Solar panel for charging

[Pard]

Anyone try to rig up a solar panel to charge the batteries while riding?

 

 

Thinking about an ultra long ride across the desert.

 

 

How cool and ambitious would that be?

 

https://www.reuters.com/article/us-race-australia-solar/solar-cars-begin-race-across-australian-desert-idUSKBN1CD04Y

 

Some discussion on the topic in this previous thread:

 

 

Edited November 10, 2017 by Pard

[esaj]

I think this has been discussed at least once before (in addition to the topic you linked), the basic problem is that the efficiency of current solar panels is relatively low (<20%, typically something like 10...15%?), meaning you'd need a relatively large panel to charge while riding. Or even if you'd charge only when stopped, you'd need something like a 1m² (around 10 square feet) panel to get any meaningful power and extra parts to pump up and regulate the voltage (that also have efficiency below 100%)... of course if it's okay to stick around for a couple of days to wait for it to charge, then it could work with smaller panels too 

If I recall correctly, the direct sunshine has about 1400W of power per square meter (1m² ), less when it's shaded. Assuming that the panel was one squaremeter and had 15% efficiency, the power output from the panel in direct sunlight would be around 1400W * 0.15 = 210W. Pretty close to what the usual chargers are? If the switching circuitry to pump up the voltage + regulation had a good efficiency of about 90%, the charging power output would be around 190W. Now, to charge for example 840Wh battery, that would mean 840Wh/190Wh = 4.42 hours, and that's assuming that the sun is shining and you're not using the wheel at the same time. Still, not saying it couldn't be done, but wielding a 1x1 meter -panel on your back with the charging electronics while riding doesn't sound that practical to me    Maybe some kind of foldable panel that would fit in a backpack and you could spread out when stopped?

EDIT: Glancing quickly through some panel weights, a 1 square meter panel weighs around 10kg (23 pounds).

Edited November 10, 2017 by esaj

[Pard]

5 minutes ago, esaj said:

I think this has been discussed at least once before (in addition to the topic you linked), the basic problem is that the efficiency of current solar panels is relatively low (<20%, typically something like 10...15%?), meaning you'd need a relatively large panel to charge while riding. Or even if you'd charge only when stopped, you'd need something like a 1m² (around 10 square feet) panel to get any meaningful power and extra parts to pump up and regulate the voltage (that also have efficiency below 100%)... of course if it's okay to stick around for a couple of days to wait for it to charge, then it could work with smaller panels too 

If I recall correctly, the direct sunshine has about 1400W of power per square meter (1m² ), less when it's shaded. Assuming that the panel was one squaremeter and had 15% efficiency, the power output from the panel in direct sunlight would be around 1400W * 0.15 = 210W. Pretty close to what the usual chargers are? If the switching circuitry to pump up the voltage + regulation had a good efficiency of about 90%, the charging power output would be around 190W. Now, to charge for example 840Wh battery, that would mean 840Wh/190Wh = 4.42 hours, and that's assuming that the sun is shining and you're not using the wheel at the same time. Still, not saying it couldn't be done, but wielding a 1x1 meter -panel on your back with the charging electronics while riding doesn't sound that practical to me    Maybe some kind of foldable panel that would fit in a backpack and you could spread out when stopped?

The foldable panel would be the way to go for the majority of the charging, but a smaller panel that could be worn could feed the battery some juice while riding, extending the range.  I will do some more research. 

 

Solar Bike:

http://www.maxun.cc/

 

Interesting idea .