Around the world on a solar ebike

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E=IR   100 mW

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Re: Around the world on a solar ebike

Post by E=IR » Nov 05 2019 10:57pm

What do you consider the maximum width for solar panels on a trailer? Perhaps the same width as the handlebars?

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solarEbike   100 W

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Re: Around the world on a solar ebike

Post by solarEbike » Nov 06 2019 12:05am

E=IR wrote:
Nov 05 2019 10:57pm
What do you consider the maximum width for solar panels on a trailer? Perhaps the same width as the handlebars?
Assuming a solar panel made from 125 mm wide Sunpower cells, 6 cells wide seems to be the most common width among The Sun Trip participants although I've noticed one or two vehicles which used panels that were 7 cells wide. The Sun Trip Technical Regulations (PDF) impose a 99 cm (39") max width limit when the vehicle is moving. This allows additional slide-out/fold-out panels for stationary charging.

In my own test riding, I've found 6 cells wide to be a reasonable maximum width. This works out to be 80 cm (31.5") maximum trailer width when my panel is at a 0° tilt angle (horizontal) which is a little wider than my handlebars which are 76 cm (30") including left and right mirrors.

Since my trailer has a motorized tilt mechanism, I can easily tilt the panel at the touch of a switch to reduce my trailer's width when I need to fit trough a tight gap such as barriers at bike paths or passing cars stopped at traffic lights. It's wonderful to be able to do this on the fly but I certainly wouldn't consider it a requirement.

Also, consider the width of any doors you may want your trailer to fit through.
Fueled by burritos and solar power.™ SWB recumbent, Grin all-axle hub, Phaserunner, 6x LiGo battery, 248 watt sun-tracking solar trailer and 82 watt solar roof with 3 Genasun MPPT boost controllers (in progress), CA3 (solar FW), GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram

KarlJ   100 W

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Re: Around the world on a solar ebike

Post by KarlJ » Nov 10 2019 11:06pm

I worked for Boeing many years and I've drilled millions of holes in the stuff.
Just a quick one, carbon can be drilled more successfully with "dagger" drills and solid carbide at high speed will not suffer as much fibre breakout etc.
std operation for say a 3/16" hole would be a 1/8th dagger drill pilot hole and a 3 step solid carbide reamer to open up the hole, high speed is fine.
RE Carbon fibre dust - under the microscope carbon is not at all like asbestos and does not have a hook which asbestos does hence the human body deals with carbon fibre dust just fine.
RE electrical conductivity is very very low, the resin is nil and the dissimilar materials you mention is due to the hydroscopic nature of carbon and it does hold moisture, separation of aluminium and carbon in the aircraft industry is achieved with paint on the aluminium surfaces and polysulfide sealants which keep the moisture out of the joints which would otherwise gather moisture whilst the aircraft temperature changes rapidly during climb / descent. Terrestial much less of an issue and paint of surfaces in contact with each other should be sufficient.
My X wife occ hygenist (dust noise chemicals etc in industrial environments) did a project where rats were subjected to airborne cured carbon dusts and they only die when the amount becomes too much for their lungs to clear it. For humans thats a shit load of dust and you can work in a trimming booth for a day cut up hundreds of parts and have no ill effects other than black dust in your nose.

Hacksaw whilst it works, doesnt work for long and i suggest an angle grinder with cutoff wheel or better yet a diamond wheel that you would use for cutting ceramic tiles works a treat.

Happy cutting!

Awesome project - next level stuff - well done!

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solarEbike   100 W

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Re: Around the world on a solar ebike

Post by solarEbike » Nov 11 2019 2:46pm

KarlJ wrote:
Nov 10 2019 11:06pm
I worked for Boeing many years and I've drilled millions of holes in the stuff.
Hey Karl. Thanks so much for sharing your industry experience and knowledge about working with carbon fiber. I've cobbled together what I know mostly from working on a handful of fiberglass projects and doing an insane amount of internet research. The how-tos out there range from cringe-inducing YouTube videos of teenagers handling raw fiber and epoxy without gloves to academic papers and industry literature which can be difficult to adapt to a small workshop. Your practical advice is appreciated.
KarlJ wrote:
Nov 10 2019 11:06pm
RE Carbon fibre dust - under the microscope carbon is not at all like asbestos and does not have a hook which asbestos does hence the human body deals with carbon fibre dust just fine.
I think you're referring to when I wrote "Your body doesn't know what do with this stuff when it's embedded in your skin or your lungs." In hindsight, I'm not sure where I got that. I may have read that about carbon nanotubes and conflated it with some of the more alarmist precautions about working with carbon fiber in general. Definitely no nanotubes here. I assume you mean that wearing a good dust mask is a must but don't panic if you blow your nose later and see a few black particles.
KarlJ wrote:
Nov 10 2019 11:06pm
RE electrical conductivity is very very low, the resin is nil and the dissimilar materials you mention is due to the hydroscopic nature of carbon and it does hold moisture, separation of aluminium and carbon in the aircraft industry is achieved with paint on the aluminium surfaces and polysulfide sealants which keep the moisture out of the joints which would otherwise gather moisture whilst the aircraft temperature changes rapidly during climb / descent. Terrestial much less of an issue and paint of surfaces in contact with each other should be sufficient.
Good to know. A coat of paint is much simpler than always planning to have a layer of glass between fiber and aluminum. I assume my bike is going to be subjected to a lot of rain and occasional airborne salt when touring along coasts. The combination of water and salt tends to accelerate corrosion so I err on the side of caution when possible.

My concern about electrical conductivity is also based on a first hand account of a solar panel on a solar race car catching on fire. This was believed to have been caused by an electrical short through a carbon fiber body panel. I think the lesson is to remember that extra caution is required when routing wires through carbon body panels as opposed to fiberglass ones.
Fueled by burritos and solar power.™ SWB recumbent, Grin all-axle hub, Phaserunner, 6x LiGo battery, 248 watt sun-tracking solar trailer and 82 watt solar roof with 3 Genasun MPPT boost controllers (in progress), CA3 (solar FW), GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram

Cephalotus   10 kW

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Re: Around the world on a solar ebike

Post by Cephalotus » Nov 16 2019 2:33am

solarEbike wrote:
Sep 18 2019 4:10pm

Mostly, I’m breaking radio silence to share an interesting development that’s come to my attention recently. LightLeaf Solar is a new Canadian startup offering custom-made solar panels uniquely suited for use on an ebike: good weight/power ratio and integrated with a stiff structural panel so they’re self-supporting.
They do look nice. Thank you for the link.

Do you already have an indiction about the price they do ask per Wp and how much customization is available?
Last edited by Cephalotus on Nov 16 2019 2:54am, edited 1 time in total.

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solarEbike   100 W

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Re: Around the world on a solar ebike

Post by solarEbike » Nov 16 2019 2:53am

Cephalotus wrote:
Nov 16 2019 2:33am
Do you already have an indiction about the price they do ask per Wp and how much customization is available?
I do not have any specifics beyond what is on their web site and Instagram account. Based on the materials and the fact that these are being hand-assembled in small quantities in Canada, I would expect a price range of US$10-20 per watt. At least one page on their site seems to indicate they're willing to discuss any customization. Two other custom panel builders I've spoken with both had maximum panel sizes based on the dimensions of their laminating equipment but were willing to accommodate any custom shapes and designs within their fabrication abilities.
Fueled by burritos and solar power.™ SWB recumbent, Grin all-axle hub, Phaserunner, 6x LiGo battery, 248 watt sun-tracking solar trailer and 82 watt solar roof with 3 Genasun MPPT boost controllers (in progress), CA3 (solar FW), GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram

Cephalotus   10 kW

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Re: Around the world on a solar ebike

Post by Cephalotus » Nov 16 2019 3:16am

Do you happen to know about builders of custom made lightweight solar panels within the EU?

because of VAT, customs and transport and warranty reasons this is obviously the preferred choice for me living there.

I know about Solbian but afaik the do not make lightweight rigid panels. I'm still into that aluflex stuff that adds a bit more than 2kg per m².

My latest design idea is to us my six 50W panels at roughly 55cmx56cm (depends on how much I cut of from the sides) in a /\ configuration with 3 panels on each side, that can also change into a total / or \ or _ _ configuration. Prefered with motors, but Im not sure if I'm able to design a good auto tracking system, but maybe the benefit in that case would be rather small anyway.

At 30° angle the width would be smaller than 99cm and at a 60° angle the width of the array would be smaller than 60cm. This /\ setting could also be helpful when experiencing stronger side winds. For transport in trains etc. it would be nice if I could fold them down to the size of a single panel.
Obviously at least two MPP trackers are needed for each side. Reaction time when the sun is switching from left to right in a /\ setting is much quicker, because its pure electronic (MPP trackers finding the new MPP) vs mechanical, but the disadvantage is high weight. My solar panels plus aluflex do weight around 1,8kg for 50W or 11kg for 300W and this is without the tilting mechanism and the central main support pole.
The panels that you linked could probably be made at almost half that weight which would be a significant benefit.

Those 300W generator in a 30° angle at a /\ configuration throws only the shadow of a flat 165cm to 99cm solar panel (as long as the sun shines on both sides) and so will only produce as much energy as such a 165cm x 99cm panel vs the real panel size of 165cm x 112cm while riding (at sun trip rules with 99cm maximum width) from the direct radiation impact.
For the diffuse amount of radiation I don't know bit expect it to be closer to its real panel size.

Of course the power generation will be better at / , \ and _ _ configuration if the angle matches the direction of the sun, so this would be the preferred configuration during rest times.

Why I do want to to that?

1. Because I already do have those panels and otherwise it is not possible to stay below 1m width. I also want to keep the length of my solar generator below 2m.
2. Compared to a fixed flat setup at 165cm x 112cm the loss from direct radiation would be 99cm/112cm = ca. -12%. Because of the amount of diffuse radiation I guess the loss is lower than 10%.
When the sun is lower than 60° above the horizon from one side the shadow of that / \ array will be larger than the shadow of the flat _ _array, so the production will be better.
3. If the rider casts a shadow on the solar generator often the shadow will only hit one half of the generator, so only one half would be affected (the half that faces away from the sun anyway). This is only a benefit vs a solar generator with a single row of modules in series, not vs a 2x "3p" configuration.
I plan to use those three 50W moduls on each side in parallel connected by shottky diodes. I hope that the shadow by the rider will only affect one module. My modules are made from half cells so they have around 2,8A I MPP and around 17V U MPP, in parallel under ideal conditions that would be 18V (minus 0,2V for the diodes) and 8,4A which fits the Genasun Boost chargers.
It would be better to have one charger for each module, but sadly I can't shit money.
4. The generator can get smaller than 60cm in width when the panels are at 60° angle which should be helpful in some situations.
5. the / \ configuration could be less sensible to side winds than a / or \ configuration ???

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solarEbike   100 W

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Re: Around the world on a solar ebike

Post by solarEbike » Nov 16 2019 4:56pm

Cephalotus wrote:
Nov 16 2019 3:16am
Do you happen to know about builders of custom made lightweight solar panels within the EU?
I spoke with Gochermann in Germany in 2016. They do arrays for solar race cars, boats and the airplane that flew around the world. I was surprised that they were willing to work with me given the small project size but they had already done an order for at least one other ebike project. Be prepared for long lead times if your order is coming in around the same time as an upcoming solar car race.

I've been following Mito Solar on Instagram. They appear to be in the Netherlands.

For a budget option, take a look at LinkSolar. It's not ultralight encapsulation but they do custom work at around $3/watt. Sort of like a Chinese version of Solbian, maybe? Nick Henrys from New Zealand is building a bike for The Sun Trip 2020 using panels he got from them.
Cephalotus wrote:
Nov 16 2019 3:16am
My latest design idea is to us my six 50W panels at roughly 55cmx56cm (depends on how much I cut of from the sides) in a /\ configuration with 3 panels on each side, that can also change into a total / or \ or _ _ configuration.
It sounds like you're describing something like this configuration which I believe was used by a Sun Trip participant a few years ago? When I first saw it, I had a negative reaction to seeing so many solar cells oriented away from the sun. Assuming a 30° tilt from horizontal, I just ran some quick calculations on PVWatts comparing an East/West travel direction and North/South vs. flat mounting, all without tracking and the difference was only around 10% for year-round production which is consistent with your calculations. I certainly don't advocate for everyone using active tracking. As long as you can quickly and easily position your panels so that all the cells directly face the sun whenever you get off the bike, I think this could work.
TheSunTrip angled panels.jpg
TheSunTrip angled panels.jpg (115.02 KiB) Viewed 154 times
Fueled by burritos and solar power.™ SWB recumbent, Grin all-axle hub, Phaserunner, 6x LiGo battery, 248 watt sun-tracking solar trailer and 82 watt solar roof with 3 Genasun MPPT boost controllers (in progress), CA3 (solar FW), GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram

matmaxgeds   10 mW

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Re: Around the world on a solar ebike

Post by matmaxgeds » Nov 17 2019 6:01am

I also just saw this company who make solar canopies, maybe they have some economies of scale: http://motosola.com/

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