Around the world on a solar ebike

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wturber   100 kW

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Re: Let's talk Wh per kg

Post by wturber » Jul 18 2018 8:49pm

solarEbike wrote:
Jul 18 2018 6:15pm
wturber wrote:
Jul 18 2018 3:04pm
Looks like a good surface for some flexible amorphous solar cell ... Just thinkin' out loud ...
I hear you. And I tried to talk myself into it. I really did. Here's one concept I dreamed up and one I actually built a few years back.

curved-solar.jpg

Ultimately, I found that the thin-film stuff doesn't come close to top-end monocrystaline silicon on a Wh per kg basis, particularly when you consider that you need twice the surface area and twice the structural support hardware.
Oh - I was already quite sure that amorphous solar cells - especially when curved - wouldn't come close to a monocrystaline flat array that gets aimed even halfway decently. My musing was simply that given you already have the structure built is it worth slapping some of them on? Could they help defray the weight penalty of the fairing structure itself? Perhaps neither makes sense in the end on their own. But together?
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
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solarEbike   10 W

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Re: Let's talk Wh per kg

Post by solarEbike » Jul 18 2018 11:01pm

wturber wrote:
Jul 18 2018 8:49pm
Oh - I was already quite sure that amorphous solar cells - especially when curved - wouldn't come close to a monocrystaline flat array that gets aimed even halfway decently. My musing was simply that given you already have the structure built is it worth slapping some of them on? Could they help defray the weight penalty of the fairing structure itself? Perhaps neither makes sense in the end on their own. But together?
Ok, I'll play along. Let's run the numbers.

This 47W PowerFilm peel-n-stick product on eBay is advertised as 38" x 48" so about the same size as my fairing design. I would have to modify the design to fit the panel but I think it could be done. The seller claims it weighs 5 lbs but the seller also claims the 37W and 55W version they're selling are also both 5 lbs so we know that's BS. This PowerFilm PDF lists a similar looking 30W product as weighing 1.76 lbs so let's say 47/30*1.76 = 2.76 lbs plus 0.41 lbs for the additional MPPT controller this will require and we're at 3.17 lbs (1.44 kg). That would triple the weight of my fairing!

47W PowerFIlm on eBay.jpg

Given the extreme curvature of the fairing, I would expect it to produce half the rated output (even less when my head is shading it) but let's be generous and pretend I spend all of my charging hours stopped by the side of the road with the fairing laid out flat on the ground.

In comparison, to add 47W to my trailer would require just 13 additional SunPower Gen III Bin Le1 cells at 3.62W/cell. With the honeycomb support panel I'm using and ultralight encapsulation at 800 g/m^2, 13 additional cells would only add 0.95 lbs (0.43 kg). No additional charge controller would be needed because the existing controllers can handle the extra cells.

Sorry. Even when the support structure is "free" because it's already there, thin film is still too heavy. And at $8.78/watt with shipping (or $17/watt if you're going to mount it in a way that gets you half the output) it's more expensive than the race-grade panels used by most of the teams in the (currently ongoing!) American Solar Challenge.

There are applications for thin film solar panels but a solar ebike is not one of them.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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wturber   100 kW

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Re: Around the world on a solar ebike

Post by wturber » Jul 19 2018 11:32am

That makes sense. it seems like the amorphous cell suffers a doubly whammy in low efficiency to start with and an even lower efficiency once mounted on a curved surface.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
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Re: Around the world on a solar ebike

Post by Delik » Jul 30 2018 5:26pm

I like the simplicity of the design enabled by a single wheel and furthermore by not including cargo capacity in the trailer. The frame looks like it has some modular components. What did you fabricate it out of?
solarEbike wrote:
Jun 20 2018 6:17pm
Cephalotus wrote:
Jun 19 2018 4:14am
Did you build the trailer yourself or is it based around a commercial product?
Does it offer suspension? (difficult to see)
The trailer is my own design. Using BOB trailer hardware to attach to the bike otherwise scratch built. There's a lightweight elastomer suspension using a Cane Creek Thudbuster with about 1" (25 mm) of travel. I'll increase the travel a little for the next build.
elastomer-suspension-detail.jpg


The last part finally arrived today for my new and improved motorized panel tilt mechanism: an adjustable clutch to protect the drive assembly from overload in case of fall, crash, limit switch failure, etc. No idea if this will work but the idea is that it fits entirely inside the main boom tube (1.5" / 38 mm ID). Claimed torque of the motor/gearbox is 30 KG-cm (2.9 N-m) which is easily 2-3 times what's needed to move the panel thanks to the torsion spring to take the weight of the panel off the gearbox at 75° tilt. Add a shaft-mounted potentiometer, some photosensors, sprinkle some Arduino on it and you have automatic single-axis tracking inside a water and dust resistant housing. 1.55 lbs (703 g) for the parts shown here.

panel-tilt-drive-assembly.jpg

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solarEbike   10 W

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Re: Around the world on a solar ebike

Post by solarEbike » Jul 30 2018 6:32pm

Delik wrote:
Jul 30 2018 5:26pm
I like the simplicity of the design enabled by a single wheel and furthermore by not including cargo capacity in the trailer. The frame looks like it has some modular components.
I tried a 2-wheeled Burley Flatbed cargo trailer before this (project history here) but I didn't like how it limited my top speed, hit many more potholes (due to the 3 tracks) and limited the range of tilt of the solar panel. The one wheeled solution is more challenging to attach to the bike but allows much more panel tilt and banks into turns with the bike. The realization that I didn't need the trailer to carry any cargo was a big "A ha!" moment and allowed me to save further weight by not having to over-build the trailer to handle 50-100 lbs (25-50 kgs) of trailer plus cargo bouncing around on rough roads for thousands of miles.
Delik wrote:
Jul 30 2018 5:26pm
What did you fabricate it out of?
If you're asking about the trailer shown in the photographs, this is what I've been thinking of as my "penultimate prototype." The main boom tube is 2" ABS DWV drain pipe available from my local home improvement big box concern. It's cheap and readily available but turned out to be too flexible so I reinforced it with an outer wrap of carbon fiber (unidirectional fabric layer followed by biaxial sleeve outer layer). That made a huge difference. The red panel is 1" (2.5 cm) XPS rigid house insulation foam covered with 5.5 oz/yd^2 (185 g/m^2) fiberglass cloth/epoxy skin with extra layers on the edges and corners.

If you're asking about the CAD sketch, that's what I hope will be the "final build" I take on the road for the long haul. I'm starting from scratch taking all the lessons from previous builds and aiming for much lower weight and nearly twice the solar power. The main boom will be entirely made of carbon fiber with 3 telescoping segments which nest inside each other (Rock West Composites, not cheap). The flat panel support surface will be Nomex (aramid fiber) honeycomb with carbon fiber/Kevlar skins.

I'll post photos of the new build once I'm further along.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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A deep dive into bypass diodes

Post by solarEbike » Aug 10 2018 6:32pm

Are you considering a solar trailer for your ebike? Do not underestimate the impact of even small amounts of shading on your solar array, especially if you're using SunPower cells.

As a 10 year veteran of the residential solar industry with extensive experience modeling PV energy production on shade-challenged rooftops, I thought I was pretty knowledgeable about the impact of partial shading on solar modules. However, I’ve recently learned something about SunPower cells which surprised me.

Try to guess what the power drop will be due to the following shading situation. About 25% of the cells are shaded so you might imagine that it would be around 25%, right?

riding position wth self-shading issue.jpg

Actually, it's closer to 90%.

Huh? ... but why? These are two 94W panels made by Solbian with genuine SunPower cells. At over US $7/watt, they are definitely a premium product and not your garden variety $2/watt Chinese semi-flex panels made with SunPower's assembly line reject cells. I've bought enough of the latter to appreciate the difference.

And yes, these modules have bypass diodes installed. If you’re unfamiliar with bypass diodes as used in photovoltaic panels, I recommend you read this first. I won't cover the basics here.

If you had asked me to guess what the drop would be in the image above, I probably would have guessed "a little over 50%". My reasoning would have been that since at least 1-2 cells are shaded in 3 out of 6 substrings then 3 out of 6 of the bypass diodes should be activated so that the current is shunted around them and that since each active bypass diode dissipates several watts of energy, that adds up to a little over 50% of the total. If this was a traditional mono or poly silicon module made with non-SunPower cells, I might have been right but as I've recently learned SunPower cells are different.

Here's the unshaded array with all 60 cells connected in series to one Genasun MPPT boost controller. 148 watts from a nominal 188 watt array is typical given the slightly less than optimal tilt angle and cell temperature around 50-60°C. The green lines indicate which cells are part of the same substring group, each with its own a bypass diode.
148W_no_shade.jpg

Now look what happens when I shade just three cells (2 on one substring and 1 on another). The power drops from 148W to 19W.
19W_3_cells_shaded.jpg

And here's what happens with 20 cells shaded. Surely the bypass diodes should activate at this point and we should be getting full power from 4 out of 6 substrings, no? For some reason, the bypass diodes are not activated and the shaded cells are opposing the current flow.
5W_20_cells_shaded.jpg

Now look what happens when I completely block the same 20 cells. A "hard shadow" if you will. (Please disregard the paper "cells" on my shading implement. I wasn't planning to publish these results.)
88W_20_cells_shaded.jpg

Interesting. We're now getting 88W which is consistent with 2 bypass diodes activating (148W total - 2/6*148 for the bypassed cells - a few watts for the heat dissipated by the 2 active diodes).

And finally, here's the same situation but this time using 2 MPPT controllers. We're only getting 70W instead of 88W with the hard shadow so it looks like the bypass diodes are not activated here and the power from the shaded panel is close to zero while the unshaded panel remains unaffected because it is now connected to a separate MPPT charge controller.
70W_20_cells_shaded_2_controllers.jpg

For the two of you who are still reading after all of that, here's the payoff which got me to post this. I direct your attention to this SunPower white paper. From pages 20-24 we learn:
a typical conventional cell has a breakdown voltage of approximately -15V to -20V, whereas the SunPower cell’s breakdown voltage is only about -5.5V for its second generation Maxeon cells and -2.5V for its third generation Maxeon cells.
and
SunPower does include diodes in its J-boxes, but the diodes do not turn on when only one cell is shaded. The voltage drop
across a single reverse-biased cell is not sufficient to drive significant current through the diode. SunPower includes diodes only to increase the production of the system in the case that several cells in the same substring go into reverse bias. In this case, the diodes limit the total amount of power that can be dissipated by reverse-biased cells.
Except when they fail to activate due to the lower breakdown voltage and the power loss is significantly greater than the contribution of the shaded cells.

My final solar trailer build will consist of 4 PV modules with 4x6 cells each. The two modules closest to the bike will each have their own MPPT tracker and the two furthest from the bike will be connected in series to a third MPPT tracker. I'm also planning to use "smart bypass diode" devices (SM74611 made by TI) which have a forward voltage of only 26mV (take that, Schottky diodes!) and power dissipation of around 300mW which will help with the tiny junction boxes I'm integrating into my panels. I'm not sure they'll fare better than the results above but I think they're worth a shot.

And yes, I know, a solar array mounted over my head would virtually eliminate this problem but I'm still pretty sold on this trailer idea.

PS: Apologies to all the electrical engineers out there for any terms I may have butchered above. I dropped out of engineering school and majored with a BA in French.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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wturber   100 kW

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Re: Around the world on a solar ebike

Post by wturber » Aug 10 2018 8:18pm

I'd consider adding a bit more distance between the solar trailer and bike as well.

You could also look into acquiring an invisibility cloak so that you would cast a shadow on the cells and you could build the bike out of transparent aluminum. Just a few thots. :^)
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
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1JohnFoster   1 kW

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Re: A deep dive into bypass diodes

Post by 1JohnFoster » Aug 19 2018 4:33pm

solarEbike wrote:
Aug 10 2018 6:32pm
~I’ve recently learned something about SunPower cells which surprised me.
Wow, frustrating to learn at such a late date!

Is it possible to re-wire so all the strings run perpendicular to your direction of travel to minimize those affected by your shadow? (Sorry, not sure I understood your green lines.)

Too bad there aren't PV controllers that could switch cells dynamically in a matrix. The voltage drop would be negligible with small relays ... though you wouldn't want relays for a trip around the world.

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solarEbike   10 W

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 20 2018 12:37pm

wturber wrote:
Aug 10 2018 8:18pm
I'd consider adding a bit more distance between the solar trailer and bike as well.
Definitely. I had always intended to leave more space but the prototype trailer shown above is my first successful one-wheel trailer design. Previous versions failed because the main trailer boom tube flexed too much: it's basically a driveshaft whose purpose is it prevent the transmission of torque. I shortened it just to get a working model so I could validate the one-wheeled trailer concept and field-test the tracking. For the final build, I will be using much lighter ad stiffer carbon fiber tubing to eliminate lateral and torsional flex and I'll move it a little further back. I'll still get the same shadow but it will be later/earlier in the day.
1JohnFoster wrote:
Aug 19 2018 4:33pm
Is it possible to re-wire so all the strings run perpendicular to your direction of travel to minimize those affected by your shadow? (Sorry, not sure I understood your green lines.)
The cells are wired in series, parallel to the direction of travel. The green lines indicate which groups of 10 cells are on the same bypass diode. Maybe it would have been clearer if I had drawn boxes around each group? Theoretically, two or more shaded cells in any group of 10 should activate the bypass diode and cause it to short-circuit those 10, allowing current to flow around the shaded cells thereby limiting the power loss to just those 10 cells. In reality, only a hard shadow caused by an object laying directly on top of the cells triggers this behavior. Normal shadows don't trigger the bypass diode and the power loss is much greater than just the 10 cells.

I've had custom PV modules made for me so I could have had them wired any way I wanted. I kept the same parallel-to-the-direction-of-travel cell wiring based on optimal wire routing and junction box placement. Had I considered the shading mitigation issue, I'm not sure if wiring the cells perpendicular to the direction of travel would have helped much since the bypass diodes aren't activating when cells are shaded under typical real-world conditions. My solution is to move the trailer a little further back and put the most shaded PV module on its own MPPT tracker.

The diagram below shows typical bypass diode wiring. This is not my PV module.

Bypass diode wiring.jpg
Bypass diode wiring.jpg (91.53 KiB) Viewed 462 times
1JohnFoster wrote:
Aug 19 2018 4:33pm
Too bad there aren't PV controllers that could switch cells dynamically in a matrix. The voltage drop would be negligible with small relays ... though you wouldn't want relays for a trip around the world.
Interesting idea, but how would each relay know when to activate? Assuming we want this to function automatically, the only signal I can think of to use would be voltage across the cells connected to the same relay, looking for negative voltage instead of positive to detect that the cells are in reverse bias due to shading. This is how traditional bypass diodes work. I suppose that it might be possible to design a circuit where the bypass occurs at a different voltage threshold. Hmmm, definitely outside my comfort zone.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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My new custom solar modules have arrived!

Post by solarEbike » Aug 20 2018 1:05pm

My custom-made PV modules arrived last week. Here's a quick peek at what they look like. The red/black panel is the honeycomb/carbon fiber/kevlar support panel on which I will be mounting them. There are four modules with 4x6 cells each for a total of 96 SunPower Gen III bin Le1 cells at 3.62 watts each. Assuming around 5% encapsulation losses (3-5% reflection plus some transmission losses), the total PV array rated output at STC should be around 330 watts. Realistically, 250-300 watts under real-world conditions in full sun. That's still 75% more than my current trailer. Under ideal solar conditions on flat, paved roads with no headwind, I should be able to maintain a speed of 20 mph (32 kph) on a fully loaded touring ebike with pedaling and still have a net input of energy into the battery pack. I can't wait to get this show on the road.
Attachments
SunCat Solar module front.jpg.jpg
SunCat Solar module backside.jpg
SunCat Solar module encapsulation thickness.jpg
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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Re: Around the world on a solar ebike

Post by LockH » Aug 20 2018 3:06pm

Hehe... Sorry... coming late to this thread. Watt we know so far "Search found 0 matches: velo"... as in "velomobile"?... My human body suffers from "too hot" and "too cold". Were I, would ride encased in a shell/body wrapped in thin film solar cells...sorta like:
Image

... in a heated or cooled cabin. :)

As soon as yer hitting 20+ MPH yer hitting wind resistance... noticeably...

Carry on Sir. :)
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Re: My new custom solar modules have arrived!

Post by wturber » Aug 20 2018 3:16pm

solarEbike wrote:
Aug 20 2018 1:05pm
Assuming around 5% encapsulation losses (3-5% reflection plus some transmission losses), the total PV array rated output at STC should be around 330 watts.
So I'm assuming there is no practical/economical anti-reflection coating for the encapsulation compound?
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 20 2018 3:54pm

LockH wrote:
Aug 20 2018 3:06pm
"velomobile"?...
Looking at the speed and distance covered by people touring in velomobiles, I couldn't help but notice that they were similar to what I was doing with an ebike except they didn't have a motor or batteries that needed constant charging. I even flew to Holland to test ride a Mango velomobile in 2016. Ultimately, the logistics of transporting a velomobile across oceans ended that idea. I would still like to have one some day. Witness the grin induced by the first test ride:

velomobile.jpg
Last edited by solarEbike on Aug 20 2018 4:24pm, edited 1 time in total.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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Re: Around the world on a solar ebike

Post by multifrag » Aug 20 2018 4:00pm

solarEbike wrote:
Aug 20 2018 3:54pm
LockH wrote:
Aug 20 2018 3:06pm
"velomobile"?...
Looking at the speed and distance covered by people touring in velomobiles, I couldn't help but notice that they were similar to what I was doing with an ebike except they didn't have a motor or batteries that needed constant charging. I even flew to Holland to test ride a Mango velomobile in 2015. Ultimately, the logistics of transporting a velomobile across oceans ended that idea. I would still like to have one some day. Witness the grin induced by the first test ride:


velomobile.jpg
What about a recumbent? It has a similar position and aerodynamic advantage over normal road bike position. You can pack it into a normal bicycle box. The only problem is stop and start is more difficult, but you can get used to it. Some recumbent even come with a tear shaped back end compartment

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Re: My new custom solar modules have arrived!

Post by solarEbike » Aug 20 2018 4:11pm

wturber wrote:
Aug 20 2018 3:16pm
solarEbike wrote:
Aug 20 2018 1:05pm
Assuming around 5% encapsulation losses (3-5% reflection plus some transmission losses), the total PV array rated output at STC should be around 330 watts.
So I'm assuming there is no practical/economical anti-reflection coating for the encapsulation compound?
Short answer: no, not really.

The encapsulation consists of two sheets of fluoropolymer film with some kind of flexible adhesive goo in between. Most of the solar race car teams have their solar modules encapsulated by one of two small companies that specialize in this niche. I've spoken with both of them and they've both told me the same thing: the highest performing anti-reflective treatments are currently good enough to reduce encapsulation losses to nearly zero. One experimental option even promises to slightly improve performance over bare cells! But they're all very fragile and not at all suitable for a round the world trip. They're barely able to withstand the wear and tear of a single race. The surface is prone to soiling and is very difficult to clean without damaging it. This only makes sense when your budget is in the hundreds of thousands of dollars and you build a new car for each race, and an extra 1 or 2% can make the difference between first and second place in a race where the design limit is the square surface area of your PV cells.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 20 2018 4:20pm

multifrag wrote:
Aug 20 2018 4:00pm
What about a recumbent? It has a similar position and aerodynamic advantage over normal road bike position. You can pack it into a normal bicycle box. The only problem is stop and start is more difficult, but you can get used to it. Some recumbent even come with a tear shaped back end compartment
That was my conclusion as well. Here's the design I'm working on. The bike has a hinge in the middle so it folds in half. The motor eliminates any difficulties in starting from a stop, even on the steepest hills with a fully loaded bike.

tailbox and trailer side.jpg
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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LockH   100 GW

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Re: Around the world on a solar ebike

Post by LockH » Aug 20 2018 4:24pm

Hehe... "Ultimately, the logistics of transporting a velomobile across oceans"... The last time I flew with an electric bike, it folded down and was in a sports equipment shoulder bag and went no charge, as my "luggage". Speaking of airships... EVer wonder how small a zeppelin would shrink in it wasn't full of hydrogen? :mrgreen: Point is only... the "canvas-covered collapsible velo" covered in thin film solar watt fits in a bag for "transporting across oceans". (That is, until yah get those inflatable sponsons...) :lol:
ES changed my life (for the waaaaay better).

Eff. June, 2014 Phoenix Ebike Promotions

(Current ride? High speed lawn chair.)
viewtopic.php?f=3&t=57408

Phoenix Ebike Promotions conversion kit (work in progress. More drink holders, etc etc)
viewtopic.php?f=15&t=60564

Joined yer local chapter of EA yet?
(Ebikers Anonymous - Where we're all miserable failures, but the parties are hilarious...)

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Re: Around the world on a solar ebike

Post by multifrag » Aug 20 2018 4:28pm

solarEbike wrote:
Aug 20 2018 4:20pm
multifrag wrote:
Aug 20 2018 4:00pm
What about a recumbent? It has a similar position and aerodynamic advantage over normal road bike position. You can pack it into a normal bicycle box. The only problem is stop and start is more difficult, but you can get used to it. Some recumbent even come with a tear shaped back end compartment
That was my conclusion as well. Here's the design I'm working on. The bike has a hinge in the middle so it folds in half. The motor eliminates any difficulties in starting from a stop, even on the steepest hills with a fully loaded bike.


tailbox and trailer side.jpg
That's a lovely design! Have you considered making a custom small windshield for your feet to lower the turbulence? Did you consider situation where your panel might get damaged as during this suntrip I've noticed at least 3 bikes had some problem with rigidity or even bent solar panels.

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solarEbike   10 W

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 20 2018 5:29pm

multifrag wrote:
Aug 20 2018 4:28pm
That's a lovely design! Have you considered making a custom small windshield for your feet to lower the turbulence?
Thank you. It's been a long process with a lot of iteration (more on that here). I commuted to work for a few months with this front fairing. It was lovely for keeping my feet warm and dry during the rainy winter months here but I didn't notice any improvement in aerodynamics. From what I've read on HPV racing forums and blogs, the conventional wisdom about partially faired bikes seems to be that a tail fairing is much more effective than a front fairing.

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multifrag wrote:
Aug 20 2018 4:28pm
Did you consider situation where your panel might get damaged as during this suntrip I've noticed at least 3 bikes had some problem with rigidity or even bent solar panels.
I've given that a good deal of thought and I've been paying attention to the Sun Trip crash damage. Some of those panels look to me like they weren't adequately supported but I don't believe it's practical to try to build an "indestructible" solar panel for an ebike. I've taken a number of steps to mitigate the risks:
  • My carbon fiber/honeycomb core support panel is built significantly stronger (and heavier) than it needs to be to hold the encapsulated solar cells
  • I used a hybrid Kevlar/carbon fiber fabric to hold the panel together in case of major impact
  • The solar module will be bonded to the support panel with silicone adhesive along the entire surface area
  • The motorized tilt mechanism has a mechanical clutch which allows it to slip if it hits an obstruction or is forced to tilt in a crash
  • My 96 solar cells are divided equally among 4 separate modules with 3 separate charge controllers so even if one fails completely, the others can keep working
  • My solar panel bypass diodes will located in sealed junction boxes I can open if needed for troubleshooting and replacing a failed diode or fixing wiring issue
  • My 4 solar panels are connected with hinges that allow the array to be folded with the vulnerable top surface on the inside. This should help with occasional hazards like sandstorms/hail as well as transporting the bike by bus/truck in an emergency or ferry/plane when needed
Also, SunPower cells have a metalized back side which theoretically allows cracked cells to continue to operate as the cell fragments remain connected in parallel through the metalized back side (white paper here). I've been told by one of the solar race car teams that they estimate losses at roughly 10 watts per cracked cell. I'm guessing the reduced current carrying ability of the damaged cells limits all the other cells in the same series string?

And finally, since I've built my trailer from scratch, I should be able to make repairs on the road if needed. For minor problems, I'll carry a small repair kit including epoxy and repair fabric. I don't expect to finish the trip with no damage at all but hopefully I'll only lose a little bit of capacity due to mishaps along the way. :D
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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solarEbike   10 W

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 20 2018 5:51pm

LockH wrote:
Aug 20 2018 4:24pm
Speaking of airships... EVer wonder how small a zeppelin would shrink in it wasn't full of hydrogen? :mrgreen: Point is only... the "canvas-covered collapsible velo" covered in thin film solar watt fits in a bag for "transporting across oceans". (That is, until yah get those inflatable sponsons...) :lol:
I'm not at all tempted by the idea of attempting a solo ocean crossing by any means but I seriously looked into the idea of doing all my ocean crossings by sailboat. There are plenty of opportunities to volunteer as crew on a ocean going sailboats but the popular routes and seasons don't align well with long-distance overland routes that made sense to me. I'm still hoping to do it at least once, possibly from Cape Town to South America but more realistically from Australia to Bali.

But if I'm going to be honest, this whole contraption is really just a substitute for what I actually want. George Lucas promised me a future full of hoverbikes. The future is here but when was the last time you saw a hoverbike?
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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LockH   100 GW

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Re: Around the world on a solar ebike

Post by LockH » Aug 20 2018 6:09pm

^^ Hehe... Have traveled many thousands of miles... using sails for "free" solar energy. It was boats that got me into electric traction using betteries in the first place. So. Now yer trip "Around the world" on a solar eboat? :lol:
ES changed my life (for the waaaaay better).

Eff. June, 2014 Phoenix Ebike Promotions

(Current ride? High speed lawn chair.)
viewtopic.php?f=3&t=57408

Phoenix Ebike Promotions conversion kit (work in progress. More drink holders, etc etc)
viewtopic.php?f=15&t=60564

Joined yer local chapter of EA yet?
(Ebikers Anonymous - Where we're all miserable failures, but the parties are hilarious...)

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grindz145   100 MW

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Re: A deep dive into bypass diodes

Post by grindz145 » Aug 21 2018 7:30am

solarEbike wrote:
Aug 10 2018 6:32pm

5W_20_cells_shaded.jpg
Just found this thread, and I am very much looking forward to following your journey for the next few years!

One technical question: How did you generate the video above, with the human/solar/ etc input measurements?

Thanks!
-Troy

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wturber   100 kW

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Re: A deep dive into bypass diodes

Post by wturber » Aug 21 2018 9:54am

grindz145 wrote:
Aug 21 2018 7:30am
solarEbike wrote:
Aug 10 2018 6:32pm

5W_20_cells_shaded.jpg
Just found this thread, and I am very much looking forward to following your journey for the next few years!

One technical question: How did you generate the video above, with the human/solar/ etc input measurements?

Thanks!
-Troy
I don't know what he used, but you can do overlays like that using Dashware and just about any logged data source.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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fechter   100 GW

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Re: Around the world on a solar ebike

Post by fechter » Aug 21 2018 1:25pm

solarEbike wrote:
Aug 20 2018 5:51pm
But if I'm going to be honest, this whole contraption is really just a substitute for what I actually want. George Lucas promised me a future full of hoverbikes. The future is here but when was the last time you saw a hoverbike?
They're actually out there now, but the range isn't so good:
https://www.youtube.com/watch?v=soxxPyaAT1k

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"One test is worth a thousand opinions"

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solarEbike   10 W

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Re: Around the world on a solar ebike

Post by solarEbike » Aug 21 2018 2:53pm

grindz145 wrote:
Aug 21 2018 7:30am
Just found this thread, and I am very much looking forward to following your journey for the next few years!
Hey Troy! Just seeing your 2014 trip thread for the first time. Great stuff. Just lost an entire morning and I'm only half way through. I hope I leave behind an equally compelling tale of tears and triump.
wturber wrote:
Aug 21 2018 9:54am
grindz145 wrote:
Aug 21 2018 7:30am

One technical question: How did you generate the video above, with the human/solar/ etc input measurements?
I don't know what he used, but you can do overlays like that using Dashware and just about any logged data source.
Yup. Dashware to convert log data into video overlay. Frankly, it was a lot of work to configure it for the first video since it doesn't recognize CA log files but the upside is that it's infinitely customizable in terms of data types and display options. I was able to save the first one as a template and doing future videos should be much simpler. The 1080p video files are huge and it takes forever to process the video overlay so I won't be doing a lot of them but maybe I'll try to record an epic day here and there. More details about all the tools I used can be found in this post: viewtopic.php?f=6&t=94721&start=25#p1391380
fechter wrote:
Aug 21 2018 1:25pm
solarEbike wrote:
Aug 20 2018 5:51pm
... The future is here but when was the last time you saw a hoverbike?
They're actually out there now, but the range isn't so good:
https://www.youtube.com/watch?v=soxxPyaAT1k
Love Colin Furze. I guess my complaint is that I expected them to be ubiquitous by now. :wink:
William Gibson wrote:The future is already here – it's just not evenly distributed.
SWB recumbent, Grin all-axle hub (5T in 20" wheel), Phaserunner, 6x LiGo battery, 330 watt sun-tracking solar trailer with 3 Genasun MPPT boost controllers (in progress), CA3 (SolarAnalyst firmware), GPS Analogger, Rohloff IGH. Solar ebike build, Website, Instagram, YouTube

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