My encounter with the solar bike
I had a long experience of cycling when I was tempted by the solar bike, after following on the internet the adventures of the participants in The Sun Trip rally. But the immediate interest was rather the trip of the following summer. In 2020 for the Sun Trip France, I was very tempted but I could not be ready in time; So I prepared for Sun Trip Europe the following year. Without any experience of electric bikes, I chose proven options: electrification of my travel bike, with Guillaume Devot, and purchase of a Sun Travel trailer (used).
My bike
Finally I preferred to refurbish my previous travel bike, a Gary Fisher mountain bike bought in Santiago (Chile) and which had ridden the Carretera Austral, Iceland, New Zealand. The additions: an unsprung aluminum fork (to be lighter), a Cane Creek suspended seatpost (in electric bike we ride faster so we are more shaken), a new 10-speed transmission… Long story short, I only kept the aluminum frame. I kept the dynamo lighting, which works without battery, you never know… The wheels are 26 inches. The weight of the bike is about 15 kg. I use Schwalbe Marathon Plus tyres (26 x 1.75) for cycling.
The electrical system
Very classically, I followed Guillaume's proposals:
- 9-Continent RH212 direct drive rear wheel motor, 1000 watts (6.5 kg)
- Base Runner Controller
- 48 volt battery charging 21 Ah or 1 kWh (4.1 kg) in a waterproof frame bag
- Cycle Analyst V3 solar for control of the whole.
The trailer
I chose a Sun Travel trailer equipped with 2 panels (240 Wp in total). It is a single-wheel trailer that attaches to the seatpost, it drives like a charm. Trailer weight: 21 kg (11 kg for mechanics; 10 kg for aluminum panels and support frames, and solar chargers (there are two: one for the 2 panels on the trailer; one to be able to connect a 120 Wc Sun Travel suitcase). Cost of the set: The frame of the bike was largely amortized; I spent about €700 to renovate everything else on the bike. Then the electrification was done for 2190 €; The used solar trailer cost me 1450 €.
Feedback
I used this bike two summers: In 2021 for the Sun Trip Europe (Prologue from Lyon to Brussels; 1/2 Tour Brussels Lyon (about 750 km) then 1/2 Tour Lyon-Spain-Portugal-house solo (13640 km in all). I encountered few problems: mechanical breakage on the drawbar of the trailer (adjustment joint), adjusted by drilling and adding 4 bolts. Sealing problem on the solar charger after a strong storm: a reset was necessary. On the whole I was limited by solar capture, but, without any real time constraints, I never used my charger. The whole course being often flat the engine did not heat too much, except in the largest passes (Alps, Pyrenees, Sierra Nevada). The trailer fell several times when stationary and once while driving, without loss of functionality. I experienced a single puncture, on the trailer, whose tire I had not changed before the start (despite its apparent wear …); No punctures on the bike. The figure below shows the summary of this journey: for each day, the distance travelled, (in km) the elevation gain (m), solar production, (W.h) consumption (W.h, regeneration deducted). 
In 2022, I did the Sun Trip Alps: Grenoble – Bled – Lyon (about 2450 km). I had also brought a folding panel of 120 Wc, adding a load of about 3-4 kg. But the course much more rugged (slopes greater than 15% from the start!) caused the engine to overheat, and even the engine power connector that had to be by-passed on the side of the road, by a colleague tripper (using dominoes and "wago" connectors). Finally I got to the end. But I had to push several times…
Evolution
I am now considering several changes, with a view to participating in the Sun Trip Alpes 2023 (identical to the previous one but counterclockwise):
- Replacing the rear wheel motor (26 inches) with a motor in the trailer wheel (20 inches) to improve efficiency (direct drive motors are more efficient if installed on a small wheel for greater rotational speed). I remain attached to this type of engine to benefit from the recovery of energy in the descents.
- More battery capacity (from 1 kWh to 1.5 kWh at least) to be able to pass more passes in the same day.
- Improve the total power by adding a light motor (1 kg) acting by friction on the rear wheel (Gboost)
- Adding a solar panel at the front (about 120Wp), because increasing the storage capacity does not help much if I have to stop more often to recharge. I'm thinking about the optimal way to install it.