Saturday, January 11, 2014

Designing PV for snowy climate

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Are Solar Panels Usable in Snowy Climates?

By Erin Cassidy, Accuweather.com Staff Writer
January 11, 2014; 10:00 AM
With a new year beginning, installing solar panels is a great way to fulfill environmentally-friendly resolutions.
However, for those living in wintry climates, snow accumulation may pose a problem.
Joshua Pearce, associate professor at Michigan Tech University (MTU), said, "If snow is completely covering the panel, you are obviously only going to get the amount of energy out of the panel from the amount of light that is able to pass through the snow."
"Even having a relatively small amount of snow on top of a given panel can radically reduce the amount of energy output for your entire system," he said.
Due to these issues, research is currently being conducted whether solar technology is useful in wintry climates.
Solar panels at the top of a mountain. (Credit: Flickr/SteFou!)
The projected losses could affect energy costs for all homeowners using solar power, but only significantly for ones that rely entirely on solar power and are not connected to the traditional electrical grid.
For the vast majority of homes and businesses that still remain "on-the-grid," the financial impacts are minimal but the energy losses still pose questions to enhance optimal usage.
Research being conducted in Michigan, Colorado and Washington by MTU and the engineering firm DNV GL is designed to test the energy output for solar panels with varying levels of snow coverage and other factors such as "racking" (the accumulation of snow at the bottom of a panel if the snow can't slide off naturally) and the angle the panels are tilted.
When the study is completed, Pearce is confident that, "Everyone, both [solar panel] designers, people that are funding systems and everyday homeowners [should] have the ability to look at your weather data for your area and predict, with very good assurance, what your snow losses or snow gains would be."
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The research is also examining the positive effects of a snowy climate on solar panels.
"When snow is on the ground and the panels are clean, the snowy surface basically acts as a mirror and you can get higher output," Pearce said. "In many cases, you end up with a small boost because of the reflection off the snow."
Pearce describes several methods they have used to increase the efficiency of panels with snow accumulations.
Solar panels are a cost-efficient form of alternative energy, with an overwhelming percentage of new systems being installed in tangent with the traditional electrical grid.
As long as a structure is connected to the power grid, electricity will not be interrupted when snow accumulation makes solar energy unattainable.
With continued research and installations, solar power remains a viable option for Americans hoping to utilize reusable energy.

Tips for Solar Power Users in Snowy Climates

Bounce a tennis ball off snow-covered panels.

Homeowners who have rooftop solar panels installed can surprisingly increase the energy output by bouncing a tennis ball off the snow-covered panels. The small divots created by the tennis ball help begin the snow shed process and allow sunlight to reach the modules and begin converting energy.

Install solar panels at the largest angle possible.

A higher angle lessens the accumulation of snow on top of the panel. "Everyone that is in a very snowy place, like in northern Michigan, should be aggressive in your tilting angle. So if you have a decision to make between something like 30 degrees or 40 degrees, it's better to go 40 degrees," Pearce said.

Don't set up panels in a way that allows snow to gather at the bottom.

Installing panels in a way that allows the snow to fall freely from the array greatly reduces the impact of snow. When snow slides off the panel at an angle and gathers at the bottom of the module, the losses can significant. "In those cases, when you have a very low tilt angle and a dam [of snow], you can lose all of the solar energy associated with the winter," Pearce said.

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