How to improve solar charge efficiency ?

One important area for improvement is how to minimize the losses/inefficiencies around the energy storage on the solar trike.

After few months I finally wanted to start to look in particular to this aspect: when the solar charge goes into the battery there is an efficiency factor roughly of 95%

(reference http://large.stanford.edu/courses/2010/ph240/sun1/)

This means that when I charge 100 Watts from the solar panels, only 95 Watts are stored inside the battery.

In the same way, when the battery send 100 Watts (= discharge) to the motor, only 95 Watts are effectively usable

This means that from 100 Watts charged from the panel I can only use 100W x (0.95×0.95) = 90 W, thus wasting 10 watts (10%!).

For this reason I have been looking into a way to “bypass” the battery in order to send directly to the motor the energy from the solar panels

Here on the right is the standard way I have been using the battery so far:

  • the solar panels charge the battery

  • the hub motor is fed from the battery

And here on the right is the alternative scenario I have tested and that works as follows:

  • the Battery switch is = OFF

  • the energy from solar panels goes DIRECTLY to the hub motor completely bypassing the battery

Here is the test I have done.

It demonstrates that when the battery switch is set to OFF then the solar panels DIRECTLY feed the hub motor.

 

We can take advantage of this solution in different ways:

1) – in case the battery is FULL, I can use directly the energy ( which otherwise would be wasted) from Solar Panels

Ideally this solution would be even better with an AUTOMATIC switch that connects DIRECTLY the Solar panels to the hub motor when the battery is FULL.

2) – when enough solar energy is available I can decide to send it DIRECTLY to the motor ( instead of using solar panels to charge the battery ).

 

This Post Has 2 Comments

  1. The question of this post is interesting. However, it seems to be really interesting in case of strong sunshine, so that enough amps can be sent to the engine.

    1. Hi, you are right!
      If I don’t have AT LEAST 100W coming from the solar panels, then this solution is not so interesting
      This is why I think it would be nice to develop a solution where the switch is AUTOMATICALLY set depending on a given condition:
      EXAMPLE: IF solar charge is GREATER than 100W AND battery is FULL, THEN set the switch to OFF (=direct charge from solar panels).
      But the solution is more complicated than that: in fact if I am using 300W (going UPHILL) and there are “only” 200W coming from solar panels, then the switch should probably not be set to OFF…
      For the moment I will just use this solution with a manual selection of the battery switch 🙂
      Thanks!

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