The location of Vashon, Washington, in the United States, presents a mixed scenario for solar PV energy generation throughout the year. Situated in the Northern Temperate Zone, this area experiences significant seasonal variations in solar energy production.

Seasonal Solar Energy Production

Summer stands out as the most productive season, with an impressive 6.87 kWh per day for each kilowatt of installed solar capacity. This high output is due to longer daylight hours and more direct sunlight during the summer months. Spring follows as the second-best season, generating 5.15 kWh per day. This season offers a good balance of increasing daylight hours and moderate temperatures, making it an excellent time for solar energy production. Autumn sees a significant drop in energy output, producing 2.47 kWh per day. The decreasing daylight hours and potentially cloudy weather contribute to this reduction. Winter presents the biggest challenge, with only 1.27 kWh per day. Short days, low sun angles, and frequent cloud cover typical of the Pacific Northwest winter contribute to this low output.

Optimal Panel Installation

For fixed panel installations in Vashon, the ideal tilt angle to maximize year-round production is 39 degrees facing South. This angle helps optimize solar capture across all seasons, balancing the high summer sun with the lower winter sun angles.

Environmental and Weather Factors

Several factors can impact solar production in Vashon: 1. Cloud cover: The Pacific Northwest is known for its cloudy weather, especially in fall and winter. This can significantly reduce solar output. 2. Rain: Frequent rainfall, particularly in the cooler months, can further decrease energy production. 3. Tree shading: Vashon's lush vegetation might cast shadows on solar panels, reducing their efficiency. To mitigate these factors, consider the following preventative measures:

• Use high-efficiency panels that perform well in low-light conditions
• Implement a robust cleaning schedule to remove rain residue and debris
• Carefully plan panel placement to minimize shading from trees and structures
• Consider adding a solar tracking system to maximize sun exposure throughout the day

While Vashon's location presents challenges for year-round solar energy production, proper planning and installation can still yield significant benefits, especially during the productive summer and spring 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 Vashon

Seasonal solar PV output for Latitude: 47.4473, Longitude: -122.4599 (Vashon, 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 Vashon, United States

To maximize your solar PV system's energy output in Vashon, United States (Lat/Long 47.4473, -122.4599) 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 Vashon, 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 Vashon, 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
31° South in Summer	50° South in Autumn	61° South in Winter	40° 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 Vashon, 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 Vashon, 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 Vashon, United States

The topography around Vashon, United States, located at coordinates 47.4473°N, 122.4599°W, is characterized by its island setting in the Puget Sound region of Washington State. Vashon Island is part of an archipelago that includes Maury Island, connected by a narrow isthmus. The landscape is generally hilly and forested, with a mix of gentle slopes and steeper terrain. The island's highest point, Maury Island's Maury Hill, reaches an elevation of about 535 feet (163 meters) above sea level. The coastline is irregular, featuring numerous bays, inlets, and beaches. The interior of the island is dotted with small lakes, wetlands, and streams, creating a diverse ecosystem.

Solar PV Potential in the Region

When considering areas nearby that would be most suited to large-scale solar PV installations, it's important to note that the Puget Sound region, including Vashon Island, is not ideal for solar energy production due to its climate and latitude. The area experiences frequent cloud cover and receives less direct sunlight compared to more southern regions of the United States. However, if solar PV projects were to be pursued in the vicinity, the most suitable locations would likely be found on the mainland, east of Vashon Island. The areas around Kent, Auburn, and Tacoma offer more expansive flat terrain that could accommodate large-scale solar installations. These locations benefit from being further inland, potentially experiencing slightly less cloud cover than the immediate coastal areas. It's worth noting that any large-scale solar PV project in this region would need to carefully consider environmental impacts, land use regulations, and the region's unique ecosystem. Additionally, innovative technologies designed for diffuse light conditions might be necessary to maximize energy production in this climate.

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.