Contrary to popular belief, solar panels do generate electricity in the fall and winter months. In fact, solar panels produce energy even during cloudy weather, just at a lower rate. Because solar energy production relies on sunlight and we tend to have more cloudy weather in Oregon during the winter, solar system output does decline somewhat.
Although the days are shorter in the fall and winter months, the temperatures are also lower. Solar panel efficiency actually increases in the winter months compared to the dog days of summer. When temperatures are too high, solar panels become less efficient in converting sunlight into an electrical current.
When will my solar panels produce the most energy?
This question depends on where your home is located. If you live in Northern Alaska, your system will barely produce any electricity in the winter because the days are so short. By comparison, we have far better winter solar system output in Oregon.
Let’s compare the energy production between three identical systems installed in Portland, Salem, and Medford, Oregon. All three solar systems will produce less electricity in November, December, and January and more power during June, July, and August. In the Willamette Valley and on the Oregon coast, we tend to have cloudy weather in the winter months and lots of sun in the summer. In the Rogue Valley, including Ashland and Medford, Oregon, the winter months are less cloudy than in the Portland area.
How does location impact solar system output?
Realtors have a saying, “Location, location, location!” Just like the real estate market, location is also critical in the solar energy industry. The output of your solar system varies by the local climate, rooftop shading, angle of the roof, and the orientation of your home.
Rooftop Shading
The angle of the sun is lower in the sky in the winter than in the summer. Often, the impacts of shading from other buildings greater in the winter months than in the summer months. For example, if you have a tall house just south of your home, it might shade your roof some in the winter months but not the summer.
The same thing doesn’t always apply to trees because deciduous trees lose their leaves in the winter. Conversely, evergreen trees can have a bigger impact on winter shading because they have their needles year-round.
Location in Oregon
Let’s examine those three identical six-kilowatt solar energy systems again. The solar panels in Portland, Oregon, where the winters are relatively cloudy, will generate about 6,800-kilowatt hours of electricity annually. An identical solar panel system in Salem, Oregon, will actually produce a tiny bit more power at 7,000-kilowatt-hours of estimated production. Meanwhile, a solar energy system in Medford, Oregon, will create an estimated 8,200-kilowatt hours of solar electricity. On average, Medford gets about half as much rain a year compared to Portland. Therefore they have less cloudy weather.
Roof Pitch
The angle of your roof is called the pitch. Your solar system will generate the most power when the sun hits the roof at a 90-degree angle.
Because the sun’s angle is lower in the sky in the winter, the output of your solar system will vary depending on the pitch of your roof. If you have a steep roof, your solar panels will generate more energy in the winter and less in the summer, as a result. Alternately, if you have a gently-sloped roof, your solar system will create more power n the summer and less in the winter as a result.
Some utility-scale solar farms use tracking devices on the solar panels, so they follow the sun. Solar tracking devices are rarely used in residential solar projects because the panels are usually installed on the roof. Also, tracking devices add considerably to the cost of a solar energy system. In most cases, the Smart Solar Energy team recommends a fixed solar system.
The Smart Solar Energy team is skilled in designing solar PV systems that maximize energy output. To learn more about going solar, contact us today for a free solar audit.
Roof Orientation
Ideally, solar panels will face south to generate the most solar energy. If they face southwest or southeast, they will still produce a significant amount of energy. When solar panels are mounted facing east, they have excellent morning production, but their evening production suffers. Likewise, when solar panels face west, they produce more power in the afternoon at the expense of morning solar generation. Unfortunately, the Smart Solar Energy team does not recommend mounting panels facing north because the system will not produce much energy.
Weather Variations
The Smart Solar Energy team uses historical weather data to estimate future solar energy production. Of course, there are variations in the weather periodically. Sometimes, we experience an arid spring or an atypically wet fall. In addition, climate change is altering the climate in Oregon, encouraging more intense storms and even droughts in some areas.
Will snow decrease the output of my solar energy system in Oregon?
Many solar energy enthusiasts are concerned about the impact of snow on solar panel output. When solar modules are covered in snow, they produce little or no power. Thankfully, we get very little snow in Western Oregon, and it has a minuscule effect on overall solar energy production.
Whenever possible, the Smart Solar Energy team installs PV panels facing south and at an angle. Thus, snow slides off of the solar panels, especially when the sun emerges and starts to warm things up. Because solar panels are a dark color, the temperature increases relatively easily when the sun is out. Then, the snow begins to melt and slides off.
At Smart Solar Energy, we don’t recommend raking snow from solar panels. Raking snow can be dangerous and can damage the solar PV panels or your roof. Thus, we recommend waiting for the sun to clear the panels for you.
Do solar panels generate power at night?
No, solar modules only produce electricity when the sun is shining. After the sun sets, there is not sufficient solar radiation to generate a current. Even a full moon doesn’t produce enough light to power your solar panels. Does this mean your solar-powered home won’t have electricity at night?
Thankfully, grid-tied solar systems have power 24/7. When the sun is shining, your home will use solar electricity first. If you need more than the system is generating, your house will pull power from the utility grid. If you have surplus solar energy and no batteries, all this power will go to the grid, and you will receive credits on your Portland General Electric or Pacific Power bills.
Both utility companies have net metering programs. This means they will credit your account for surplus energy you feed to the grid. Then, when you use power at night, it will come from your solar credits. Net metering makes it possible to virtually eliminate your utility bill if your system is large enough to produce the power you consume over the course of a year. Even though your solar energy system won’t generate electricity at night, you can still use your solar credits to power your home.
Should I oversize my solar system to have more power in the winter?
At Smart Solar Energy, our team is skilled in accurately sizing a solar system to maximize the value. Even though your solar panels will likely produce less power in the winter months, your electricity use might be minimal as well if you do not use electric heating. Many Oregon households actually use more energy in the summer when they have the air conditioning cranking.
If your system is oversized, you might not be able to use all the solar credits you generate under net metering. If the solar system is undersized, you won’t be able to virtually eliminate your power bill. If the roof is too small or there are other design constraints, it might be your best option to have a slightly undersized solar system.
A Smart Solar Energy expert will determine what sized system you need based on your roof measurements, electricity bills, shading, budget, and other factors during our solar audit. If you plan home upgrades that will considerably change your future electricity use, such as installing an electric vehicle charger or converting to electric heat, please let us know.
Click here to schedule a free solar audit. This process involves sizing a solar system for your home and determining the estimated energy production and the cost. Remember that you may be eligible for a solar tax credit that reduces the net system cost by 26%.
How can I maximize my winter solar energy production?
As much as we love trees, they can decrease your solar energy output. Therefore, we do not recommend planting trees where they will eventually shade your solar panels. Keep in mind your solar system is designed to last for 25 or more years. This means that the trees you plant now could be shading your panels down the road.
The most critical time for your solar panels to be in full sun is during the middle of the day when the solar system output is greatest. A bit of early morning or late afternoon shade won’t significantly impact total system production. Unfortunately, shading between 10 am and 2 pm could dramatically impact your total system production.
Trees just to the south of your solar system can have the biggest impact on solar production. In addition, trees on the east side of the home may produce morning shade, and trees on the west side could shade your array in the afternoon.
Therefore, plant varieties of trees that will not be tall enough to shade your roof. Likewise, deciduous trees tend to have less impact because they lose their leaves in the winter months when the sun is lower in the sky. Conversely, trees on the north side of your house should have no impact on your solar generation (unless they have long branches that cover your roof).
In some cases, a minor tree trimming can significantly increase your solar system output. You can view solar monitoring data to determine the impacts of shading on your solar panels to make an informed decision. Keep in mind that shading will vary by the season and is usually the most during the late fall and early winter when the sun is lowest in the sky.
Will my solar panels produce enough power if my roof is very shaded?
Unfortunately, not all homes have good solar energy potential. In some cases, a detached garage might be a better location for your panels. If you have sufficient yard space, a ground-mounted array in a sunny place is another good option. If the roof is sunny, the Smart Solar Energy team typically recommends using the house roof first. The cost of a ground mount is usually a bit higher because it involves purchasing a more extensive racking system. The Smart Solar Energy team is dedicated to making solar cost-effective for our customers. Therefore, we make recommendations that will boost the return on investment of your solar project.
Want to learn more about installing solar panels on your house? Contact the Smart Solar Energy team today to get started!
