I am a high school robotics teacher (no formal engineering training) and I am taking a group of students to Kenya this summer to work with high school students there. The organization we are travelling with has asked us to help out with a side project at a small rural village that has no electrical power grid. They have said that most of the households have no lights in their homes but they all have cell phones. The problem is that along the equator days and nights are essentially 12 hours each all year long. This makes it difficult for students to study at night and for parents to work much after sunset. In addition, only a few individuals have the ability to charge phones which means others must wait in line for charging.
The proposed solution is a solar system for individual homes. I am trying to design something to test with the idea that the more we can purchase with the funds we have will mean we can help more families. Here is what I have so far.
- We are assuming that the system will have an LED light which needs 10.5 W and a USB port which needs 18W. I have drawn up a simple schematic for everything but the USB. I am not sure where the USB would go. I am thinking between the LED and the battery. I am also wondering if this product would work.
- I am also trying to calculate battery requirements. I have used the following formula to estimate storage capacity:
What am I missing with these estimates? Once I have this figured out, how do I calculate the minimum power requirements for the solar panels?
Best Answer
To answer one small piece of your question, the component you have linked in your question will not work in the circuit you have shown. USB power is 5VDC while your calculations show you're planning on a 12VDC system, so you can't just connect the wires directly. You will need to include a 12V USB Adapter similar to this item USB Adapter.
The azimuth of the sun and roof design are more about installation than component selection. The factors for selecting the solar panels would be the average or seasonal intensity and duration of the sunlight, and the power generation efficiency of the solar panels are the factors that drive the solar panel selection. You will also need to consider the charging efficiency of the batteries since some of the power applied to any battery for charging is lost.