How Do Solar Lights Work? Types, Uses, and Environmental Impacts

Solar lights absorb the sun’s energy during the day and store it in a battery that can generate light once darkness falls. Like solar panels used to generate electricity, solar lights use photovoltaic technology. They can be used for a variety of indoor and outdoor purposes, from lighting streets to illuminating homes and gardens, and are particularly useful in places and circumstances where it isn’t possible to connect to a central power grid. 

How Solar Lighting Works

Solar lights use photovoltaic (PV) cells, which absorb the sun’s energy and create an electrical charge that moves through the panel. Wires from the solar cell connect to the battery, which converts and stores the power as chemical energy until it's needed. 

The battery later uses that energy to power an LED (light-emitting diode) bulb. The diode is a semiconductor that allows electrons to pass between its two points, creating electromagnetic energy in the form of light during hours of darkness.

LED technology generates light up to 90% more efficiently than incandescent and fluorescent lighting, making it ideal for solar lighting systems. Rather than burning out like a traditional light bulb, LED bulbs simply dim over time. But their typical lifetime is far longer than a traditional bulb: tens of thousands of hours versus the 1,000 hours of an incandescent bulb, or 3,000 hours for a halogen bulb.

Types and Uses of Solar Lighting

Solar lighting sales have taken off in response to the global demand for less carbon-intensive energy sources and as a strategy for increasing energy resilience in the face of extreme weather and other natural disasters that leave centralized power systems vulnerable. It is also helping to meet the energy needs of developing regions where connection to a centralized electricity grid is difficult or impossible. 

Solar lighting provides cheap, attractive, low-maintenance illumination for homes, businesses, and public infrastructure while reducing the environmental impact. When we think about solar lighting, there are two broad categories: indoor and outdoor solar lights. Here are a few of the many solar lighting uses.

Street and Parking Lights

Investment in renewable energy, energy efficiency, and other sustainable planning approaches have led to rapid growth in solar street lighting for towns and cities.

Solar-powered lamps provide cities with a cheap way to illuminate streets, sidewalks, and parking lots, creating better safety for pedestrians and drivers alike. They typically include a lamp post and fixture powered by a small solar panel array attached to the post. This makes each lamp self-contained and able to generate carbon-free electricity without requiring connection to a central grid and has the added benefit of reducing overall installation costs.

Traffic Lights

Solar-powered traffic lights are not only economical; they can save lives during power outages and in places lacking reliable electricity sources by ensuring consistent, uninterrupted operation of traffic signals. 

Solar Sign Lights

We sometimes take for granted the illumination of billboards, street signs, and storefront signs, but proper lighting is quite important for achieving effective signage. Solar sign lights provide a way for businesses and public services to highlight essential information while saving money on electricity. They come in a variety of brightness levels depending on the needs.  

Solar Floodlights

During and after a natural disaster or other circumstances that cause power cuts, solar-powered emergency floodlights can help crews make repairs under challenging conditions without the need for generator-powered lighting system. These powerful solar lights can also be employed in home workshops, garages, yards, and businesses that need extra security or stronger illumination. Some are security lights come with timers or sensors to ward off would-be troublemakers.

Garden Lights

Solar lights have become extremely popular for use in gardens, patios, and outdoor dining venues. They provide both safety and aesthetics, and come in a wide array of styles and products. 

Lawn lights can highlight attractive garden features like flower beds, trees, or sculptures. Pool lights illuminate water elements like swimming pools, ponds, and fountains. A string of solar lights can be stretched across a patio, porch or between trees to add a touch of festive ambience. Ground lighting along a walkway, driveway, or steps improves safety and provides an attractive design element. 

Solar Candles

Suitable for both indoor and outdoor use, flameless solar-powered candles and torches are a safe alternative to a real candle. Modern designs feature realistic flickering “flames” that resemble the real thing but avoid risk of fire and spilling messy hot wax. 

Solar Desk and Table Lamps

A solar desk lamp is a great accessory for a home office. For one thing, it's cordless and thus completely portable, which makes it possible to set up a remote workstation virtually anywhere, indoors or outdoors. Designs for desk lamps range from small clip-on book lights to sleek and sturdy tabletop varieties. Table lamps, meanwhile, create ambience as they produce illumination. 

Like other types of residential solar lights, some models come with a built-in solar panel while others must be connected to an external photovoltaic panel, but neither type requires direct sunlight. The energy generated by the small PV panel gets stored in a battery, which provides several hours of light before the lamp will need a recharge. 

Environmental Benefits and Drawbacks

An investment in high-quality solar lights can provide years of virtually carbon-free lighting for homes, offices, parks, gardens, and public infrastructure. It’s a great way for an individual or community to conserve energy and reduce disruptions posed by extreme weather and climate disasters. 

For communities that lack centralized energy infrastructure, including many rural communities around the world, solar lighting makes a big contribution to energy independence. It also contributes to public safety by illuminating walkways and streets, reducing traffic accidents, and increasing personal security.

However, solar lighting, like all solar energy systems, has environmental impacts. The batteries and electronic components will eventually become waste, and that waste has hazardous ingredients that must be properly managed in order to avoid toxic pollution. Batteries can contain lead, lithium, plastics, and sulfuric acid; PV panels contain silicon, aluminum, tin, copper, cadmium, and lead; electrical components contain plastics and metals. If not disposed of properly, these substances can pollute the air, soil, and water. 

This is a particular challenge in developing countries, where waste management is more likely to be conducted without regulation to ensure safe disposal. The absence of this process can produce e-waste that poses serious threats to the environment. Some countries require or encourage end-of-life recycling of at least some of these products.

Today, there are calls to strengthen such practices and ensure that solar projects everywhere support safe disposal and recycling of solar materials once the components have reached the end of their productive use. Of course, this is important not only for solar but traditional lighting. 

Wherever you live, it's important to research the longevity of your solar lighting products and prioritize quality. Opt for those which are likely to last, so the environmental benefits don't dwindle.