Let your bike charge everwhere anytime: Solarpanels on EV´s.

[DasDouble]

Hi there,

in the last couple of months I was thinking about the princip of mounting solar panels on and into my future E-Bike, a Vector 4kW.
Now I have calculated everything a bit and want to share my results with you guys.

The sun is shining 1000W on 1m².
My solar panel will maybe have around 8% efficiency.
=> 80W per hour.
To calculate it a bit easyer let me say it has 10% efficiency.
=> 100W per hour.

My Vector Battery has 1,6kW/h.
=> For a full charge with perfect sun and best condition it would charge in 16 houres.
=> around two days and more.

With 1,6kW/h I can travel with a speed from 45 km/h all the time 164km.

Im from in school daily from 8am - 1pm. => 5 houres.

5 houres of charging my bike by solar panels of 1m² mounted on frame, and into front wheel I would get 0,5kW.
With 5kW I can travel with 45km/h around 29 kilometers. One way to school is 22 km.
=> Means just by charging it with my solar panels, without having to plug it into an energybox I could go home from school.


BUT WHY SHOULD YOU SPEND MUCH MONEY JUST FOR CHARGING YOUR BIKE THAT SLOW?

Here is my answer: Here in germany normaly you don´t have any problems to charge your bike. You have everywhere a power point. Charging is not the problem. The main thing I wan´t to solve is the problem of people who don´t like electric vehicles because they have to charge it every time and especially somewhere where a power point is and, or that long. With an efficient idea like mounting solar panels (which can be quite cheap if you build them by your own) on your bike, one of the reasons why people don´t like EV´s could be solved.

What do you guys think about it?


By the way: for calculating exact details I would need the size of 1 vectorframe. I have already got the size of a 27 bycicle front wheel: 0,369m².

 

[bobc]

Careful with solar panel rating.
Panels are rated on the basis of 1kW/m^2 energy flux input, square on, clean panels at 25C. You never get any one of these, never mind all of them at the same time.
If you search around you'll find maps of "equivalent sunshine hours". Where I live, in December the solar radiation AVERAGE is 0.9 equivalent sunshine hours per day. Bad days are a lot more like 0. BTW this winter has almost exclusively been made up of bad days.
So in an average December, lets say our 1m2 panel is 100W rated. If I have mppt (maximum power point tracking controller) AND I park it so it points most advantageously towards the light, and it's perfectly clean (& no unexpected shadows) I'd get an average of 100/24*0.9 = 3.75W. A 50V, 20Ah battery would take over 11 days to charge
I gotta say there are less depressing places to live than Manchester UK.....

 

[bobc]

PS - dasdouble - loads of "units" issues in your post, made it a bit hard to understand...
kW is kilowatts, a unit of power
kWh kilowatt-hours is a unit of energy, e.g. the "contents" of a 20Ah, 50V battery would be 1kWh
Ah Amp-hours is a unit of charge, normally used to describe a battery capacity
kW/h kilowatts per hour isn't a unit of anything really.... (rate of change of power????)

I appreciate English is probably not your first language & that I'm probably the last person who should be picky about this sort of thing, please don't be offended, I'm actually trying to be helpful

"With 1,6kW/h I can travel with a speed from 45 km/h all the time 164km" - I guess you mean 1.6kWh but 164kM at 45km/h doesn't sound feasible.

 

[dogman dan]

I live where solar energy potential is just about it's maximum, and yet the average year round is only 6 hours of insolation, for a panel mounted without tracking.

So the daily amount you'd get might be a lot less than you think, more like 4 hours on average than 8. more daylight of course in summer, and better angle to the sun generally.

Anyway, what I'm heading towards is this, your best bet to run entirely solar might be a compromise. You might run as much as a square meter on the vehicle, but then supplement your solar charging with a stationary panel at home, that is even bigger. My estimates have been that you'd need about an 150w panel at home to reliably refill 700 watt hours at my house daily. So you'd need something like double that, or more.

100 w panel on the vehicle should be pretty practical, then maybe 200w at home? Nothing at all wrong with the idea of having an extra 250-500wh a day on the vehicle, in the form of a solar panel, even if it doesn't work so great in mid winter.

If you have the cash for it, and can carry the panel easily, go for it. Most ordinary bicycles just can't carry a 100w panel very easily.

 

[Fastolfe]

This thread is particularly relevant to me, because I'm looking into installing solar panels on my velomobile for my trip to Finland this summer.

But I'm having second thoughts:

- 1000W/m2? Practically, not on your life. Especially in these latitudes, with the ubiquitous tree cover.

- I can install 2m2 of panels on top of my velo, but they'll be flexible/light (lesser efficiency - theoretical total 260Wp) and flat, when the sun shines obliquely there, even at noon. Plus, I fear that much surface on a light vehicle such as mine will be a constant danger on the road, what with the wind and trucks and all.

In short, I think you're way too optimistic...

 

[agniusm]

If you use Maxeon cells, you could get theoretical 448W power from 2m^2 of panel. You can check solar irradiation in different countries here: http://solarelectricityhandbook.com/solar-irradiance.html
I really like the idea of solar charging. I think such vehicle would be a blast in a town where distances are short.

 

[dogman dan]

Seems like a no brainer to put some panel on the vehicle, if it has a roof. Even if it's only good for 50w in your weather, it's still cool. Affordable, not really, but damn cool.

 

[johninclaflin]

I've started a project with my sons and youth in our community called the Solar Garage. I want to teach them about solar PV through experience. Our starting application was electric lighting the garage and recording a PV electricty production log. We started cheap with a 20w panel on a stationary mount and three lights and donated "scrap" batteries and $10 charger for $100. We are making incremental refinements such as a reflector, more and larger panels, home built solar tracking, and a maximum power point charge controller.We want to understand what matters and what is possible with solar where we live, without breaking the bank. We have several target applications beyond lighting. Charging my commuter ebike is one of those applications.

The early Ah charge numbers support Dogman Dan's point that we need at least a 150w panel to cover my summertime daily work commute. Even then we need a number of charge station batteries to hold several days of charge to make up for cloudy days. The best winter days recorded off the 20w panel gave 4.6 Ah at 12 volts of charge. That was with the refinement of a reflecting mirror mounted below the panel. This last week there was a lot of cloud cover, so a number of days had no charge. If I was reliant on the charge station to commute to work, I'd be fired. I run a 48v ebike system and last year 4 ah would get me to work and back. So I need 4x current production on a good day, and that is a measure of what is going into the charge station battery. No way I'll get all that back out. That said, a 150w fixed panel feels about right. Maybe in six months and some more money spent on refinements there will be real numbers to share.

Local utility power is $0.12 per kWh. A fun exercise was comparing the cost of our current solar station spread across 10 years of service life, to the current cost of the utility electricty. We are about 12x more expensive. We plan to repeat the exercise after every refinement to see how the comparison has changed.

I always get the question "why don't you mount PV on the bike?". My thought is leave the extra weight at home so I don't have to burn energy to carry it, and can't smash it up in a crash. But my travels are always "local", and my thoughts might change if I went further from home and needed a charge to get back.

 

[bobc]

My take on this is that for me, solar on the bike would work if the bike were only used occasionally, it could guarantee full batteries whenever you set off. A regularly well used bike would drain them faster than the number of cells you could fit on a bike would fill 'em. No reason not to use a stationary solar array for charging though, and a stationary array can be pointed reliably towards the sun....
Maybe things would be different if I lived in Tunisia...

 

[DasDouble]

- Maybe this flexible solar panel could be interesting for some of you guys:
[youtube]iVUhxDdV0ts[/youtube]

- Betaray, prototype:

I wish we could use this princip for our bikes. But carrying such a big waterball with me while riding isn´t the best thing I could do haha^^

[youtube]00C9KebsYVg[/youtube]

 

[dogman dan]

The weight is less of an issue now with the lighter semi flexible panels. But yeah, crash ( or just a mere tip over) damage needs to be considered.

I was really impressed with what's possible, when I saw the ride to the sun guys. But the bikes don't look good for commuting to me, with 3-4 meters of panel.

At one point, I was really convinced I wanted to build a solar panel carrying trailer for touring. Out here, really long distances between towns. And I liked the idea of ability to go where there are no plugs. So a solar boost to extend ranges to the 100-150 mile ballpark sounded great. However, the dream ended when I started touring, and sleeping on the hard ground. I'm just too old, wrecked back, wrecked rotator cuffs, I'm just plain done sleeping in a tent with a thin pad.

So now what I do is cheat. I car camp, with a bed I can sleep on in the car. The car can carry a small generator, so no problems to charge way up in the mountains. I can trail ride, charge, ride more, all day. Or I can take a road bike with big battery, and do a 30 miles out 30 miles back ride, then charge.

In town, It's also simple to carry enough for a 60 mile ride. So I'm not needing charging away from home. My bikes have changed, so now carrying up to 2000 wh of battery is no sweat. This bike for example, is pretty much all battery tray, with wheels stuck on the ends.