If you are looking for a renewable energy project – Solar Power Module is a perfect addition to your motor kit!
Solar Power Module consists of powerful 6 V, 270 mA (1.6 W) solar panel, Schottky diode, bracket with double sided tape, wires and mounting hardware. It also includes a power switch for your motor. This module could be added to almost any motor kit available at our site. It provides enough power for them (except conventional motors) to work under direct sunlight; however the main purpose of the solar panel is recharging the batteries.
Here is the electrical diagram of the solar panel connection to the motor:
Under direct sunlight the solar panel generates up to 6 Volts of electricity with maximum current up to 270 mA. Diode protects the panel from negative current. Special Schottky diode is used as it has minimal voltage loss going through it (usually less than 0.2 V).
If the switch is in off position, and the voltage of the rechargeable battery pack is lower than the difference between solar panel voltage and voltage drop on the diode, the current flows through the battery recharging it. Recharging stops when the solar panel does not receive enough light as in this case its output voltage drops.
If there is no batteries installed the panel may provide enough electrical power for the motor to work under direct sunlight, however the rotor may need a slight push to start because the starting current through the electromagnet may exceed the panel’s output current.
If the switch is on and batteries are installed, both solar panel and battery may supply electricity to the motor (first who has a higher voltage; when they are the same both contribute).
This is a really simple solar panel addition. It is just a great first step into solar energy usage. If you are planning to use solar power for a long time (we are talking about months or longer) you need to take measures to protect the battery from overcharging that decreases its life. The solution is to add a current-limiting regulator. Some additional circuitry might be needed as well.
Because the charging current is not controlled in this setup we strongly advise against using lithium-ion batteries. If they are overcharged they might explode and cause fire. We recommend NiMH (Nickel-Metal Hydride) batteries. They are relatively inexpensive and provide good results.
See Assembly Instructions: Solar Power Module for instructions on how to add solar panel to your motor. You may also like an excellent article by David Cook from Robot Room that helped us a lot in creating the Solar Power Module and this page.