Prebuilt and OEM --- is it possible and recommendable to use a solar panel while riding?
Posted by catboy519@reddit | ebikes | View on Reddit | 44 comments
To me, electricity is not new to me but I dont know much about the BMS and software and controller things regardling the electricity.
My understanding is that
If bike controller demands more power than the solar can give: * The solar energy should reduce the amount of power drawn from the battery, therefore the battery drains slower (which is good, even for reducing the wear of the cycles!!)
AndIf bike controller demands less power than the solar can give: * Charger will power both the bike and the charging circuit of the battery (but how exactly does it distribute and what determines that)
But speaking of the BMS, controller, the complicated way an ebike works with 3 phase power and so on, would this idea possibly work? Are there any risks?
Lordly_Lobster@reddit
The amount of power you can get from a solar panel is 1360 Watts per square meter times the area of the panel times the efficiency. One square foot (probably about the most you would want to mount on a bike) is about 0.1 square meters and the efficiency is at most 20 percent. So you could get 1360.1.2 = 27 Watts. Assuming best case conditions of full sunlight and a properly angled panel. That's tiny compared to the power draw of an ebike. Not to mention the difficulty of engineering such a thing. You'd be better off buying a second battery.
Asleep-Specialist892@reddit
A small solar panel is not going to provide anywhere near enough power to ofset the additional weight of the needed equipment.
If you want to look into Solar, quick searches online show many sites with good information.
Solar Ebike Systems - Getting Advanced - Resources is just one of them.
catboy519@reddit (OP)
My plan is that the battery is still the primary power source. The solar panel is extra so even if its a little panel with 20 watts or less then its still a win then.
And I live in a flat country so the weight is hardly going to affect range. How much weight are we talking about?
chrispark70@reddit
I remember you. You're just a troll.
Agitated-Country-972@reddit
Nah, he's not a troll. He just likes "small hack, big payoff" while ignoring a lot of the systematic factors.
What he seems to do instead is fixate on clever-seeming edge-case ideas, reason about them in a narrow way, and then keep defending them long after the practical objections have already been answered.
That’s still a problem, because it makes discussions repetitive and frustrating, and it can look trollish from the outside. But I think the issue is more earnest overthinking, poor judgment, and resistance to updating than deliberate bait.
https://old.reddit.com/r/bicycling/comments/1i1e5ni/has_anyone_tried_using_umbrella_to_catch_tailwind/
chrispark70@reddit
I think the last post from him I saw was powering the world with margarine. Strange fellow.
Asleep-Specialist892@reddit
Look at the link I posted.
Look at the additional components you will need.
A small panel + the needed components is going to add weight, wind resistance and complexity, and new points of failure.
Its pointless.
Tomj_Oad@reddit
Are you sure the size solar panel you can carry will give enough power to run the controller?
If not it can't be worth it. I doubt it could be enough power to affect your mileage
catboy519@reddit (OP)
I think I should edit my post given that everyone seems to have this question. My primary powersource will be still be the battery. The solar panel is extra to get more range ontop of the battery.
Tomj_Oad@reddit
My question is will the panel produce enough to actually affect your range. I'd like to have an update.
If it works I have room on my baggage area for a foot square panel at least
catboy519@reddit (OP)
The udea is that the panel is extra so even 5 watts would theoretically help
Tomj_Oad@reddit
Let us know how that works out. Throw me a reply.
Agitated-Country-972@reddit
As someone with Kidney Failure and decreased exercise tolerance and endurance compared to a normal person, it'd be far better to get stronger legs and output the 5 Watts yourself than bother with a big clunky solar setup.
Pixelplanet5@reddit
step 1 is defining what is the largest solar panel you can have installed in a position where it actually works.
once you did that step you will immediately notice its not gonna work and the only way to get anything useful done with solar on a bike is to use a long and narrow single wheel bike trailer that has the solar panel as the top lid.
that way you can realistically fit a 100W panel on there and carry some stuff in the back.
catboy519@reddit (OP)
What I'm thinking of is: a small little solar panel (even if its 20 watts then I'm happy its better than nothing) probably just gonna place it simply horizontally over my rear rack or frame depending if the sun is in front of me or behind me.
The battery is the primary power source. The solar panel is just extra to get extra range.
Nova_Hunter@reddit
Bro a rear rack is not even big or can handle the weight of a legit panel. You're dreaming.
catboy519@reddit (OP)
So a single panel is more than 30kg? Racks are formally rated for 25kg but can handle more in real life.
And the panel can be bigger than the rack. It will simply stick out a little on both sidse and that is okay.
Nova_Hunter@reddit
So your rear rack is 65 inches long by 39 inches wide? That's 5'5" long and 3 1/4 wide. Your rack is that big? How about supporting it? You don't think these things through which makes me believe you are a troll.
Agitated-Country-972@reddit
catboy519@reddit (OP)
No one said I want such a huge panel. I was thinking more of about 1 by 1 meter or about 3 by 3 feet to 4
band-of-horses@reddit
The most practical way to solar power your bike is to use solar panels at home to recharge the battery.
catboy519@reddit (OP)
Thats what I'm already doing but thats not the point. The cost of electricity isn't the reason why I'm asking. I want to get extra range during rides and figured that a solar panel could help.
band-of-horses@reddit
Solar charge a spare battery at home and carry that along to swap in.
You're not going to get extra range from solar in any sort of reasonable or cost effective way. A bigger battery will be cheaper and easier. Unless you want to tow a frame with several full size solar panels it's just not going to happen.
At best you might get 20 watts or so per square foot of solar panel with a top tier panel, but that's only at the optimal angle which you cannot maintain while biking around and with no shading from your body or trees. In practice you will get more like 10 watts in full sun if you lay it flat, less if it's overcast. This might get you 2-3 extra miles of range if you're lucky.
To get anywhere useful you'll have to scale that 1 square foot up to 10-20 square feet which is not practical on a bike.
Youtube is full of people trying this if you want to see for yourself. They can be useful for recharging batteries, but it's impractical and of very limited benefit to try and extend range while riding without creating a custom trailer with large panels.
catboy519@reddit (OP)
I agree with you that panels give little power or need a very big surface area to give serious power.
But I don't agree with the idea that little power = near zero range improvement.
My ebike on eco mode can ride for 2 hours before the battery is empty so range becomes only a problem when I ride for longer than 2 hours.
Let's go with a 3 hours ride and a 30 watt panel. Thats 90 watt hours over the ride which means my range had increased by about 15% with just one little panel! And if I ride slower with less power by using the lower cutoff speeds, I can crank that 15% up even more.
band-of-horses@reddit
A panel rated for 30 watts will realistically put out 25 watts in the best of cases, and with occasional shading and non-optimal angles while riding on a bike, more realistically will put out 15-20 watts on a bright sunny day.
A lightweight, very efficient ebike like a Turbo Vado SL might be able to do about 8 watt-hours per mile in eco mode. So you might get somewhere around 2 miles extra range per hour, or 6 miles extra on a 3 hour ride.
If you feel like it's worth the hassle to be able to go 6 more miles, be my guest. IMO a range extender battery that can be solar charged would be a much more useful option but if you're determined to put a solar panel on your bike have at it.
Agitated-Country-972@reddit
Honestly I've gotten 10 Wh/mile on Turbo on my Vado SL before. Generally it ranges from 10-15 Wh/mile. Really depends on the wind though. But yeah considering I travel 15 miles in about one hour, 2 extra miles isn't really that significant.
thetonk@reddit
Tldr, no. Unless you plan on running a 12v 15A, maybe 20A motor. You would need to scale everything by a power of 3 maybe 4 to even trickle charge a half decent ebike. These pull a range from 36v to 52v. At the lowest, that's 3x.
When I go camping, I use my 280Ah 12v battery to charge my bike while that is charging on solar (400w, 2x renogy suitcase). I can charge my bike about 3 times before I get worried if it's not producing.
catboy519@reddit (OP)
I want to use my battery as the primary power source, simultaneously with the solar power as an extra. For the extra range.
The idea is, with some example numbers: if the controller asks for 100 watts and the solar panel gives 20 watts, then the battery only has to do 80 watts instead of 100, which increases my range by +25% alraedy. But even if the panel gives very little watts I'm still happy because its extra.
Problem I'm concerned about is not power and overheating... its how the BMS and Charger would respond to solar power in software terms. I think they expect the source of power to be 230V AC going through the charger then to the battery.
thetonk@reddit
BMS will act like the BMS on the solar setup. Just like you said but again, you have to convert it to whatever the battery/motor voltage is. Most small solar setups are 12v.
catboy519@reddit (OP)
My BMS has 3 pins and probably expects communication with the specific charger that comes with the bike. Thats my concern. * What would happen if I directly connected something to the + and - of my battery charge port while ignoring the third pin? * What would happen if I use my charger inbetween, but my charger receives less input power than the 230V AC it might expects?
Nova_Hunter@reddit
Yeah you're going to cause a thermal runaway, please steer clear of flammable places.
catboy519@reddit (OP)
Why do you think so? Solar panels give little power so theres no way they will overload the battery. It certainly wouldn't be the rate of charging or the voltage alone (cause even high voltage would just drop quickly if the solar panel cant handle the current the basttery is asking for)
But I believe that you may have a point
What would cause thermal runaway?
Nova_Hunter@reddit
Discharging it and charging it at the same time can probably cause damage leading to increased heat leading to dangerous things.
catboy519@reddit (OP)
Discharging it and charging it at the same time is not even possible, current cannot go both ways at the same time. Wrong?
I think either * the charger powers both battery and motor * or both the charger and battery together power the motor
Depending on the power that is needed
thetonk@reddit
Circular plug, 3 pons in a triangle like this?
catboy519@reddit (OP)
Yep thats almost exactly what it looks like.The numbers 1 2 3 are also positioned the same order!!!
thetonk@reddit
Are all your 3 connected inside the pack? I only have 2 of the 3 wired up and it's just + and -
catboy519@reddit (OP)
Opening the battery up voidsthe warranty so idk. But is there any other way to fiind that out without needing to open it?
thetonk@reddit
Not sure how yours is built but mine pulls out when I unscrew the 2 acrews. I didnt open the case.
chrispark70@reddit
This is a complete waste of time which will almost certainly reduce range and not increase it. It will be near impossible to attach a solar panel that will not induce extra wind and or rolling resistance.
Nova_Hunter@reddit
I love how ppl assume a solar panel is the answer to long distance riding and charging while u ride. It unfortunately doesn't work that way and it's all a pipe dream influencers give to guys like you.
Won't happen. Not while riding the bolts will be negligible and folding ones are much worse than a house panel which would be hilarious if you rode with one.
catboy519@reddit (OP)
If a panel provides 20 watt for a 5 hours long bike ride, thats 100 watthours extra range. If you do that with a 500 watthours battery, thats 20% extra range without the downsides of having to use a secondbattery(which would be calendar aging, weight, theft risk, and still not suitable for very long rides)
I know that a single little panel will provide little power but it would still be anice extra.
Ohm_Slaw_@reddit
The size of solar panel you could practically carry on a bicycle would provide a very small amount of power. Solar panels are large flat surfaces. You would have problems with wind resistance and stability.
There are have been some experimental solar powered ebikes. They have a custom-formed body that is one big panel. Take a look at those experiments to see what's involved.
catboy519@reddit (OP)
Yeh but even if the solar panel does 50 watt only... thats 150 watt-hours over a 3 hours ride, effectively making my battery +150 watt hours bigger.
For short rides, range should never be a problem. For medium rides, big battery is the way. But for truly long rides, I think a solar panel combined with a battery is the best way.
I still want my battery to be the primary power source of my ebike. The solar panel is just extra.
I know my bike can turn the motor while being charged (walk assist works while my ebiks is plugged at home) but my question is: is this possible with solar panels and do they need to be boosted or converted up to 230v such that I can plug my charger into the 230v? But would a charger even work if the power source lacks those amps? And if my bike is operating while plugged in, is it probably likely letting the charger do anything or blocking the charger? And is this safe? Are there any fire/damage/BMS lock dangers?
Thats essentially my question. Even if a panel is 20 watts only, I'm happy.