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by jryhjythtr 1318 days ago
>Mine has a solar panel over the cargo bed and never needs charging

Interesting - what's your average daily mileage? I'm relatively familiar with the power requirements of EVs, and large-scale solar installations. I have no idea what kind of average charging power a small solar panel provides!
2 comments
Schroedingersat 1315 days ago
Fairly low mileage but it also spends a fair bit of time inside. Most miles go on the unpowered one as the cargo bike (actually a rear-steer tricycle) is for large cargo.

It's a nominal 200W panel (older fairly inefficient monocrystalline, big enough for a small sunshade which is its main function) and will fill the 1.1kWh battery in about a day (in a near-optimal climate), or two if the weather is meh. Before I mounted it on the trike I could get ~100-150km before plugging it into the panel on flatter ground or about 20-30km on a route with several big hills (12% grade) and a heavy (50kg bike + 50-100kg cargo + 75kg rider) load.

The trike is pretty speed limited by handling though (20-25km/h) and it takes very little effort on the flat to keep it above the 25km/h speed limiter. On flat ground or shallow hills (1-2%) during the sunny part of the day (9-3) I can't use more power than the panel provides without going up hills because of the speed restriction.

I'd imagine on a bakfiets in an area where 32km/h limiters were allowed you'd get about 30-50km depending on the terrain.

Some back of the envelope:

Consider this: https://www.bakfiets.com/elektrische-bakfiets/cargobike-clas...

A less ghetto lid than my arrangement would be 0.63m^2

This would fit okay as a lid: https://www.solar4rvs.com.au/sunman-earc-100w-flexible-solar...

a little narrow and would hang over the edge a little.

Assume it's about 45 degrees from optimal (70%) and that you're getting the average irradiance from somewhere like denmark (1000kWh/yr). You'll get about 71kWh/yr. Cut off 7kWh for charging loss so 62kWh.

A typical bike battery is 500Wh, so 120 charges or 1 full charge every 3 days.

A charge might get you 20km or it might get you 90km, but for a typical rider with moderate hills who puts in a 40-60W contribution (same effort as walking) and doesn't want to risk grinding home the last 10km on a cloudy day, a reasonable ballpark is 50km/day. So you're looking at ~15-20km (but you'll need to charge it in winter), or maybe up to 5x that (and decent range even in winter) if you think very carefully about parking, live in a better climate for solar, and do 25 rather than 32.

link
Schroedingersat 1315 days ago
Fairly low mileage but it also spends a fair bit of time inside. Most miles go on the unpowered one as the cargo bike (actually a rear-steer tricycle) is for large cargo.

It's a nominal 200W panel (older fairly inefficient by new standards monocrystalline, big enough for a small sunshade which is its main function) and will fill the 1.1kWh battery in about a day (in a good climate of 1800kWh/yr), or two if the weather is meh. Before I mounted it on the trike I could get ~100-150km before plugging it into the panel on flatter ground or about 20-30km on a route with several big hills (12% grade) and a heavy (50kg bike + 50-100kg cargo + 75kg rider) load.

The trike is pretty speed limited by handling though (20-25km/h) and it takes very little effort on the flat to keep it above the 25km/h speed limiter. On flat ground or shallow hills (1-2%) during the sunny part of the day (9-3) I can't use more power than the panel provides without going up hills because of the speed restriction (ie. It gains charge).

I'd imagine on a bakfiets in an area where 32km/h limiters were allowed you'd get about 30-50km depending on the terrain.

Some back of the envelope:

Consider this: https://www.bakfiets.com/elektrische-bakfiets/cargobike-clas...

A less ghetto lid than my arrangement would be 0.63m^2 or up to 150W nominal if it was a perfect fit and a high end panel.

This would fit okay as a lid: https://www.solar4rvs.com.au/sunman-earc-100w-flexible-solar...

a little narrow and would hang over the edge a little, not far offour benchmark.

Assume it's about 45 degrees from optimal (70%) and that you're getting the average irradiance from somewhere like denmark on a meh week (1000kWh/yr) where you only think carefully about your parking spot at home. You'll get about 71kWh/yr. Cut off 7kWh for charging loss so 62kWh.

A typical bike battery is 500Wh, so 120 charges or 1 full charge every 3 days.

A charge might get you 20km or it might get you 90km, but for a typical rider with moderate hills who puts in a 40-60W contribution (same effort as walking) and doesn't want to risk grinding home the last 10km on a cloudy day, a reasonable ballpark is 50km/charge. So you're looking at ~15-20km/day (but you'll need to charge it in winter every week or so), or maybe up to 5x that (and decent range even in winter) if you think very carefully about parking, live in a better climate for solar, and do 25 rather than 32.

link