Does Solar Lighting Work with Cloudy Skies?
There’s been several power outages and fires across the nation because of record-high heatwaves, and many people are switching to the best solar lighting on the market to circumnavigate the problems of faulty electrical infrastructure. However, with cloudy, ashen skies there’s been concerns about solar lighting receiving enough photovoltaic energy in order to remain on in times of need and emergency. Greenshine New Energy is here to provide what you need out of solar powered lights in order to effectively draw enough energy from the sun, even under dark skies, to provide power all night long.
Does Solar Lighting Work in Cloudy Skies? Yes, and Here’s What You Need to Look For
A solar lighting system definitely works even in very cloudy, ashen skies. Here are a few quality signifiers that your investment needs to have in order to draw enough power from the sun to keep the solar light batteries charged long-term.
Highly Efficiency, Resilient, Quality Panels
Here are three things you need to look for on your panels to make sure they are powerful enough for dark skies.
Solar panels for lighting pull in about 25% of their regular power under extremely cloudy skies, so it’s important to choose the right kind of panels that will perform even under the worst conditions to receive direct sunlight. A lot of panels use different technologies, but there are some tried-and-true kinds to stick to and specific design attributes to watch out for. You’ll want to pick a solar panel with an efficiency rating of 15-20%. The efficiency rating tells you how much power the solar panel gathers from all of the solar energy that strikes it. 15-20% might seem low, but the truth is that’s high in comparison to other technologies like thin film, which are best suited for residential solar power since they tend to take a much wider surface area than other solar forms.
It’s important to pick high-efficiency panels because they must be lightweight enough to sustain wind load. A common max load is about 140 MPH wind gusts, but the larger the panel, the more difficult it may be to hold up on top of a pole. A combination of small panel size and high efficiency works best. Monocrystalline silicon solar panels provide both high efficiency and compact size so weight and wind load aren’t problems.
It’s also important to choose a panel with a low temperature coefficient. The temperature coefficient is a design factor of a solar panel that informs you of how much a solar panel’s efficiency can drop due to high levels of heat striking the panel.
The TC states that for every degree above 25 degrees Celsius, the efficiency of the panel drops by whatever the coefficient is. So if you purchase a panel with a TC of -0.5% / C, the panel loses .5% of efficiency for every degree above 25 degrees. Anything less than .5% / C is a poor-quality panel. Keep this in mind if the project is in an arid climate where high heat is a constant.
Believe it or not, the wrong kind of glass for your solar lighting investment can severely hamper the light transmittance for your panels, and the last thing you’ll want for solar panels under cloudy skies is bad light transmittance. The best commercially-available glass for panels is tempered glass manufactured with low iron oxide to ensure high light transmittance.
Plus, an anti-reflective coating for the glass protecting the panel is best as well since you don’t want to reflect any light back from solar lighting panels under cloudy skies. Cheaper glass can end up trapping in moisture or getting cloudy, further reducing the panels’ efficiency.
In short, buy good glass. It’ll make sure you get as much power from sunlight as possible.
Proper System Sizing
A properly-sized solar light is key to ensuring proper function, and here are two main reasons why.
5 Days of Autonomy
It’s important to check with your manufacturer about the days of autonomy provided with each solar light. A minimum of autonomy is 5 days, which means if the solar panels receive no light whatsoever, the batteries can provide 5 days of power. The solar light batteries must be substantial enough in order to deliver this power. Sometimes it’s even a strong idea to double up on batteries in order to extend autonomy, but a strong rule of thumb is no less than 5 days. Greenshine’s solar lighting is designed for cloudy skies by providing at least 5 days of autonomy.
Using the Winter Solstice
Naturally, we know that not every day will be bright and sunny, so qualified lighting engineers set a baseline day to measure sun hours for new lighting projects. The best day to set a baseline with is the winter solstice, which is the darkest day of the year. Using the sun hour measurement from that day, each solar light can be properly sized with the right wattage panel and sufficient components to help keep the light fixtures on all night, even under cloudy skies.