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Sunshine on a Cloudy Day – Why Solar Still Works in Clouds, Rain, or Shine

When it comes to generating power from the sun, there’s a misconception that home solar systems don’t work in cloudy weather. However, ask anyone who’s ever gotten sunburned when it is cloudy out, and they will tell you a different story. That’s because solar radiation, better known as Ultra Violet rays, can penetrate clouds and produce energy.

Depending on the type of cloud cover, solar panels might produce 10-25% of their rated wattage. Thanks to significant increases in panel efficiency over the last decade coupled with their declining prices has allowed homeowners to install more panels for less, reducing the weather’s gross impact in performance.

Solar panel efficiency has increased over time
Solar Panel Price Per Watt
Solar panel pricing has decreased over time

Famously gray cities such as Seattle and Portland are among the top 20 leaders in America in terms of solar capacity. Washington’s generous payback incentive and net-metering policy have helped encourage the adoption of solar, allowing homeowners to benefit from reduced electric bills and a greater confidence in their self-reliance should a power outage occur. 

Similar to cloudy days, solar panels also work in the rain. Counter intuitively, the rain can actually benefit panels, by washing away dust and dirt debris on panels, allowing them to perform better when the sun peaks back through. 

Homeowners planning for solar in a cloudy, rainy, or even seasonally snowy environment, should consult with a solar expert to size their system and design a solar array specific for their geographic location.

Basic calculations to gauge a system’s size can be made with the following formula:

Array Size (kW) = (Annual kWh usage) / (365 days/year) / (Solar Hours – 1.5/day) / (0.82 derate factor) 

How Many Sun Hours a Day Do You Get?
Zone 1      6 hours
Zone 2      5.5 hours
Zone 3      5 hours
Zone 4      4.5 hours
Zone 5      4.2 hours
Zone 6      3.5 hours

Since systems will usually yield less energy during the winter months, its safe to subtract ~1.5 solar hours to account for decreased sunlight and ensure your system will meet all your power needs.

Home solar supplier GoGreenSolar carries panels that are best suited for cloudy, rainy or even snowy conditions —  Hanwha Q Cells, NEO and LG Solar are among the top performers in adverse conditions. To figure out what solar panels and system array is best for your home call for a free consultation: 866-798-4435

Author: Harold Tan

I believe clean, renewable energy is key to the evolution of society as a whole. Solar powers our planet, why not harness it to power humanity? Let's power our homes, our work, and our vehicles with solar energy. It begins with raising awareness and encouraging those around us to go green.

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