Longview, Washington, United States presents a challenging location for year-round solar energy generation, with significant seasonal variations that make it less than ideal for consistent solar power production throughout the year.

Seasonal Solar Performance

The solar energy output at this location varies dramatically across the seasons. Summer provides the strongest performance at 6.78 kWh per day per kW of installed solar capacity, making it an excellent time for solar generation. Spring also offers good production levels at 5.21 kWh per day per kW, providing another favorable period for solar energy harvesting. However, the performance drops considerably during the cooler months. Autumn sees a significant decline to 2.71 kWh per day per kW, while winter presents the most challenging conditions with only 1.29 kWh per day per kW of production. This represents nearly an 80% reduction in output compared to peak summer performance.

Optimal Installation Configuration

For maximum year-round energy production at this location, solar panels should be installed at a fixed tilt angle of 38 degrees facing south. This angle has been calculated to optimize total annual solar output by accounting for the sun's changing position throughout the year and weighting the angles based on solar irradiance data.

Environmental and Weather Challenges

Several local factors in Longview, Washington can significantly impact solar energy production and should be considered during installation planning. The Pacific Northwest climate brings frequent cloud cover and precipitation, particularly during the fall and winter months. This weather pattern directly correlates with the reduced solar output observed during these seasons. Rain, snow, and persistent overcast skies can substantially decrease the amount of sunlight reaching solar panels. The region's high humidity and frequent rainfall create conditions that promote moss and algae growth on solar panels. These organic materials can accumulate on panel surfaces, creating shadows and reducing light absorption efficiency. Additionally, the area's proximity to forests and vegetation means that pollen, leaves, and other debris can collect on panels, further impeding performance.

Preventative Measures for Enhanced Performance

Several strategies can help maximize solar energy production despite these environmental challenges:

• Install panels with adequate spacing and ventilation to prevent moisture accumulation and promote natural cleaning from rainfall
• Implement a regular cleaning and maintenance schedule, particularly during spring when pollen is heavy and after storm seasons
• Consider anti-reflective coatings and hydrophobic treatments that help panels self-clean and resist organic growth
• Ensure proper drainage around the installation area to prevent standing water that could promote moss growth
• Trim nearby vegetation regularly to minimize shading and reduce debris accumulation

The location's challenging winter conditions make it particularly important to design systems with adequate tilt to allow snow and debris to slide off naturally. Professional installation should account for local building codes regarding snow loads and wind resistance typical in the Pacific Northwest region. While Longview's solar potential is limited compared to sunnier climates, proper installation techniques and maintenance practices can help optimize the available solar resource, particularly during the productive spring and summer months.

Note: The Northern Temperate Zone extends from 35° latitude North up to 66.5° latitude.

So far, we have conducted calculations to evaluate the solar photovoltaic (PV) potential in 4253 locations across the United States. This analysis provides insights into each city/location's potential for harnessing solar energy through PV installations.

Link: Solar PV potential in the United States by location

Solar output per kW of installed solar PV by season in Longview, Washington

Seasonal solar PV output for Latitude: 46.1382, Longitude: -122.9382 (Longview, Washington, United States), based on our analysis of 8760 hourly intervals of solar and meteorological data (one whole year) retrieved for that set of coordinates/location from NASA POWER (The Prediction of Worldwide Energy Resources) API:

 

Ideally tilt fixed solar panels 38° South in Longview, Washington, United States

To maximize your solar PV system's energy output in Longview, Washington, United States (Lat/Long 46.1382, -122.9382) throughout the year, you should tilt your panels at an angle of 38° South for fixed panel installations.

As the Earth revolves around the Sun each year, the maximum angle of elevation of the Sun varies by +/- 23.45 degrees from its equinox elevation angle for a particular latitude. Finding the exact optimal angle to maximise solar PV production throughout the year can be challenging, but with careful consideration of historical solar energy and meteorological data for a certain location, it can be done precisely.

We use our own calculation, which incorporates NASA solar and meteorological data for the exact Lat/Long coordinates, to determine the ideal tilt angle of a solar panel that will yield maximum annual solar output. We calculate the optimal angle for each day of the year, taking into account its contribution to the yearly total PV potential at that specific location.

Seasonally adjusted solar panel tilt angles for Longview, Washington, United States

If you can adjust the tilt angle of your solar PV panels, please refer to the seasonal tilt angles below for optimal solar energy production in Longview, Washington, United States. As mentioned earlier, for fixed-panel solar PV installations, it is optimal to maintain a 38° South tilt angle throughout the year.

Overall Best Summer Angle	Overall Best Autumn Angle	Overall Best Winter Angle	Overall Best Spring Angle
30° South in Summer	49° South in Autumn	60° South in Winter	38° South in Spring

Our recommendations take into account more than just latitude and Earth's position in its elliptical orbit around the Sun. We also incorporate historical solar and meteorological data from NASA's Prediction of Worldwide Energy Resources (POWER) API to assign a weight to each ideal angle for each day based on its historical contribution to overall solar PV potential during a specific season.

This approach allows us to provide much more accurate recommendations than relying solely on latitude, as it considers unique weather conditions in different locations sharing the same latitude worldwide.

Calculate solar panel row spacing in Longview, Washington, United States

We've added a feature to calculate minimum solar panel row spacing by location. Enter your panel size and orientation below to get the minimum spacing in Longview, Washington, United States.

Our calculation method

1. Solar Position:
   We determine the Sun's position on the Winter solstice using the location's latitude and solar declination.
2. Shadow Projection:
   We calculate the shadow length cast by panels using trigonometry, considering panel tilt and the Sun's elevation angle.
3. Minimum Spacing:
   We add the shadow length to the horizontal space occupied by tilted panels.

This approach ensures maximum space efficiency while avoiding shading during critical times, as the Winter solstice represents the worst-case scenario for shadow length.

Topography for solar PV around Longview, Washington, United States

Topographical Features Around Longview

Longview sits in the Columbia River valley in southwestern Washington State, positioned at a relatively low elevation of approximately 20 feet above sea level. The city occupies a strategic location where the Cowlitz River meets the mighty Columbia River, creating a landscape dominated by river terraces and floodplains. This confluence has shaped the surrounding terrain into a series of gentle slopes and flat bottomlands that extend outward from the riverbanks.

The immediate area around Longview is characterized by rolling hills that rise gradually from the river valley floor. To the north and east, the terrain becomes increasingly hilly as it approaches the foothills of the Cascade Range, though these elevations remain modest within a 20-mile radius of the city. The western approaches feature similar undulating topography, with scattered ridgelines and valleys that eventually lead toward the Pacific coastal ranges.

Dense coniferous forests blanket much of the higher elevations surrounding Longview, consisting primarily of Douglas fir, western hemlock, and western red cedar. These forested areas give way to agricultural lands and pastures in the lower elevations, particularly in the river valleys where the soil is rich and well-drained. The region's topography has been significantly influenced by both ancient volcanic activity from the Cascade Range and the massive Missoula Floods that carved the Columbia River Gorge thousands of years ago.

Optimal Areas for Large-Scale Solar Development

The most promising locations for substantial solar photovoltaic installations lie in the agricultural valleys and cleared plateaus within a 30-mile radius of Longview. The Cowlitz River valley, extending northeast from the city, offers extensive flat to gently rolling terrain that has already been cleared for farming operations. These areas provide the dual advantages of minimal terrain modification requirements and existing agricultural infrastructure that could support solar development.

South of Longview, across the Columbia River in Oregon, the landscape opens into broader valleys with excellent southern exposure potential. The rolling hills in this region feature numerous south-facing slopes that would be ideal for solar panel orientation, while the agricultural nature of the land use suggests fewer environmental constraints compared to forested areas.

The plateau areas east of Longview, particularly those that have been previously logged or converted to pastureland, present another category of suitable terrain. These elevated but relatively flat areas often provide unobstructed sky access while avoiding the environmental sensitivities associated with old-growth forest areas. The existing road networks serving the timber industry in these regions would facilitate construction and maintenance access for large-scale solar facilities.

Areas to avoid for solar development include the steep-sided valleys that cut through the region, heavily forested slopes that would require extensive clearing, and locations prone to frequent fog formation near the river confluence. The most practical sites combine gentle topography, existing land clearing, good road access, and proximity to electrical transmission infrastructure that serves the region's industrial facilities.

United States solar PV Stats as a country

United States ranks 2nd in the world for cumulative solar PV capacity, with 95,209 total MW's of solar PV installed. This means that 3.40% of United States's total energy as a country comes from solar PV (that's 26th in the world). Each year United States is generating 289 Watts from solar PV per capita (United States ranks 15th in the world for solar PV Watts generated per capita). [source]

Are there incentives for businesses to install solar in United States?

Yes, there are several incentives for businesses wanting to install solar energy in the United States. These include federal tax credits, state and local rebates, net metering policies, and renewable energy certificates (RECs). Additionally, many states have enacted legislation that requires utilities to purchase a certain amount of electricity from renewable sources such as solar.

Do you have more up to date information than this on incentives towards solar PV projects in United States? Please reach out to us and help us keep this information current. Thanks!

Citation Guide

Article Details for Citation

Tell Us About Your Work

We love seeing how our research helps others! If you've cited this article in your work, we'd be delighted to hear about it. Drop us a line via our Contact Us page or on X, to share where you've used our information - we may feature a link to your work on our site. This helps create a network of valuable resources for others in the solar energy community and helps us understand how our research is contributing to the field. Plus, we occasionally highlight exceptional works that reference our research on our social media channels.

Feeling generous?

Share this with your friends!

Compare this location to others worldwide for solar PV potential

The solar PV analyses available on our website, including this one, are offered as a free service to the global community. Our aim is to provide education and aid informed decision-making regarding solar PV installations.

However, please note that these analyses are general guidance and may not meet specific project requirements. For in-depth, tailored forecasts and analysis crucial for feasibility studies or when pursuing maximum ROI from your solar projects, feel free to contact us; we offer comprehensive consulting services expressly for this purpose.

Helping you assess viability of solar PV for your site

Calculate Your Optimal Solar Panel Tilt Angle: A Comprehensive Guide

Enhance your solar panel's performance with our in-depth guide. Determine the best tilt angle using hard data, debunk common misunderstandings, and gain insight into how your specific location affects solar energy production.