What time of year do solar panels output energy?

February 08, 2017

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Lighthouse Solar

Understanding how your solar system performs throughout the year is essential for owners and prospective solar users. In the northeastern United States, we observe considerable variations in daily solar energy output over the year.

Solar Power Generation in Summer vs. Winter

Solar panels typically generate 40-60% less energy during December and January compared to July and August. This results in significantly reduced solar power generation in winter compared to summer.

Annual Energy Output of Solar Panels

From data collected through our Lightgauge monitoring systems, we can track energy output variations year-round. Dividing the year at the Vernal and Autumnal Equinoxes (March 21st and September 21st) provides a clear picture of this variation.

• Approximately 65% of the annual energy output occurs from March 21st to September 21st.
• The remaining 35% is generated between September 21st and March 21st.

Additionally, examining the two-month periods around the Summer and Winter Solstices (June 21st and December 21st) highlights the seasonal changes: energy production in June and July contrasts sharply with December and January.

Why Do Solar Panels Produce Less Energy During Winter?

Several factors contribute to this seasonal variation:

• Shorter days - Winter days being much shorter than summer days means less operational time for the solar system daily, resulting in reduced energy production.
• Sun angle - Besides shorter days, the sun's angle is lower in winter, causing sunlight to hit the panels less directly, thus lowering power output.
• Atmospheric conditions - Winter is characterized by stormy weather and cloud cover, with snow potentially covering panels, further hindering energy conversion until cleared.

Impact on Energy Bills During Winter

How does this seasonal variation affect your utility bills? High electricity bills during winter due to lower solar production and increased usage might seem inevitable. However, net metering offers a solution.

While designing solar systems, we factor in total annual electricity usage. For customers with sufficient roof or ground space, systems are designed to overproduce in spring, summer, and early fall, banking kilowatt-hours with the utility to offset reduced production in winter. This mitigates the impact of northeastern winters through optimal system design and net metering.

With competitive prices and timely delivery, BEBEST sincerely hopes to be your supplier and partner.

Do Solar Panels Work On Cloudy Days?

The assumption that solar systems can't function on cloudy days is false. They do produce energy, albeit at 10-25% of their standard output on clear days. The exact percentage varies depending on the cloudiness. Here again, net metering plays a role, storing excess energy from sunny days to be used on cloudy ones.

What We Advise

For customers who get their systems interconnected outside of March and April, we recommend using the utility's "Anniversary Date Change" process. This ensures optimal use of net-metered energy credits throughout the year. For more information on optimizing your anniversary date, contact Lighthouse Solar and speak to our Technical Sales Engineers.

Call Lighthouse Solar at (845) 251-2012 or contact us online to learn more about the seasonality of solar production!

Switching to solar energy is a smart investment for homes or businesses, regardless of the season. Utilizing solar energy can significantly reduce energy costs, though it's crucial to understand the seasonal differences in solar panel output.

Solar Panel Output in Winter vs. Summer

During winter, solar panels produce about 50% less energy compared to summer, due to reduced sunlight exposure. While they still function in winter, energy output soars during summer with longer sunlight hours.

Factors Affecting Solar Energy Production

Ideally, solar panels would consistently produce the same energy daily, simplifying power management. However, numerous factors influencing energy production are season-dependent.

• Geographic location - The amount of daylight varies with geographic location and seasons. Shorter winter days reduce solar energy production, necessitating more reliance on public utilities.
• Time of day - Besides daylight saving changes, winter days have later sunrises and earlier sunsets, further limiting solar energy production and increasing dependence on public utilities.
• Season - Longer summer days enable more solar power generation, which can be stored for use during shorter winter days.
• Landscape - Geographical features like mountains can cause some areas to lose sunlight sooner, reducing solar energy production earlier in the day.
• Atmospheric conditions - Winter often brings cloudy or rainy weather, decreasing sunlight exposure and solar energy production. This doesn't lead to complete power outages but increases reliance on public grid power.

What to Expect From Solar Production in Winter Months

Does this mean solar panels are useless in winter? Absolutely not. Solar panels actually run more efficiently in cooler conditions, facilitating smoother electricity flow and extending panel lifespan.

Countries like China, Germany, and Japan are leaders in solar energy, despite their colder climates. Similarly, California residents benefit from net-metering laws, accumulating energy credits during productive summer months to offset higher winter usage.

For more information about solar power during winter, reach out to SunPower® by Quality Home Services at (800) 496-3074 or fill out our online contact form!

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