Solar trailer build

[matthewslack]

A learning day-today. Dull start, charging at 16W, with brighter skies forecast for later.

After two days of taking not much out of the Shimano battery, although my solar battery is full I only have about 200Wh of it available before I deplete the Shimano. So limited range, and so reason to delay start and reduce time riding before the promised brightness arrives.

A generic system would not have this issue. If I had all the combined capacity of 800+Wh available, I'd be on my way all ready.

Today's tactic is to ride gently on the flat early part of the route, using only 50 to 70W, with 20 to 50 coming from the panels. That way I can eje out 50 miles without eating into Shimano, and hopefully sneak into the sunshine.

I will try out the Lancaster canal towpath cycle route from Lancaster to Kendal, which will slow me down, save energy and add to my knowledge.

 

[guerney]

I will try out the Lancaster canal towpath cycle route from Lancaster to Kendal, which will slow me down, save energy and add to my knowledge.

Prepare for rock n roll! Canal tow paths can be rough... not all Councils maintain them well.

 

[matthewslack]

Prepare for rock n roll! Canal tow paths can be rough... not all Councils maintain them well.

Very much the case here! First 10km is mostly worn out tarmac, almost unrideably bumpy, now reverted to grass and smooth narrow lane of mud.

Fine if not in a hurry or fully suspended, so will do for today, but in a rush I would be back on the road already.

 

[guerney]

Very much the case here! First 10km is mostly worn out tarmac, almost unrideably bumpy, now reverted to grass and smooth narrow lane of mud.

Fine if not in a hurry or fully suspended, so will do for today, but in a rush I would be back on the road already.

The worst canal towpath I ever traversed was made with poured concrete, which had broken up as big thick blocks at random angles with cravasses in between... no doubt a MTB with large travel suspension forks would have negotiated that ok, but not my bike! Which is why I avoid canals, despite their advantages.

 

[matthewslack]

The worst canal towpath I ever traversed was made with poured concrete, which had broken up as big thick blocks at random angles with cravasses in between... no doubt a MTB with large travel suspension forks would have negotiated that ok, but not my bike! Which is why I avoid canals, despite their advantages.

I am persisting in the interests of science!

I am down to about 7mph average, but it is very scenic.



I had not realised the canal is not navigable all the to Kendal. Three cheers to Lancaster Canal Trust for working away to change that.

 

[sjpt]

The towpaths under the bridges are often very narrow. Did you manage them OK? The one in your picture looks wider than some. Perhaps that canal was built for fatter horses than the Grand Union?

 

[guerney]

The towpaths under the bridges are often very narrow. Did you manage them OK? The one in your picture looks wider than some. Perhaps that canal was built for fatter horses than the Grand Union?

I fear he's been trampled by a Shire horse

 

[matthewslack]

The towpaths under the bridges are often very narrow. Did you manage them OK? The one in your picture looks wider than some. Perhaps that canal was built for fatter horses than the Grand Union?

Tight, but manageable! The stone bridges are also just ok, I ride on the edge of the big stones next to the water very gingerly!

The bridge with the lorry was the M6, so different era.



I have just had a conventional mechanical failure, so charging in Keswick Booths sunny carpark corner before a night in town and a search for a good bike shop.



Failed gear cable nipple. I need to stop thinking of this bike as new: it may be only 10 months old, but on Dunmail Raise Bah Tat it just hit 5500 km. Time to improve my spares kit.

 

[matthewslack]

End of day 3, 111km, 69 miles, 927Wh used including 76 late on from the Shimano battery up Dunmail Raise, and then at max torque in unsuitable gears after the cable failed. Generated 781 so far, a little bit of evening sun still to come. Again, a product of late energy demand and small buffer capacity, as good conditions earlier in the day kept battery full until the hills approaching Bowness, of which there are more than I remembered!

An expensive day at 8.4Wh/km, 13.4Wh per mile.

Tomorrow a repair job and onwards to the Border.

 

[matthewslack]

Day 4 started with a cable replacement in which my toolkit of one Allen key and a small screwdriver was fully utilized . Easy once the short broken end was jiggled out of the shifter. Great help and part from the ebike specialist bike shop in Keswick, just by Booths. Impressive fleet of Haibike hard 7, Kalkhoff step through and various full suspension mountain bikes available on day or half day hires.





The proper riding started just before 10am, a good first hour going west of Skiddaw then brutal headwinds and the busiest road yet to Carlisle. Must have been 500 vehicles an hour on that section. Doing my usual stop at every reasonable pull-in to let them past, but so many! Often the vehicle catching me already had its own tail, one tractor with muckspreader had 30+ cars behind. The first 10 knew about the tractor. The rest seemed to think me waiting on a layby was the cause of their lost minutes. Life is so unfair!

That morning session is my highest ever recorded Wh/ mile: 564Wh for a mere 52km, 10.8 per km, 17.5 per mile. Rewarded by a beautiful lunch spot in Carlisle under new copper beech leaves and blue sky.





Much easier going in the afternoon, scrambled data after letting the data logger batteries get to low, but back to normal range.

An hour charging in a layby after a long section of tree screened road, and another session at camp mean after four days the solar battery is full. The Shimano is on two bars and with the good forecast should make it home this time.





Total distance today 118km, 73 miles, and only 156 miles to go according to AA route planner. Three days available if I need them, so looking good.

 

[matthewslack]

Day 5, long day but short writeup!

95 miles, 929Wh consumed, 900 generated. 71 miles to go. COVID may have gone, testing in the morning.

 

[AndyBike]

You've certainly proven that a trailer solar panel set up is ideal for long range touring. Its just such a large size. Is there any way of allowing it to fold when not in use, or is it always needed to be in use to trickle charge as you go* ?.

*Sorry, I haven't read the entire thread, so may have missed the part on how long in use it takes to supply enough of a charge to replenish the batteries enough for the next days leg.

 

[Nealh]

Proving it can be done a great effort Matt, as Andy has said though the size and array of solar panels needed is quite large. We know better wattage panels can make the array smaller but as you have said at the start or on another thread, the price is quite high.

 

[guerney]

Arriba! Lightweight and flexible ultra-efficient solar panelled sombreros!

Ultra Efficient ‘Tandem’ Solar Panels Ditch the Silicon to Absorb More of the Sun's Spectrum With Less Energy

German scientists have published details of their new solar panel, calling it the world’s most efficient of its type, using a wider spectrum.

www.goodnewsnetwork.org

...or glued onto

'Night solar panels' that work in the dark could be just as productive

The special solar cells work the same as their daytime counterparts - but in reverse.

www.euronews.com

Could ‘hot carrier’ solar cells break the theoretical efficiency limit?

Up to 50% of the energy absorbed by a solar cell is lost as heat. Scientists are now developing a third generation of “hot carrier” solar cells that take advantage of this heat, potentially breaking the Shockley-Queisser limit of silicon-based PV.

www.pv-magazine.com

Trina Solar achieves 25.5% efficiency in n-type TOPCon solar cell

The result was confirmed by the National Institute of Metrology of China. It was achieved with a cell size of 210x210mm.

www.pv-magazine.com

Scientists Achieve Record Energy Efficiency for Thin Solar Panels - EcoWatch

Scientists from the University of Surrey and Imperial College London have achieved an increase in energy absorption in ultra-thin solar panels by 25%, a record for panels of this size.

www.ecowatch.com

 

[matthewslack]

Proving it can be done a great effort Matt, as Andy has said though the size and array of solar panels needed is quite large. We know better wattage panels can make the array smaller but as you have said at the start or on another thread, the price is quite high.

Yes, it will not be the answer for many journeys, and not even for my own shorter trips. But the idea of heading into the wilds or to those long, one way roads in the Highlands on my regular 7 day offshifts is now something I can do without worry.

I'll be thinking about if not smaller then lighter, and better matching of output to demand, and better instruments, but they can wait until I'm back from this trip.

The panels and electronics is only a third of the empty trailer weight. I'd like that to be under half.

 

[matthewslack]

Today starts dull, with promise of brightness nearer the coast. But 40 miles of inland roads with moderate hills before that, so no rush to roll. Still positive for COVID, but the nasty cough has gone.

First look out at 06:30, panels generating nothing. Now at 08:10, 30W, so it will be at least 50% battery power to begin with. I have had such a good run of sun, haven't had to really think about optimization on this journey so far, except for the best charging angle during breaks.

More data on yesterday: it was a good example of how a good solar day is organised.

First thing, before the off, static panels pointed as close to the sun as possible to get battery as full as possible. Not needed this time, as already full from night before.

Early start in blue sky but low sun angle, so demand higher than generation for 20 miles to first stop. 8am to 10am, first 23km used 242Wh, generated only 91. Technical timeout when the rack squeak returned, which turned out to be the other side broken! So my rack is hanging on by the two top bolts, a small block of redwood floorboard, lots of insulation tape and about 7 cable ties!



Next 10km used 85, generated 117. Short break at Abingdon services, generated 30.



Then the prime hours, from three before to three after solar noon, in BST from 10am to 4pm, cruising in full sun, high assist level, with an energy surplus. Can't read my own writing for the numbers there, but left lunch break at 3pm after a nap with full 41V battery.



Then late afternoon, after data logger reset, 143Wh used and 60 generated in last 26km of the day as cloud came over late on Finished with 38V battery.

I'll put up some data files assuming that they have landed on the SD card in good shape when I get home.

But for now, onward into the 71 miles!

 

[matthewslack]

A gentle grey morning has become a glorious sunny lunchtime with all worries about energy consumption put well and truly to rest. I stopped every few km and recorded the seconds elapsed, voltage, Wh used and generated, and km to illustrate less than perfect conditions.

The data logger was started before I set off, 1676 seconds is start time.

1676 secs, 39.4V, -2Wh used,12Wh generated, 5792km.

3464, ?, 40, 50, 5800
5050, 38.2, 86, 69, 5808
5721, 38.3, 101, 81, 5811
Break
7018, 39.3, 99, 116, 5811
9212, ?, 131, 140, 5817
11280, 38.4, 187, 183, 5028
12100, 38.3, 208 202, 5832
13790, 37.0, 305,240, 5840
14630, 38.6, 347, 270, 5844.
Lunchtime in the sunshine.
17290, 40.5, 344, 417, 5844.
Still lunchtime!



Until the hills up to Crianlarich, slow speed and level 1 assist kept gen and use similar, and the use of level 2 on the hills is very obvious. The speed of battery replenishment when 7.5amps becomes available is also very noticeable!

I have yet to ride an entire dull day, but I can already see that in level 1 I can expect 60 miles of gentle progress without depleting the battery, and with a bigger battery I would be able to overcome a whole dark day with no overall effect on a trip.

More will be learnt in the summer.

I have new techniques for bike path barriers to report:



Remove one wheel, uncouple, roll through on the edge of the other wheel. In these specific barriers on the Loch Lomond ' too nice to miss' Firkin Point section, I reverse into the box and then back out the other side. Four sets in a few miles, but the old A road down by the Loch shore instead of the busy new road is the reward.

 

[jimriley]

When you mention power levels, how many steps do you have between top and bottom. I currently have bbs01b set to 9, could be 3 or 5.

 

[matthewslack]

When you mention power levels, how many steps do you have between top and bottom. I currently have bbs01b set to 9, could be 3 or 5.

I only have three, and don't use the highest! This is one of the compromises that comes with adapting a Shimano Steps equipped bike.

Level 1 gives me good basic assistance on the flat with no headwind, and an easy cruise at 22 or so kph with touring all up weight of about 130 to 140 kg. Level 2 and use of the gears gets me up 1 in 6 for short sections, 1 in 8 unlimited distance, and deals with any headwind. But too expensive on energy for continuous use unless a blue sky.

I need a level between the two for use on bright days to use all the solar generation, which would push cruise speed all the way up to 25kph.

So far I have failed to get the app to connect to the bike, so unable to change the levels

A conversion with a KT controller offers many levels. I hope to play around with the OSF and torque sensor with my old MTB and TSDZ2. But for now I can live with what I have.

 

[matthewslack]

Nearly home. Wasn't going to make the ferry so had an easy day and left 18 miles for the morning.

92km, 57 miles, total of 573Wh used and 651 generated. Seems fitting to hit exactly 10Wh per mile!

The different route options compared to the outward journey have added about 64km, so overall looks like being 1468km, 912 miles for the round trip.