A solar light works with a few key components: a solar panel, a photo sensor, a battery, a light source, a control board, and the frame.
The main component, the solar panel, works on the principle of converting light into electricity using two layers of silicon: one positively charged with a boron and one negatively charged with phosphorus, which is photosensitive and will in high concentrations glow in the dark. When the negatively charged plate is struck with sunlight, the electrons flow and just like that, electricity is generated. The electricity travels to the battery where it is stored for later use.
The control board is a basic mechanism that, when triggered by low light conditions by the photo sensor, switches the light on. It works on the principle of the transistor switch: when a small current is run though it, it causes a larger current to also run though the transistor, which is the basic switch function. The control board is usually made of the simplest types of transistor chips, simpler even than what you find in dollar store calculators. Even an ancient tube transistor could do this job. With some books and some patience, this level of circuit board is something the average home DIY enthusiast could figure out, although for long life and size considerations, professional parts are always best.
The photo sensor is actually just a micro solar panel. When its output falls below a certain level, the electronic board recognizes that it is now dark outside.
The battery, one of the most crucial components, must be a durable rechargeable unit and sized specifically for the power requirements of the unit on an average day. This will ensure healthy battery life by coming as close to a full discharge as possible each night.
The frame is an often overlooked but very important consideration, because, for example, a glass cover will outlast a plastic solar panel cover and won’t discolor with age. A metal or heavy ceramic frame will outlast cheap plastic molded versions.