In the earlier article, construction of a small 5W day lamp was described. Here, how to make a high power solar day lamp is described. Apart from providing more light this design also offers following advantages:
1. 10% more light.
2. For increased power output, current still remains same as that for 5W version. Thus it still uses the same cheaper cable.
3. Improved construction, which provides better light reflection and safety to LEDs from damage.
Step 1: Material required:
2. Wooden batten
3. Wood screws 0.5” long
4. Plastic or fiber washers 3 mm inner diameter
5. 23 White LEDs 1W rating
6. 3 Way terminal strip and mounting screw/nut.
7. Four Solar PV panels of 12V 5 W rating (OR Two 24V 10W panels)
Please see the earlier article which provides step by step guidelines for making the LED array. Only different here is that we are making a bigger array with 23 LEDs.
Step 2: Circuit Diagram:
It consists of 23, 1W white LEDs (LED1 to LED23) connected in series. A current limiting resistor of 33 ohms 2W rating is connected to the LED array. Four solar PV panels of 12V 5W rating are connected in series as shown in the figure. The positive terminal of PV array is connected to the resistor and the negative terminal of the PV array is connected to the cathode of LED23.
Step 4: Improved Construction
Step 7: Final Integration
Step 9: Multiple LED arrays
This will provide light equivalent to 3 tube lights. The advantage of this circuit is that, it needs less wiring, as, only one cable needs to be routed from the PV panels to the inside of the building. This wire should support current drawn by 3 LED arrays (about 1 amp). Inside the building, each LED array can be connected in parallel by using thinner wires. By increasing power rating of the PV panels, we can connect more LED arrays in parallel.