Because I am an electronic engineer I decided to buy a recumbent bicycle convert it to an electrical bicycle myself. I have designed all the electronic boards with exception of the motor-controller. Below is a schematic of the whole system electrical system:

PV panels : semi flexible solar panels (100Wpeak each) mounted on aluminium frame, source Ali-express

MPPT : this device boosts the voltage from the panels (~15V) to a higher voltage (~40V) for charging the battery. It also adjusts the current drawn from each panel so it will give highest possible output. (this is Maximum Power Point Tracking - MPPT). Each panel has a separate tracking circuit so if one panel is in the shade it will not start absorbing the energy from the other panel. The battery voltage is monitored closely to prevent overcharging the battery.

battery : 36V / 1.2 kWh lithium battery, see separate topic about the battery assembly

charging station : station provides 5V and 15V outputs for charging mobile devices like torch, telephone and laptop. See separate topic about this box.

E-controller : this programmable controller constantly measures the voltage and current flow from panels, battery and motor. It displays these values on a display in front 'the cockpit'. It also measures measures cumulative power for each day.  The E controller also contains circuitry for logging, remote control and alarm.

motor driver : Kelly

motor : Gearless hub motor in the rear wheel. 500 W, Brand: MXUS XF39 XF40. The motor has a large diameter for higher torque performance

throttle : a thumb operated throttle it controls the current to the motor.

brake sensor : the two handbrakes each have brake sensors. When just slightly pressing the handbrake the motor controller switches to regenerating mode. The kinetic energy is then converted into electrical energy recharging the battery. Only when brakes are pressed harder the brake pads are engaged.

cockpit : This device is connected to the E-controller with a serial connection. It serves a graphical user interface with pushbutton inputs from 4 buttons on the handle bar. It can display voltages, Ccrrents, power, distance and speed. The cumulative power (Wh) can also be displayed.

pushbuttons : 4 pushbuttons mounted on steer controlling the display and the rear light.