Can you charge an electric bike with a solar panel?
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By Aimii | 24 June 2022 | 0 Comments

Can you charge an electric bike with a solar panel?

With the increasing gas price, more and more people start buying e-bikes. They use eBike in their daily commute, weekend mid-distance riding, or bike-camping trips. The e-bike does not replace the car. Sometimes you have to do longer trips. But it sure takes the sting out of high gas prices. What followed was the trend of charging the electric bike with a solar panel. Can a solar panel charge an electric bike, how can it charge, and is it worth buying a solar system for that? Let’s talk about it in this article.
 

Can you charge an electric bike with a solar panel?

Yes! You can charge your e-bike with a solar panel. Just need to figure out what wattage of solar panels to charge the e-bike battery. And connect panels to the components like a charge controller, power generator, or inverter. Solar panels can’t charge a large-voltage device directly.
 
A typical e-bike battery is around 500-700 Wh, 36V, or 48V. In that case, you would need large-size panels. In ideal conditions, it takes 6 hours of sunny weather for a 100W panel to charge a 500W battery that is discharged near zero. The average sun hours in the United States is 4-6. Most people ride back with a partially discharged battery instead of a completely empty one. If you ride an eBike only for commuting, a 100W portable solar panel is enough.
 
As we know, weather conditions, dust, and other variables could cause the total solar output to reduce by approximately 20-30%. For a 48V eBike battery, you would need two 100w solar panels. With two 100W panels, you can get 110W of input power during the worst of conditions (morning light, partly cloudy, etc) and over 150W in good conditions.
 

How to charge an electric bike with a solar panel?

As mentioned above, the solar panel cannot be connected directly to the battery of your eBike. It is operated with a set-up, which assists with the collection, transfer, and output of reversed solar energy to the battery. In that case, there are three typical ways to solar charge your electric bike.
 
The most efficient way - use a charge controller (MPPT)
Connect your solar panel to the controller. Then connect the controller to your eBike battery. The controller modulates the high or low voltage issues when direct charging.
This is the most efficient way. The least energy is lost during the charging process. And it is lightweight relative to other methods. But it doesn't work for many off-the-shelf electric bikes.
 

The way works for all eBikes - use an inverter and 12V battery

It uses the charger included in the eBike. Stores the solar energy from the panel in a 12-volt battery. Here a charge controller is also needed. Then uses an inverter to convert the DC from the 12V battery into AC for the e-bike charger. Your AC eBike charger will convert back to DC to charge the e-bike battery. It works for all e-bikes. But this conversion produces a huge efficiency loss, 20-50%. The 12V battery and inverter are also extra weight and cost. 
 
Some people suggested using the inverter directly to connect the panel to the e-bike charger. But we don't think it is a good way. Without the voltage moderation by a controller, just running an inverter may not be safe.
 

The simplest way - use a solar generator

The solar generator contains all the assistant accessories you need. It has a built-in solar charge controller to regulate the input solar energy, a battery to store the energy, and an inverter to convert it to AC power. So it works with all eBikes.
 
Just need to connect the solar panel to the generator daytime to store the energy, then you can charge your eBike at any time and location you want. Its very convenient. Of cause, the solar generator is expensive and less efficient. And there is some noise when it works, especially at night.
 

For the detailed installation steps, you can read the article from Footprint Hero, written by a DIY solar power projects expert Alex Beale. He also mentioned some other DIY ways there.

 

Is it worth buying a solar panel to charge eBike?

If you buy a solar panel only for the purpose of solar charging your electric bike, this isn't a money-saving option. A quick calculation shows charging a 500 watt-hour battery might cost $0.07. Your solar charger set-up may cost at least $500. To get back the cost of the set-up, it would take 7143 charges. If one charge per day, it is equal to 19 years!
 
What does make sense is solar energy allows you to keep up a minimum reasonable lifestyle when the commercial power goes down for more than a few hours. Have enough energy to recharge your smartphones and to give you light at night. And if you need that eBike during a power outage, you might have enough energy storage for it.
 
Basically, solar energy is great to have for emergencies. That's why we recommend you to buy a 100w portable solar panel and a 500w portable solar generator. This might be a good "in-between" while offering flexibility with other electrical needs, and minimal DIY experimentation.
 
If you go camping frequently during the year, adding a portable solar panel to your camping would be a very good idea. Or you would be dependent on charging your batteries overnight at the campsite. And typical charge for hydro at campsites is around USD $5-$10 per night.
 

Conclusion

Charging an electric bike with a solar panel is definitely do-able. If you are a prepper and often go camping/fishing multiday trips, a 100w portable solar panel would be a good investment. The benefits will definitely ensure your investment pays off.
 

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