You have one or two motors, one or two batteries depending on what you’re trying to do, and then operator power if it’s pedal assisted or not if it’s full throttle.
Ebikes seem pretty straightforward, but when you throw solar power into the mix, things get interesting. The one major flaw with electric bikes as of right now is charging them.
Sure, a 48V battery isn’t going to take ages to charge, but what if you don’t have a lot of time in between commuting? Let’s take a look at that.
What is a Solar Powered Bike?
A solar powered bike is exactly what you would expect: an electric bicycle that uses solar power as its primary energy source.
We say primary, not exclusive. There’s a misconception that solar powered bikes cannot be plugged in and charged traditionally, but that’s still completely possible.
These bikes use solar power to keep the motor running, although this is something that can take up quite a bit of power. It depends on whether you’re using pedal assist or full throttle, but either way, solar power has come far enough with PV panel efficiency ratings that this is possible.
If your bicycle primarily runs off of solar power with an occasional old-fashioned wall plug-in charge from time to time, it’s essentially a fully solar bicycle.
You can’t account for those days with little to no sunlight, but thankfully, we’re going to cover everything you need to know about charge times, ideal weather, and everything else in this next section.
Is Solar Bike Reliable?
This really is the big question here: can you rely on a solar bicycle without using wall charging, or any other form of energy?
If you plan it out, you absolutely can. Let’s talk about some key features of any solar powered ebike that you need to know about.
Panels vs. Charging: A quick Google search will show you a ton of for-sale solar powered bicycles, but if you inspect the specifications of any of these bikes, you’ll quickly find that they merely have solar powered capabilities. An image search will show you bicycles with 6-foot-long panels being dragged behind them to keep the charge going. So, where’s the middle ground? There isn’t one, really. You can mount small panels to the back of your bicycle over the top of your rear wheel, but those aren’t going to be as effective as you think. You either have to choose a big panel and the commuting inconveniences that come with it, or a smaller panel with less power. This is important to note, because you can get a 22.8% efficiency rating panel for either scenario.
Dual Motor vs. Single Motor: A single motor electric bike isn’t going to use as much energy in a single go. Without proper planning and knowing when to kick the throttle versus when to let it glide and just ride the momentum, you end up risking burning through a dual motor or dual battery setup. Dual motor bikes can operate on solar energy, but it will minimize the amount of time you have to ride during a single charge. It should be noted that for maintenance purposes, a dual motor bicycle can operate with one motor in the event that the other goes out, so if this will be reliable and speedy commuting for you, this isn’t a bad idea.
Use During Adverse Weather: If you’re not getting a lot of direct sunlight, whether it’s a cloudy day or you’re simply riding through a lot of shaded areas, you’re not going to get 100% intake efficiency for your panels. Intake efficiency doesn’t mean conversion efficiency, as to say how much sunlight converts to direct electrical energy, but the more panel space you have exposed to direct sunlight at all times, the better.
Battery Capacity: The battery capacity will dictate a lot of things. For one, a higher capacity means you’ll have increased times between charging, but it also means that you won’t be required to charge it as often, or at least you’ll be able to go through a cloudy day here and there without it ruining your commute.
Now that we’ve covered some of the different ways you’ll have to determine whether or not solar can be reliable for you, based on conditions, let’s talk about it as a power source without all the restrictions and thoughts that go into it. Can solar power be enough to sustain an electric bicycle, and for how long?
Yes, it can sustain an ebike. Whether you have a high capacity battery or not, solar panels can replenish your bicycle. There are ways to improvise, especially if you’re a commuter.
Additional Panels: For stationary use, you can hook up additional 5V PV panels when your bicycle is not being operated. Make sure your throttle is off and the bicycle won’t be mistakenly used by anyone. This also depends on your inverter and if it has the capacity to allow for extra panels. If this is an option, it’s a great way to boost effectiveness without carrying around an enormous panel.
Safe Charging Space: As long as you check the battery and don’t overload it, you can leave your bicycle in a safe space (such as an atrium in a place of work or your own backyard) and leave it hooked up with those additional panels. You’ll get plenty of sunlight and be able to charge up quickly.
Turn Off Pedal Assist: Unless you’re going to be super late for work, there are times where you may need to turn off the pedal assist so you aren’t using any of the battery. This is something that shouldn’t happen often, but if your commute is long, you may run into this a few times as the battery naturally begins to degrade after X amount of charges (usually somewhere in the 200-300 range).
The main reason that solar powered bicycles may not be reliable to some people, as you’ll find with horror stories on the internet, is because they don’t have a mindset that completely wraps around the idea.
The idea of renewable energy powering your bike is great, but you have to be proactive about it, especially given the long charge times. It’s reliable, you just have to be responsible enough to keep charging in mind.
How Does it Work?
There are two different ways that solar powered bikes work. Both are relatively similar, but one of them is a leap ahead of where we’re currently at with most solar powered cars, so it’s important to note the differences.
1. Solar panels are secured and houses on the frame of a bicycle. Photovoltaic panels ingest sunlight and convert it to electricity through an inverter, and the inverter sends that electricity to a battery housed on the bicycle.
From here, the energy is deposited and stored for later use. This is an important distinction, because the energy cannot be fed directly to the motor from the battery and be used in real-time as it’s being harvested.
So your battery will only actually charge while you’re not moving, since the battery is already operating to support the motor. If the bike is stationary, it will absorb solar energy and store it for later use. This is the first way that a solar bike works.
2. Some electric bicycles do charge while riding, although these are expensive and relatively new (Oct. 2018-ish), so they’re not widely distributed. It was done more as a stunt to see if it was even possible, and we’ve seen this implemented into some Tesla vehicles such as the Cybertruck.
It’s a tricky thing to do, and expensive as you need a different system than your standard 48V battery in your bicycle, but it’s an option. However, this is not a make-or-break mechanic for ebike users. Not by a long shot.
For the most part, you’re only going to receive scraps of energy while riding even if it were an option, so leaving your bike stationary in direct sunlight will often yield a better return on energy.
Solar Powered Future
We all know that solar power is going to dominate the future. It’s not ahead of dirty energy yet, but it’s growing and renewable, and the majority of people are finally starting to see the benefits.
Utilizing solar energy to finally cut the cord of at-home non-renewable energy sources (if you haven’t converted to a fully solar home yet, that is) is a big step in energy independence.
Solar powered bikes are effective, and while you need to wish for sunny weather sometimes, they’re going to get you from A to B without having to wait too long.
Ready to make your investment in your own energy future?
Noel Joseph has been in the world of motor vehicles for a long period. Currently, he is enthusiastic about Electric & Hybrid Motors and is an independent researcher. He advocates for a clean and sustainable future and envisions utilizing his years of experience in mechanical engineering. His new venture here at CompactPower.com is to organize and simplify knowledge on Electric vehicles. He wants to build a space where people can talk about EVs and associated technologies with freedom.