The winter season and accompanying snow will reduce the production of solar panels—there’s no denying that. While that shouldn’t be surprising, there are still plenty of misconceptions around solar panel operation and snow. Let’s dive into some of these solar + snow myths, shall we?
SNOW AND SOLAR PANELS
A snowy winter day is not ideal for three out of the four major factors that affect solar panel performance:
Length of day—————————————————-shortest of the year
Angle of sunlight relative to the panel————–least direct sunshine of the year
Sunlight intensity——————————-diminished by cloud and snow cover
Temperature————-panel production actually improves in colder temperatures
All these factors result in a significant reduction of energy during the winter months. A rough rule of thumb is that wintertime production is about one-third of summertime production while spring and fall production is about two-thirds that of summertime production.
That doesn’t mean solar panels aren’t a good investment in regions with snowy winters. Check out these map projections from Stanford’s DeepSolar project.
A greater number of solar installations in the southwestern United States clearly correlates with a greater average solar radiation level, but the wintry northeast also shows robust growth, thanks in part to generous state and local renewable energy incentives. New York, Massachusetts, and New Jersey all rank in the top 10 for installed solar capacity. Solar panel savings are often more dependent on electricity prices than the weather.
Looking globally, Germany led the world in solar capacity from 2005 to 2013 even though it receives comparable levels of sunlight as Alaska.
Winter weather shouldn’t stand in the way of going solar!
SOLAR PANELS IN WINTER Q&A
SINCE IT’S SO CLOUDY IN THE WINTER, WILL MY SOLAR PANELS PRODUCE ANY ELECTRICITY AT ALL?
Yes, your solar system will produce power during cloudy weather. As mentioned above, lower temperatures are better for the material properties of the panels.
How much power is generated depends on the degree of cloudiness, but even under solid cloudy skies, a solar array will produce between 10 — 30 percent of its power rating.
WHAT ABOUT WHEN IT SNOWS?
Solar panels can still generate electricity through a thin layer of snow though several inches or more will render the panel inoperable. That being said, snow’s reflective properties can potentially help boost panel production if the array itself is not covered. It goes without saying, but heavy snow that completely blocks the solar cells from receiving sunlight will prevent generation until either the snow melts or is brushed off.
There are strategies to deal with snow, such as mounting panels at steeper angles so that any accumulated snow simply falls off, but generally, grid-tied solar panels are mounted flush with the roof slope, which is typically not very steep. Eventually, snow will still naturally melt and slide, and power generation will begin again as parts of the panel are exposed.
The good news is that for grid-tied, net-metered systems, the goal is generally to produce the maximum amount of energy on an annual basis. Typically, homeowners with residential solar panels will produce more energy in the summer months and accumulate additional net-metering credits from their utility that can be stockpiled to offset for the lower solar production of the winter months.
HOW DO I REMOVE SNOW FROM MY SYSTEM IN THE EVENT OF A BIG SNOW DUMP?
Given the inherent safety concern of climbing on one’s roof in the winter, it’s almost always better to wait for the sun and gravity to take care of any snowy panels. It’s also a way to get a free cleaning. Snow bonds with dirt and debris and washes it clear of the modules as it melts.
Manually removing snow will likely take a lot more energy, risk, and expense than the value of the energy gained. A lot of snow will mean a longer stretch of no production, which may tempt owners to try to remove the snow. Other than a soft roof rake or broom, there are no safe ways to remove snow from an array, nor is such an action recommended. Stay warm and wait for a sunny day to melt the snow away.
These same considerations apply for flat roofs.
About the only time it’s worth trying to remove snow is for off-grid systems where daily energy production is critical. When the only energy you have is the energy you make, getting any snow off the panels will make a big difference. If you have a ground-mounted solar power system that is more accessible, it is generally fine to just brush off any snow as needed.
One additional concern for heavy snow to note is the added weight load of any snow accumulation on a home’s roof. A lot of snow means more weight on the array and the roof. Fortunately, this additional weight is taken into account when designing the array structure and evaluating the roof’s ability to handle the array in the first place.
WHAT EFFECT DOES NIGHT AND DAY TEMPERATURE VARIANCE HAVE ON A SOLAR SYSTEM / SOLAR PANELS?
Large night and day temperature shifts, especially in winter, creates stress on the solar system as components contract and expand. Solar panels have proven their ability to handle these stresses for many decades in the field.
Advances in solar panel design and construction are leading to some of the most resilient systems yet for temperature stresses. Sunpower’s Maxeon solar cells, for instance, use thicker panel to panel connections with built-in strain relief to virtually eliminate the threat of breakage from temperature swings.
The electronic components in optimizers and micro-inverters (components of some solar systems) are much more vulnerable to temperature swings than solar panels due to their myriad of tiny soldered connections. It is for this reason that we at IPS stay away from these devices except when dealing with very shady conditions where the decreased component reliability is worth the added production.
To talk with one of our friendly solar experts about solar for your home, contact us.