It is a fact that solar lights need solar energy for their operation; however, whether they require perfect sunlight or just daylight is a question asked by potential solar energy consumers. Understanding the working principle of solar lights can give a comprehensive understanding of how exactly they function. Solar panels get their electricity from photons that are released from the daylight rather than from the sun itself.
Do solar lights always need direct sunlight to operate?
Direct sunlight definitely provides the best conditions for the performance of the solar lights. It is always preferable to install the solar lights at a location where the panels can receive direct sunlight throughout the day and a shadow-free area is always preferred for solar light installation. India is climatically very diverse and has as much as around 300 sunny days per year and also, there are many non-sunny days.
Do solar lights work on days with no sunlight and how?
Cloudy weather can definitely affect the charging of the solar lights as the clouds do not permit as much sunlight through. There will be a drop in the longevity of illumination at night during overcast conditions. Nevertheless, rainy and cloudy days are not completely dark since the clouds do not completely block sunlight. The amount of solar radiation may vary depending on the density of clouds and the energy generation can be remarkably reduced during non-sunny days. However, solar panels continue to work even on a cloudy day and are capable of generating electricity with whatever sunlight is available.
Solar panels are known to run at a higher temperature than their surrounding temperature. Efficiency of solar panels tends to reduce as the temperature rises due to the temperature derating factor; therefore, during summer season, the performance of panels can be slightly affected. The weather is mostly cloudy during winter season too and contrary to popular belief, solar panels give out their performance during winters as the panel temperature can be the closest to the optimal temperature.
The power generation efficiency of panels also depends on the type of solar panels used. Monocrystalline panels seem to perform better during cloudy and winter days and MPPT charge controllers can produce almost twice energy than PWM controllers on a cloudy day. Modern solar street light operate using lithium-ion or LiFePO4 batteries of 3.7 or 3.2 volt both of which charge faster and the panels do not have to generate a lot of current to charge the batteries. The batteries continue to charge during non-sunny days even though at a slower rate. Using high luminous LED can also help in better illumination during monsoon nights. If the panels and the battery used are not of good quality, the performance of the solar lights can be adversely affected on a cloudy day.
Do solar lights work in extreme weather conditions?
Solar lights are designed to work in all types of weather conditions such as winter, summer, rainy, snowy or cloudy. Solar lights are observed to be giving their best performance during winter conditions because of the derating factor explained above. Solar lights have IP65 waterproofing to withstand regular snow and rain. However, there are chances of damage during high-speed wind and heavy snowfall days.
It is crucial to avoid shadows and to strategically position the solar panels so that the solar lights can offer their best even on less-than-perfect sunlight days. A fully charged solar light can run up to 15 hours and solar street lights with motion sensor and dimming features are energy efficient which can help the lights to carry on illuminating even during overcast weather. The energy saving capacity of most of the solar street lights used today is excellent which assists the solar lights to keep working for at least 2 to 3 nights.
Solar street lights are expected to light up throughout the year, especially if they are installed at a public space such as streets, highways, building perimeters, parks, etc. While they are being used in residential areas or any private spaces to ensure security and safety to the residents, usage of solar street lights on public roads helps drivers to see roadside obstacles, other vehicles and pedestrians. Solar street lights also ensure smooth operation of commercial activities at night.
All in one as well as integrated solar street lights come with energy saving options such as motion sensors and timer-based dimming features. Solar street lights that are anticipated to offer night-long illumination usually have LEDs and solar panels with higher wattage. The batteries used in these lights have more energy storing capacity and can charge faster. This stored energy helps the lights to continue to operate even during foggy or cloudy days.