Yelm, Washington, located in the Northern Temperate Zone, presents a mixed picture for year-round solar energy generation. The location experiences significant seasonal variation in solar output, which is typical for its latitude and regional climate conditions.

Seasonal Solar Performance

Summer represents the peak solar generation period at this location, producing 6.78 kWh per day per kW of installed solar capacity. This strong summer performance makes it an excellent time for maximum energy production. Spring also offers good solar potential with 5.21 kWh per day per kW, making it the second-best season for solar generation. Autumn sees a notable decline in solar output to 2.71 kWh per day per kW, while winter presents the most challenging conditions with only 1.29 kWh per day per kW. This dramatic seasonal swing from summer to winter highlights the location's dependence on longer, sunnier days for optimal solar performance.

Optimal Panel Configuration

For maximum year-round solar production at this Yelm location, solar panels should be installed at a fixed tilt angle of 39 degrees facing south. This optimal angle is calculated by analyzing daily solar elevation angles throughout the year and weighting them according to solar irradiance potential, accounting for Earth's elliptical orbit around the sun.

Local Factors Affecting Solar Production

Several environmental and weather factors in the Yelm area can significantly impact solar energy generation:

• Frequent cloud cover and overcast conditions: The Pacific Northwest is known for its cloudy weather, particularly during autumn and winter months
• Heavy rainfall: While rain can help clean panels, persistent wet weather reduces solar irradiance
• Morning fog and mist: Common in this region, especially during cooler months
• Wildfire smoke: Increasingly common during summer months, which can significantly reduce solar output despite clear skies
• Tree coverage: The heavily forested region can create shading issues

Preventative Measures for Better Solar Performance

Several strategies can help maximize solar energy production despite these local challenges: Panel positioning should prioritize areas with maximum southern exposure and minimal tree shading. Consider professional tree trimming or removal where appropriate and legally permissible. Installing panels on the highest practical point of a roof or property can help avoid ground-level fog and maximize exposure above tree lines. Regular maintenance becomes crucial in this climate. Panels should be cleaned more frequently due to dust accumulation from dry summers and organic debris from surrounding forests. Installing panels at the optimal 39-degree angle also helps with natural rain cleaning and prevents debris accumulation. Consider investing in higher-efficiency panels or microinverters that can better capture available light during overcast conditions. These technologies can help maximize energy production even when solar irradiance is reduced by clouds or atmospheric conditions. Energy storage systems become particularly valuable at this location due to the significant seasonal variation in solar output. Battery storage can help capture excess summer production for use during the lower-production winter 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 Yelm

Seasonal solar PV output for Latitude: 46.942, Longitude: -122.606 (Yelm, 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 39° South in Yelm, United States

To maximize your solar PV system's energy output in Yelm, United States (Lat/Long 46.942, -122.606) throughout the year, you should tilt your panels at an angle of 39° 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 Yelm, 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 Yelm, United States. As mentioned earlier, for fixed-panel solar PV installations, it is optimal to maintain a 39° 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	61° South in Winter	39° 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 Yelm, 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 Yelm, 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 Yelm, United States

Topographical Features of Yelm

Yelm sits in the southern Puget Sound region of Washington State, positioned on relatively flat terrain that forms part of the Puget Sound Lowland. The immediate area around Yelm is characterized by gently rolling hills and prairie-like conditions, with elevations typically ranging from 200 to 400 feet above sea level. This low-lying landscape represents some of the most level ground in western Washington, having been shaped by ancient glacial activity that left behind fertile soils and modest topographical variations.

The terrain gradually rises toward the east as it approaches the foothills of the Cascade Range, while to the west the land remains relatively flat until reaching the more dramatic coastal topography near Olympia. The Nisqually River flows through the broader region, creating small valleys and floodplains that add subtle variation to an otherwise gentle landscape. Agricultural fields and pastureland dominate much of the surrounding area, indicating the suitability of the terrain for development and land use activities.

Optimal Areas for Large-Scale Solar Development

The expansive flat to gently sloping areas south and southeast of Yelm present the most promising opportunities for large-scale solar photovoltaic installations. These locations benefit from minimal topographical obstacles and existing agricultural use patterns that could accommodate solar development with relatively straightforward site preparation. The open prairie-like conditions in these areas provide excellent access for construction equipment and maintenance vehicles while minimizing the need for extensive grading or terrain modification.

Areas along the Yelm-Tenino corridor offer particularly suitable conditions, where the landscape remains consistently level across large contiguous parcels. The slightly elevated positions in this region also provide natural drainage advantages while maintaining the flat orientation ideal for solar panel arrays. These locations are far enough from the Nisqually River valley to avoid flood-prone areas while remaining accessible to existing transportation infrastructure.

The agricultural fields extending eastward toward the Cascade foothills also present viable options, particularly where the terrain maintains gentle southern-facing slopes. These areas combine favorable topographical conditions with sufficient distance from forested regions that might create shading concerns. The existing pattern of large agricultural parcels in these locations would facilitate the assembly of appropriately sized sites for utility-scale solar developments while maintaining compatibility with the rural character of the region.

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!

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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.