Around the world on a solar ebike
- solarEbike 100 W
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Around the world on a solar ebike
Um… hello. I’m imagining this post will become the introduction for what will eventually become a mega-thread over the next several years so I feel some pressure to make it a good one.
I’ve been tinkering with adding solar charging to an ebike for a little over 10 years. The goal has always been to add enough solar power to the bike to offset the additional weight of the motor, batteries and solar panel while extending the range compared to a fully loaded touring bike without electric assist.
This is easy moderately difficult to do if you cherry pick your riding days and only count cloudless summer days. But on a long distance bike tour you don’t have the luxury of being a fair weather rider so this equation needs to include foggy, cloudy and rainy days as well. In other words, my average day on a long distance tour needs to be better than riding a bike without all that extra weight and clutter. An ebike with a dead battery is no fun. I think I’m close to accomplishing that goal.
Here’s the penultimate prototype:
And here’s what’s on the drawing board:
What about the “around the world” part? Right. Almost forgot. I’m building this crazy contraption so I can take the ultimate victory lap when it’s ready: head west and keep going until I return to my starting point and/or meet myself. Whichever comes first.
I’ve posted a brief history in pictures of this project on my blog. There are a few photos up on Instagram and a couple of short videos on YouTube. I expect to have more content for a non-technical audience once I’m posting from the road. In the meantime, I figure this is the best place to discuss all the nitty gritty technical details.
Cheers,
Mark
PS: There’s an in-depth video coming soon to the Grin YouTube channel so subscribe now to get a notification when it comes out.
UPDATE: The video is now available here: https://www.youtube.com/watch?v=7RGBBNctWNA
UPDATE 2: If you're here because you're thinking about adding solar to your own ebike, start by reading How to convert your ebike to a solar ebike. It's my synopsis of lessons learned (as of August 2020) with hardware recommendations and solar panel sizing tips.
I’ve been tinkering with adding solar charging to an ebike for a little over 10 years. The goal has always been to add enough solar power to the bike to offset the additional weight of the motor, batteries and solar panel while extending the range compared to a fully loaded touring bike without electric assist.
This is easy moderately difficult to do if you cherry pick your riding days and only count cloudless summer days. But on a long distance bike tour you don’t have the luxury of being a fair weather rider so this equation needs to include foggy, cloudy and rainy days as well. In other words, my average day on a long distance tour needs to be better than riding a bike without all that extra weight and clutter. An ebike with a dead battery is no fun. I think I’m close to accomplishing that goal.
Here’s the penultimate prototype:
And here’s what’s on the drawing board:
What about the “around the world” part? Right. Almost forgot. I’m building this crazy contraption so I can take the ultimate victory lap when it’s ready: head west and keep going until I return to my starting point and/or meet myself. Whichever comes first.
I’ve posted a brief history in pictures of this project on my blog. There are a few photos up on Instagram and a couple of short videos on YouTube. I expect to have more content for a non-technical audience once I’m posting from the road. In the meantime, I figure this is the best place to discuss all the nitty gritty technical details.
Cheers,
Mark
PS: There’s an in-depth video coming soon to the Grin YouTube channel so subscribe now to get a notification when it comes out.
UPDATE: The video is now available here: https://www.youtube.com/watch?v=7RGBBNctWNA
UPDATE 2: If you're here because you're thinking about adding solar to your own ebike, start by reading How to convert your ebike to a solar ebike. It's my synopsis of lessons learned (as of August 2020) with hardware recommendations and solar panel sizing tips.
Last edited by solarEbike on Aug 06 2020 12:15pm, edited 2 times in total.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
- solarEbike 100 W
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Re: Around the world on a solar ebike
A few build photos to get the ball rolling.
Custom fabricated battery box with room for wiring, spares and tools. Magnetic latches, waterproof charging port and integrated heatsink for Phaserunner.
Wiring channels cut into foam for PV output, LED lights and photosensors for automated tilt mechanism.
Testing the lights.
Foam sealed with fiberglass and epoxy. Aluminum inserts embedded with extra layers of fabric for attachment points.
Back side of PV modules before attaching to foam support panel. Using extra-thin double-sided foam tape suitable for low surface energy plastics to ensure lasting bond with solar backsheet material. Note junction boxes on back side of panel. On the next build I will bond the entire surface with GE Sillicone II rather than using double sided tape.
Fabricating bracket for Grin motor torque arm.
And here's the finished bracket. The bracket is threaded and there's a nut on the back so I can adjust the clamping force on the carbon fiber suspension fork independently from the clamping force to the torque arm. Should make it easier to change tires and fix flats. If you're certain I'm going to die a horrible death because I'm using a front hub motor with a carbon fiber suspension fork, check back on this thread in a couple of years. I've got 1100 miles (1770 km) on it so far and it's holding up just fine with regen braking.
Back of the panel showing tilt mechanism via 12V linear actuator, elastomer suspension, and almost no visible wiring.
Riding position showing self-shading on solar panel when riding toward the sun early and late in the day. This is definitely a design trade-off. I didn't do a solar roof because it would make the bike top-heavy and more susceptible to cross-winds. The next build will have the solar trailer a little further back.
And finally, a profile view to better show the bike geometry. The next build will use a similar bike but both wheels will be 20" and the bike will have a folding hinge in the middle for easier transport.
Custom fabricated battery box with room for wiring, spares and tools. Magnetic latches, waterproof charging port and integrated heatsink for Phaserunner.
Wiring channels cut into foam for PV output, LED lights and photosensors for automated tilt mechanism.
Testing the lights.
Foam sealed with fiberglass and epoxy. Aluminum inserts embedded with extra layers of fabric for attachment points.
Back side of PV modules before attaching to foam support panel. Using extra-thin double-sided foam tape suitable for low surface energy plastics to ensure lasting bond with solar backsheet material. Note junction boxes on back side of panel. On the next build I will bond the entire surface with GE Sillicone II rather than using double sided tape.
Fabricating bracket for Grin motor torque arm.
And here's the finished bracket. The bracket is threaded and there's a nut on the back so I can adjust the clamping force on the carbon fiber suspension fork independently from the clamping force to the torque arm. Should make it easier to change tires and fix flats. If you're certain I'm going to die a horrible death because I'm using a front hub motor with a carbon fiber suspension fork, check back on this thread in a couple of years. I've got 1100 miles (1770 km) on it so far and it's holding up just fine with regen braking.
Back of the panel showing tilt mechanism via 12V linear actuator, elastomer suspension, and almost no visible wiring.
Riding position showing self-shading on solar panel when riding toward the sun early and late in the day. This is definitely a design trade-off. I didn't do a solar roof because it would make the bike top-heavy and more susceptible to cross-winds. The next build will have the solar trailer a little further back.
And finally, a profile view to better show the bike geometry. The next build will use a similar bike but both wheels will be 20" and the bike will have a folding hinge in the middle for easier transport.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
Re: Around the world on a solar ebike
That's an awesome project on so many levels...
- John and Cecil 10 kW
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Re: Around the world on a solar ebike
I can understand boating or flying around the world, but how would you ride a bike around the world? It is not even possible to walk around the world except with oxygen supply equipment and heavy boots to keep you on the ocean floor. 
It is very cool though!

It is very cool though!
- solarEbike 100 W
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Re: Around the world on a solar ebike
I assumed the inflatable pontoons were implied.John and Cecil wrote: ↑Jun 13 2018 3:20pmI can understand boating or flying around the world, but how would you ride a bike around the world?
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[Rats. I told myself I wouldn't feed the trolls. Must. Try. Harder.]
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
- John and Cecil 10 kW
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Re: Around the world on a solar ebike
Dude, if you could build inflatable pontoons on that and actually go around the world I think you might end up with a movie offer 
Seriously though I was not messing with you, I truthfully do not understand how it could be considered riding around the world if you cannot possibly make it all the way. You would obviously need to fly or take a ship to cross the oceans, and those routes coule be different. Do you have to stop at every island and ride across it, or do you pass over some land masses. If the plane took the correct route you might only need to cross the usa and fly the rest of the way over water. It would seem more accurate to be considered crossing several continents, or even all of them.
I think it would be a great accomplishment though, and we will be rooting for you!

Seriously though I was not messing with you, I truthfully do not understand how it could be considered riding around the world if you cannot possibly make it all the way. You would obviously need to fly or take a ship to cross the oceans, and those routes coule be different. Do you have to stop at every island and ride across it, or do you pass over some land masses. If the plane took the correct route you might only need to cross the usa and fly the rest of the way over water. It would seem more accurate to be considered crossing several continents, or even all of them.
I think it would be a great accomplishment though, and we will be rooting for you!
Re: Around the world on a solar ebike
I think "riding around the world" is akin to "walking around the city." It does not imply that the person will cover every inch of the periphery of the city - but that he will cover a lot of ground.John and Cecil wrote: ↑Jun 13 2018 4:49pmSeriously though I was not messing with you, I truthfully do not understand how it could be considered riding around the world if you cannot possibly make it all the way.
My girlfriend and I once rode across Europe, but we took a train through the mountains in the Ardennes. Still a lot of fun, and got to see the world from very close up.
--bill von
- John and Cecil 10 kW
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Re: Around the world on a solar ebike
Yes, I have been looking it up and there are people who have walked around the world and they were not in fact Jesus
It makes a big difference which way you go I guess.
The bike with the solar panel trailer is awesome! I wouldn't mind a small cargo trailer with a solar panel top, and maybe a small sunscreen for Cecil made with a small solar panel. I was also considering those roll up solar panels so you can charge your battery while spending the day at the beach. I wish they were not quite so heavy and they were more efficient though.
Still very cool!

The bike with the solar panel trailer is awesome! I wouldn't mind a small cargo trailer with a solar panel top, and maybe a small sunscreen for Cecil made with a small solar panel. I was also considering those roll up solar panels so you can charge your battery while spending the day at the beach. I wish they were not quite so heavy and they were more efficient though.
Still very cool!
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Re: Around the world on a solar ebike
Go for it!John and Cecil wrote: ↑Jun 13 2018 10:23pmI wouldn't mind a small cargo trailer with a solar panel top, and maybe a small sunscreen for Cecil made with a small solar panel.
I would add a coroplast panel to keep the PV panel from flexing too much and just attach it with zip ties. If you're in the US, $216 plus tax and shipping for trailer, solar panel and boost charge controller. I don't vouch for any of these personally but that should be a good starting point.
EDITS: Fixed link rot.
Last edited by solarEbike on Oct 11 2019 1:09pm, edited 2 times in total.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
- John and Cecil 10 kW
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- Joined: Mar 14 2018 7:26pm
Re: Around the world on a solar ebike
I see they have decent semi flexible panels now. I just saw a 200w one that is 57" x 31". Perhaps it can be used as a curved roof over an open trailer like a conestoga wagon when riding and when parked the sides can extend up and flatten it out to take in more sun. The wind must be brutal on those panels though. When riding a motorcycle in windy conditions you can really feel the force by merely pointing your knee to the windward side. I often use my knee as a sail to help tack into the wind when getting blown sideways on the freeway.
Maybe the curved flexible panels would work ok for a trike too. The wind should pass through it like wind going through a tunnel. It would be nice to be able to generate enough power so the bike/trike can travel on sunny days with no need to charge the battery, or possibly even carry a battery (direct power).
*Ah, I found something similar online that someone made already:
Maybe the curved flexible panels would work ok for a trike too. The wind should pass through it like wind going through a tunnel. It would be nice to be able to generate enough power so the bike/trike can travel on sunny days with no need to charge the battery, or possibly even carry a battery (direct power).
*Ah, I found something similar online that someone made already:
- solarEbike 100 W
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Re: Around the world on a solar ebike
When I was 11 years old, my parents gave me a copy of the Guinness Book of World Records. It was a cheaply printed mass-market paperback and I kept thumbing through that volume until it fell apart. The world’s oldest human, the jump rope endurance record, the man who ate an entire bicycle. The more preposterous, the better. The stories of human endurance stayed with me the longest. I was approaching puberty and my body was about to experience all kinds of magical changes. Maybe I would grow the longest human tongue?
More recently, I read Christopher McDougall’s Born to Run and experienced that same sense of wonder about what the human body can accomplish when pushed to the limits of endurance. Our evolutionary heritage as a species has left us poorly equipped for sitting in front of screens all day long. But running down antelopes on the Savannah? Our bodies are uniquely suited to the task. Most of us have just forgotten.
Until a few days ago, I believed the origin of this project was a fully loaded 2000 mile (3200 km) bicycle tour of Italy I completed in 2006 but now I’m thinking this all started with that book.
When I started planning the route for this adventure it only made sense that I would consult the oracle of St. James Gate, Dublin. They define around the world cycling for record purposes like this:
What do you all think?
EDIT: Updated map June 2019. Live map here.
More recently, I read Christopher McDougall’s Born to Run and experienced that same sense of wonder about what the human body can accomplish when pushed to the limits of endurance. Our evolutionary heritage as a species has left us poorly equipped for sitting in front of screens all day long. But running down antelopes on the Savannah? Our bodies are uniquely suited to the task. Most of us have just forgotten.
Until a few days ago, I believed the origin of this project was a fully loaded 2000 mile (3200 km) bicycle tour of Italy I completed in 2006 but now I’m thinking this all started with that book.
When I started planning the route for this adventure it only made sense that I would consult the oracle of St. James Gate, Dublin. They define around the world cycling for record purposes like this:
And that the routeThe journey should be continuous and in one direction (East to West or West to East), that the minimum distance ridden should be 18,000 miles (29,000 km), and that the total distance travelled by the bicycle and rider should exceed an Equator's length, i.e. 24,900 miles (40,100 km)
But this is my trip and I'm making my own rules. For one thing, I think you should actually travel the length of the equator by bicycle to offset the fact that you’re crossing the oceans by other means. My proposed route consists of:must be ridden through two approximate antipodal points.
- 60,000 miles (100,000 km) total distance including water crossings
- 40,000 miles (65,000 km) over land
- 6.5 continents (Antarctica is a definite maybe)
- One pair of antipodes
What do you all think?
EDIT: Updated map June 2019. Live map here.
Last edited by solarEbike on Jun 02 2019 2:42pm, edited 2 times in total.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
Re: Around the world on a solar ebike
That does look pretty epic. I have trouble just going 50 miles.
Question: how much does the solar panel weigh?
Question: how much does the solar panel weigh?
"One test is worth a thousand opinions"
Re: Around the world on a solar ebike
Excellent project fechter, know your pain and motivations.
Would be very interested in your charge controller of choice/why, and would recommend anyone looking into doing a similar project to also consider a bifacial module, can generate electricity from both sides.
My experience with a 75 lb trailer plus PV panels written previously here on Endless Sphere and at this blog: http://renewableenergyspace.blogspot.co ... solar.html energyi
Would be very interested in your charge controller of choice/why, and would recommend anyone looking into doing a similar project to also consider a bifacial module, can generate electricity from both sides.
My experience with a 75 lb trailer plus PV panels written previously here on Endless Sphere and at this blog: http://renewableenergyspace.blogspot.co ... solar.html energyi
HS3540 20" on Terratrike Tour Recumbent, LifePO4 48V 20 amp (was 12S2P Lipo), Greentime controller w/regen. Denver Area.
Re: Around the world on a solar ebike
Me too. It was a thick (2" or so) book and it was printed on flimsy paper; it got pretty tattered after a while, but it was great for car trips.solarEbike wrote: ↑Jun 15 2018 2:31pmWhen I was 11 years old, my parents gave me a copy of the Guinness Book of World Records. It was a cheaply printed mass-market paperback and I kept thumbing through that volume until it fell apart. The world’s oldest human, the jump rope endurance record, the man who ate an entire bicycle. The more preposterous, the better. The stories of human endurance stayed with me the longest.
I just got a hardcover version (with pictures) for my kids, 4 and 6. And I'm even in one of the pictures.
--bill von
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Re: Around the world on a solar ebike
The whole trailer is 30 lbs (14 kg), the tilting red support panel without the PV modules is 7 lbs (3 kg) and the PV modules are 2.9 lbs (1.3 kg) each. I'm now building what will hopefully become the version I take on the road and it should come in at a lower weight and have 350 watts of solar on it. Weight reduction using lots of carbon fiber and custom fabricated PV modules with ultralight encapsulation.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
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Re: Around the world on a solar ebike
Genasun GVB-8 boost controller. Designed by former MIT solar race car team members. MPPT updates 15 times per second for use on a moving vehicle. Proven track record with past and current The Sun Trip participants.
Do your bifacial modules have separate outputs for the front and back facing cells? I've encountered them several times as an option for solar carports during my residential/commercial solar career but never found a project where they were the most cost effective solution.
I seriously considered adding two additional rows of cells mounted on long hinges so they face down while riding and swing out 180° to charge when stopped. You can see the back of my panel is designed to accommodate this. But then I ran the numbers and it just didn't pencil out for me. I would mostly need the extra panels on days when I'm trying to do 100-200 miles (150-300 km) but then I consider that I won't have time for long stops on those days so the cells that don't face the sun while riding (and their support structures) negatively impact my Wh per kg number. Albedo irradiance is only a tiny fraction of direct irradiance.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
Re: Around the world on a solar ebike
Bifacial cells are cells with transparent backing so that they generate from both sides. One output; it just can receive light from both sides.solarEbike wrote: ↑Jun 15 2018 4:17pmDo your bifacial modules have separate outputs for the front and back facing cells?
--bill von
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Re: Around the world on a solar ebike
Ah. That explains why the bifacial module data sheets I've seen all have just one pair of outputs. I incorrectly assumed they were made with two cells back to back. Well, I'll consider anything that can get me more Wh per kg than my current setup.
BTW, I love the solar camper trailer concept. There's a guy with a camper in this year's The Sun Trip. I'm betting he's the envy of the group when it's time to set up and strike camp every day.
I tried to design a pop-up tent concept that used my trailer as a support structure but just couldn't get it lighter than my 2.7 lb (1.2 kg) 1.5 person backpacking tent.
I also have a design constraint that my entire rig has to be able to fly with me on a commercial flight. That eliminated some other range-extending possibilities like this velomobile I test-rode in Holland two years ago.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
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Re: Around the world on a solar ebike
Outstanding project!solarEbike wrote: ↑Jun 15 2018 2:31pmWhen I was 11 years old, my parents gave me a copy of the Guinness Book of World Records. It was a cheaply printed mass-market paperback and I kept thumbing through that volume until it fell apart. The world’s oldest human, the jump rope endurance record, the man who ate an entire bicycle. The more preposterous, the better. The stories of human endurance stayed with me the longest. I was approaching puberty and my body was about to experience all kinds of magical changes. Maybe I would grow the longest human tongue?
More recently, I read Christopher McDougall’s Born to Run and experienced that same sense of wonder about what the human body can accomplish when pushed to the limits of endurance. Our evolutionary heritage as a species has left us poorly equipped for sitting in front of screens all day long. But running down antelopes on the Savannah? Our bodies are uniquely suited to the task. Most of us have just forgotten.
Until a few days ago, I believed the origin of this project was a fully loaded 2000 mile (3200 km) bicycle tour of Italy I completed in 2006 but now I’m thinking this all started with that book.
When I started planning the route for this adventure it only made sense that I would consult the oracle of St. James Gate, Dublin. They define around the world cycling for record purposes like this:
And that the routeThe journey should be continuous and in one direction (East to West or West to East), that the minimum distance ridden should be 18,000 miles (29,000 km), and that the total distance travelled by the bicycle and rider should exceed an Equator's length, i.e. 24,900 miles (40,100 km)But this is my trip and I'm making my own rules. For one thing, I think you should actually travel the length of the equator by bicycle to offset the fact that you’re crossing the oceans by other means. My proposed route consists of:must be ridden through two approximate antipodal points.I didn’t grow the world’s longest tongue. And while I did grow up to be freakishly tall, it’s nothing for the record books. The thought of having to register with Guinness in advance and having to keep daily records and having to collect signatures along the way seems like a giant hassle. But now that I’m reminiscing about that old record book maybe the 11 year in me would like to be in the book.
- 60,000 miles (100,000 km) total distance including water crossings
- 40,000 miles (65,000 km) over land
- 6.5 continents (Antarctica is a definite maybe)
- One pair of antipodes
What do you all think?
proposed route as of June 2018.jpg
I wish you succes!
As a long time bicycle rider, the only hardship that always bothered me is the the traffic whizzing by.
In all developed countries there is no way to avoid high speed traffic, there are no roads (in my experience) where one can enjoy the peace of pedalling along and imerse oneself into the surroundings without man made interference and eventually risks and discomfort or even danger.
None the less you are a brave man and i will keep my fingers crossed for your biking enedeavour or for your tongue to grow as much as you like.
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Re: Around the world on a solar ebike
Wow that map is EPIC!
I was a little proud of myself for doing only 15 miles the other day... LOL!

- solarEbike 100 W
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Re: Around the world on a solar ebike
I hear you. Sharing the road with cars takes some getting used to. I've been ebike commuting 20 miles a day for most of the last 10 years Rain or shine. Half of that has been along side of traffic. It helps if you make good decision like riding assertively and defensively as the situation dictates. It helps if you assume cars don't see you. I use two mirrors on my bike, wear high visibility clothing, run very bright lights day and night, never ride with headphones, etc. but none of these will do me any good against the teenager behind the wheel looking at their phone instead of the road. But what's the alternative? Staying home? Joining the traffic jam, stuck in a metal box on wheels? No thank you.andrebandre wrote: ↑Jun 15 2018 9:08pmAs a long time bicycle rider, the only hardship that always bothered me is the the traffic whizzing by.
I may not be able to lick my eyebrows but I did eventually learned to speak in four different tongues, which is likely to be more useful on this adventure.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
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Re: Around the world on a solar ebike
Have you tested your panel in hot sun? It all looks great though I'd want to use the panel for shade like my motor customer who took his solar ebike all the way around Australia. I ask about the panel testing, because with the foam I'd worry about heat buildup, which is a big concern with factory built panels here in the tropics where the sun is stronger. The heat reduces panel efficiency and reliability. Since cells are designed to absorb as much sun as possible and what doesn't get converted to electricity becomes heat, I'd worry whether the foam and resins can handle the temps.
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Re: Around the world on a solar ebike
Good point. Heat is a legitimate concern. I've done about 500 miles (800 km) of road testing with this red foam panel, including a couple of days with 100°F (38°C) ambient air temperature so assuming solar cell temps are 25°C above ambient, that's hot enough to slow-cook an egg. Under those conditions, large blisters appeared between the fiberglass/epoxy skin and the extruded polystyrene (XPS) rigid construction insulation foam. Not enough to compromise the integrity of the panel, but it probably wouldn't survive three years of bouncing around the world. I suspect the culprit was outgassing from the foam at elevated temperatures. It turns out that this is a known issue among surfers who use certain types of XPS foam cores.John in CR wrote: ↑Jun 16 2018 7:59amHave you tested your panel in hot sun? It all looks great though I'd want to use the panel for shade like my motor customer who took his solar ebike all the way around Australia. I ask about the panel testing, because with the foam I'd worry about heat buildup, which is a big concern with factory built panels here in the tropics where the sun is stronger. The heat reduces panel efficiency and reliability. Since cells are designed to absorb as much sun as possible and what doesn't get converted to electricity becomes heat, I'd worry whether the foam and resins can handle the temps.
I've talked to the guy who builds ultralight PV module assemblies for most of the North American solar race car teams and he told me to expect up to 75°C (167°F) cell temperatures based on race conditions in Texas. I believe the fluoropolymer top and bottom sheets and the encapsulant will be able to handle that but I'm switching out the foam core for Nomex honeycomb and using an epoxy with a higher glass transition temperature (Tg). First test build video:
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram
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Re: Around the world on a solar ebike
This is what I plan to use to stabilize my "semiflexible" solar modules.
It's called Metawell Aluflex, it's made of aluminum and weights around 2,2kg/m²:
https://www.metawell.com/wp-content/upl ... hl_h47.pdf (sorry, datasheet is in German)
It's bendable in one direction, but quite rigid in the other if you glue the flat surface to the module. In that case the area to dissipate heat on the rear is extended. I plan to do some thermal tests in the upcoming weeks...
I also use solar modules with ETFE front side instead of the cheaper PE versions. ETFE will last much longer under hot conditions ans also does not reflect as much light as PE, which imho is a real security concern when using low mounted panels in traffic.
It's called Metawell Aluflex, it's made of aluminum and weights around 2,2kg/m²:
https://www.metawell.com/wp-content/upl ... hl_h47.pdf (sorry, datasheet is in German)
It's bendable in one direction, but quite rigid in the other if you glue the flat surface to the module. In that case the area to dissipate heat on the rear is extended. I plan to do some thermal tests in the upcoming weeks...
I also use solar modules with ETFE front side instead of the cheaper PE versions. ETFE will last much longer under hot conditions ans also does not reflect as much light as PE, which imho is a real security concern when using low mounted panels in traffic.
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Re: Around the world on a solar ebike
Nice. Haven't seen that one before. My Nomex (aramid) honeycomb core panel in the video above came in at 1.2 kg/m² with 5.5 oz/yd² (186 g/m²) cloth on both sides and my second test was 1.0 kg/m² with a lighter cloth on one side. Given the Sunpower Gen III cell temperature coefficient of power is -0.29%/ºC, I would need to see a significant cell temperature drop to offset the extra weight. It's all about the Wh per kg for me.Cephalotus wrote: ↑Jun 16 2018 11:40amIt's called Metawell Aluflex, it's made of aluminum and weights around 2,2kg/m²
2015 The Sun Trip winner Bernard Cauquil is using aluminum honeycomb for his current panel.
Absolutely. Fluropolymer topsheet is the way to go. My current and future panels have this as well.Cephalotus wrote: ↑Jun 16 2018 11:40amI also use solar modules with ETFE front side instead of the cheaper PE versions. ETFE will last much longer under hot conditions ans also does not reflect as much light as PE, which imho is a real security concern when using low mounted panels in traffic.
Current setup: SWB recumbent, Grin All Axle hub w/ Statorade, 2x Phaserunner, 6x LiGo+ battery, 238 watt sun-tracking solar trailer and 76 watt solar roof with 3 Genasun MPPT boost controllers, CA3 w/ solar FW & GPS Analogger, Rohloff hub. Solar ebike build, Website, Instagram