerous aerodynamics, and ineficient with actual setup. U have to change something or else i think u will get hurt and or with a waste of money.

Maybe uf get hands on that promisse of that film solar cell, cheaper and lighter (also less eficient), and change pv panels placement.

I can only make other sugestions since i cant help u with ur actual idea...

Go green and buil a good "regular" ebike with a off-grid charge station. it will be cool also. Ur a enginer, put it to pay u back electric bill when not charging ebike, will help get some build money back, the green way!!

Or get a nice proudly made dutch velomobile (ur dutch right?), cover it with thin-pv cells or regular pv cells, stuff a 300w geared bafang in the drivetrain (shift gears!) , make a life/disability insurance and ride a bullet.

watch this vids of this all diferent velos

[youtube]BmmWUzsnbhk[/youtube]

[youtube]zlEi97dcQvk[/youtube]

[youtube]kwprOZbopWo[/youtube]

[youtube]nIFpMrQ3CgQ[/youtube]
 
Really, your best bet is to first concentrate on building a big enough solar system to charge your bike at home. Then if you get that accomplished, when you are not charging your bike you use that electricity to power something or charge other battery storage. After that, if your work location is (fixed) and (secure) you can have a charge station of appropriate size waiting for you there to recharge if necessary. Then after you have covered those most efficient ways of using solar, you can think about inefficiently charging your battery with solar traveling with you on your moving bike. Of course, if you are going to shade your bike from the sun, and initial money outlay is of less concern, shade your bike with a solar canopy. Having solar on board a boat is more viable and practical if you have the layout for it. It can help when there is no shore power available and you have extended stays afloat.
 
I would tend to agree the way to go is to use solar to keep a cheapo bank of flooded lead acid cells charged at home.

Have a little RC charger on the big dumb lead battery at home, and when you wish to charge the bike, plug in, hit charge, and you're set.

Get a 8-D sized flooded lead acid battery, and set it to float at ~80% SOC from the solar chargers.

IMHO, the pannels are best kept off the bike, as the energy from them transfers easily enough to the bike's battery from the energy capature/storage setup at home.

A big 8-D size flooded lead acid battery should last a number of years sitting at 80% SOC, and only getting dropped down to maybe 70% SOC after charging up the pack.
 
build a cheap bank of low esr lead-acid batts, wire it to arduino adc inputs and datalogg stuff, control charge and discharge etc.. ur mind is the limit..

optimal eficiency with a solar tracked pv array, (only one rotary axel design? cheaper to build) Several posts on web how to compare two adc inputs in arduino and using digital i/o and pwm to control salvaged printer stepper motor. The pv cells itself are the light sensors for optimal sun tracking.

Im not sure if a used tracking satelite dish gizmo would do the trick.

buy a cheap rc lipo/a123 charger, lipo batts or a123 depending on budget, a cicle analisty or battery monitor on hobbieking, stuff a hub motor and controler in the bike and u r a go.. with less a few hundred bucks/euros/pounds etc...

keep posting avandalen
 
Search and contact a professor in Ottawa , he has engineered flexible panels that fit each side of both wheels, learn the intent and limitations. This was commercial intent. Everybody else, listen up to Dogmans experience. Solar paint concepts may get worth while milliamps, the good prof knows this too (if comm. isn't viable maybe he'll share on ES). Hang some cardboard everywhere and repaint when its dirty, its that cheap. But good luck if you can afford panels.
 
Solar topic is worthwhile. See patent databases for the realities. Spend an hour learning how and see the benifit of science based verses google.com angles. Most everthing is expired, free to copy. Wheel skin concepts need rotating contacts, some costs. Solar paint works with simple one way circuit with small surface area like frame mounted, also paint the wall were you park your ebike. Paint concept is topping up, not a week long recharge. I suspect solar is better than regen by costs.
 
Florian Bailly has just completed a (partly) solar powered trip from France to Japan. The website's in French so I'm not sure how it turned out in detail, but he did do it. Here are the Google-translated facts and figures on the project:

To reach Japan, across 13,000 km in 100 steps, it requires a level of performance is quite remarkable.

The goal that I achieved is estimated between 130 and 160 km per day. 5:30 effort is a day to an average of more than 27/29 km / h.

With a basic bike, ATV + type trailers (all over 30 pounds) in 2006 I have held a daily average of about 100 km at an average speed close to settling the final 20km / h .

The contribution of energy supply must therefore allow me to significantly increase the efficiency of pedaling, so to increase the average speed.

Go fast, long while constantly renewing energy intake, this is the triple challenge of technology proposed by this project.

This technical challenge and I will raise it with support from the National Institute of Solar Energy (INES), which will help me conevoir this bike hybrid.

Oliver Wiss, researcher at the INES project and CTO, talks about the technical characteristics.

"The hybrid bike is built around a kit engine (Ludotechnologie) with a maximum power of about 350W and the associated engine controller.

Three batteries are used, one in use on the bike, one in charge in the trailer

The batteries will be lithium iron phosphate in 36V 10 Ah at an energy of 370 Wh per battery. Assuming a power consumption of about 4.6 Wh / km on average, three batteries used alternately expected to achieve the 160 km daily.


Recharging the batteries will be conducted using a specially designed photovoltaic module by INES to provide voltage and current compatible with batteries and use constraints. The photovoltaic module will be assembled on the basis of polycrystalline cells selected for optimum performance. An area of 0.9 square meters will provide a peak power of about 140W and earn daily energy of around 750 Wh with a correct forecast of the travel period considered. The module consists of two parts will be used entirely during periods of rest during the hottest hours of the day, which will also search for the optimal orientation, it will be used in reduced surface during taxi (fixed on the trailer ) in the morning and during the afternoon to optimize charging.

A charge controller and battery management system (BMS) will be specially considered by the INES for optimal use of solar power and charging lithium batteries correctly. "

------------------
I finally said, q'u in case of prolonged absence of sunlight, I should turn to conventional electrical outlets to recharge my batteries. And in case of simultaneous absence of sun and electrical outlets (in Mongolia and Siberia, for example), then I would satisfy me of my legs time to find a source of energy. With this in mind the overall weight of the bike should not be too important.
Click to expand...

This is not much use for commuting, but a good solution to this particular problem. The motor used was a through-the-gears type. You need to be pretty fit to pull a trailer for 5 hours a day at 12 mph (20 kph). At 30 kph, the rider is producing just under half the power required, which is why I said it was only partly solar-powered.. As a general rule of thumb, between 15 and 30 mph, increasing an ebike's average speed by 5 mph doubles the power requirement.
 
He is making a mistake by discharging the 36v 10Ah batts independently...

His internal resistance voltage sag could be cut by 1/3 on discharge, increasing energy usage efficiency, as well as the bump decreased by 1/3rd during charging if the packs were simply paralleled (which also reduces the need for 2 BMS units).

The charger should be put on the single combined battery pack and operated WHILE running rather than charging separately and swapping out, which pays an energy conversion loss cost in changing from electricity to chemical storage, and then from chemical storage back to electricity, when that power could be used directly in parallel to help supply the loads the battery is under to run the motor. (which would give better range/performance/use of available solar energy etc)
 
liveforphysics said:
He is making a mistake by discharging the 36v 10Ah batts independently...
Click to expand...

I wonder did anyone tell him that during his 100 days ride? :?

I suspect the most of the charging was done when the trailer was stationary. In the morning and evening the sun if low, and the panel horizontal, with a reduced area exposed. In the morning the rider would shadow the panel for much of the time. So, at a maximum, about 150 watt hours? Total saving in using it directly, less than 50 watt hours? Charging one battery at a time would mean that whenever he had to make an out-and-back detour from the route, he could leave the trailer set up for optimum charging and return to it later. But that's just speculation..
 
I wholeheartedly agree, Luke. That's exactly what I worked out when I was doing the energy calcs for my solar boat. The only time that the second battery scenario is of value is if you have more solar charge capacity at peak times than you can use (either for motive power or charging), when storing the excess makes sense (rather than letting it go to waste), although even then it'd be a better bet to just have a bigger single battery pack.

Jeremy
 
I speculate the french rider plugged in some. Nothing wrong with that. Carrying a small panel does help some, and areo matters less if the travel speed is slow carrying camping gear or something.
 
dodjob said:
Hi,
Even if the manufacturer claim 21% efficiency you won't get more than 17% in the best case (with Mppt and at lunch time in the summer).
I'm curious to know how much surface are you aiming ton mount on your bike? I have a 120W mono-crystalline panel (with "only" 16% efficiency) at home and it weights already something like 10Kg for about 1m².
it will deliver 120W max in the summer with full mppt control and manual orientation of the panel to get it 90° with the sun (at lunch time again ;) ).
100w on an ebike won't be sufficient to reach 25-30Km/h that's the good point :) you won't get problems with the police :).
grüß,
H.
Click to expand...
Yes I do not calculate on 21%.
The PV panel calculations are among other based on secure measurements (horizontal) in the sun. I use the best commercial Si solar cells available. The area is now 0.94m2.
See here for the PV panels
http://www.avdweb.nl/solar-bike/solar-panels.html
The solar panels should produce between about 120W and 150W at cloudless summer days. There are however many limitations of the solar bike, see here:
http://www.avdweb.nl/solar-bike/solar-bike-intro.html
 
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