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Yes, your solar panels are still producing electricity, even on cloudy days

Francisco CastroApril 3, 20193230

With Spring already in full swing and the days getting longer and sunnier, it means your home solar energy system is getting maximum exposure to the sun’s rays and therefore, you’re reaping the highest electricityy output.

But from time to time, dark clouds appear on the horizon, often for an entire day or several. 

One of the myths about solar power is that your solar panels don’t produce any electricity on cloudy days.

While this is partly true --there must be sun in order for photovoltaic cells to convert sunlight into electricity -- it doesn’t mean you’re not generating power.

“This claim is false. Solar panels can still can produce 10–25% of their typical output on a cloudy day. Obviously, this amount is much less than during periods of direct sunlight, but it is not nothing,” notes Jack Richardson of Clean Technica, the number one cleantech-focused website in the U.S. and the world.

“We may assume that solar panels thrive in hot, sunny weather, but too much heat can actually reduce solar panel output 10–25%,” he cautions.

And adds that is why a solar power system might be more effective in San Francisco than in much sunnier and hotter Las Vegas, for instance.

“Mono crystalline and polycrystalline panels do produce some electricity but in cloudy or overcast conditions their performance drops right off. In really hot conditions, their performance also degrades slightly with increase in temperature,” wrote Mike Percival, a freelance electronics engineer in Quora.

In fact, Seattle and Portland, Oregon - two of the cloudiest cities in the country -are leaders in solar power, according to environmentamerica.com.

Remember that just because it’s cloudy, doesn’t mean total absence of sun. Sun rays still make their way through rain and clouds. 

It’s the same reason why you might get sunburned when you go to the beach on an overcast day.

“Yes.. electricity production will be there, but performance of solar panel will be reduced as compared to normal clear shiny day. Electricity production through solar panels is directly dependent upon the amount of solar energy falling over it. Therefore, in cloudy weather, solar radiation available to solar panel would be less.. making reduced electricity production,” wrote Rani Poonam, a student from the Indian Institute of Technology, Kharagpur pursuing a PhD in Food Process Engineering, in a response on Quora.

Also, keep in mind that you’re home solar energy system is still connected to the utility grid. At maximum output days, it feeds any surplus electricity to the electric company. When your own domestic energy production drops, your solar system may be drawing power from the grid. So you never run out of power.

“Edge of a cloud” effect

Experts also point to another phenomenon linking solar panels and cloudy days, the so-called “edge of a cloud” effect.

This happens when the sun passes over the outer edge of a cloud, magnifying the sunlight. The intense light causes your solar panels to boost power output temporarily, which can help balance out losses from full cloud cover. 

A reputable solar panel installer is aware of this and should select solar equipment capable of withstanding these temporary boosts in capacity, without danger. 

Scientific advances

The reduced electricity output on solar panels during cloudy conditions may soon be a thing of the past.
Iflscience.com reports that researchers from the University of British Columbia, Canada have constructed bacteria-powered solar cells that work efficiently in both dim and bright light.

The Canadian team used E. coli genetically engineered to produce lycopene, the molecule that gives tomatoes their orange/red tint, which is also great at harvesting sunlight. 

“In a report on the scientific journal Small, the team of scientists coated the E.coli in a mineral that can be used as a semiconductor. They then applied the bacteria/mineral mixture to a glass surface. Like that, they constructed their biogenic solar cell. Tests showed a current density of 0.686 milliamps per square centimeter, almost double the previous record for these type of cells,” Iflscience explained..

“These hybrid materials that we are developing can be manufactured economically and sustainably, and, with sufficient optimization, could perform at comparable efficiencies as conventional solar cells,” wrote in a statement project leader Professor Vikramaditya Yadav.

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