Viseu, Portugal, located at 40.6642° N latitude and -7.9072° E longitude, offers a moderate potential for solar energy generation throughout the year. This location in the Northern Temperate Zone experiences significant seasonal variations in solar output, which impacts the overall efficiency of photovoltaic (PV) systems.

Seasonal Solar Performance

The solar energy production in Viseu varies considerably across the four seasons:

• Summer: 8.02 kWh/day per kW installed
• Spring: 5.90 kWh/day per kW installed
• Autumn: 4.00 kWh/day per kW installed
• Winter: 2.24 kWh/day per kW installed

Summer stands out as the most productive season, with nearly four times the daily output of winter. Spring and autumn serve as transitional periods, offering moderate solar generation potential.

Optimal Panel Positioning

For fixed panel installations in Viseu, the ideal tilt angle to maximize year-round solar production is 35 degrees facing south. This angle takes into account the location's latitude and seasonal variations in sun position, ensuring optimal exposure throughout the year.

Environmental Considerations

While Viseu's climate is generally favorable for solar energy production, there are some factors that could potentially impact system performance:

1. Fog and mist: Viseu occasionally experiences foggy conditions, particularly in autumn and winter mornings. This can temporarily reduce solar panel efficiency. To mitigate this, consider installing panels at a slightly steeper angle to allow water droplets to run off more easily.

2. Dust and pollen: The region's natural vegetation and agricultural activities may lead to dust and pollen accumulation on panels. Regular cleaning and maintenance can help maintain optimal performance.

3. Shading from nearby trees or buildings: Conduct a thorough site assessment to ensure panels are placed in areas with minimal shading throughout the year. If necessary, consider tree trimming or adjusting panel placement to maximize sun exposure.

By addressing these factors during installation and maintenance, solar energy systems in Viseu can achieve higher efficiency and more consistent output throughout the year.

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 179 locations across Portugal. This analysis provides insights into each city/location's potential for harnessing solar energy through PV installations.

Link: Solar PV potential in Portugal by location

Solar output per kW of installed solar PV by season in Viseu

Seasonal solar PV output for Latitude: 40.6642, Longitude: -7.9072 (Viseu, Portugal), 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 35° South in Viseu, Portugal

To maximize your solar PV system's energy output in Viseu, Portugal (Lat/Long 40.6642, -7.9072) throughout the year, you should tilt your panels at an angle of 35° 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 Viseu, Portugal

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 Viseu, Portugal. As mentioned earlier, for fixed-panel solar PV installations, it is optimal to maintain a 35° South tilt angle throughout the year.

Overall Best Summer Angle	Overall Best Autumn Angle	Overall Best Winter Angle	Overall Best Spring Angle
25° South in Summer	45° South in Autumn	56° South in Winter	33° 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 Viseu, Portugal

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 Viseu, Portugal.

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 Viseu, Portugal

The topography around Viseu, Portugal, is characterized by a diverse landscape that combines rolling hills, plateaus, and river valleys. Situated in the central region of the country, Viseu is nestled within the Dão-Lafões subregion, which is known for its picturesque terrain. The city itself sits on a plateau at an elevation of approximately 450 meters above sea level. As you move outward from the city center, the landscape becomes more varied. To the east and northeast, the terrain gradually rises towards the Serra da Estrela mountain range, the highest in mainland Portugal. This transition creates a series of undulating hills and small valleys, with elevations increasing as you approach the mountains. To the west and southwest of Viseu, the land generally slopes downward towards the coastal regions. This area is marked by gentler hills and broader valleys, with several rivers carving their way through the landscape. The Dão River and its tributaries play a significant role in shaping the local topography, creating fertile valleys and occasional steep-sided gorges.

Suitable Areas for Large-Scale Solar PV

When considering areas near Viseu for large-scale solar photovoltaic (PV) installations, several factors come into play, including terrain, sun exposure, and land availability. Based on the topography of the region, some areas stand out as potentially more suitable for solar PV projects: The plateaus and gently sloping hills to the west and southwest of Viseu offer promising locations for solar farms. These areas generally have good sun exposure throughout the day and relatively flat terrain, which simplifies installation and reduces construction costs. The lower elevations in this direction also tend to have less cloud cover compared to the mountainous regions to the east. Some of the broader river valleys in the region, particularly those of the Dão River and its major tributaries, could also provide suitable sites for solar PV installations. These valleys often feature expansive flat or gently sloping areas that could accommodate large arrays of solar panels. However, care must be taken to avoid prime agricultural land and areas prone to flooding. The elevated areas to the east of Viseu, as the land rises towards the Serra da Estrela, may offer some good locations for solar farms. While the terrain becomes more challenging, these higher elevation sites can benefit from excellent sun exposure and potentially cooler temperatures, which can improve the efficiency of solar panels. It's important to note that while these areas may be topographically suitable, other factors such as grid connectivity, local regulations, and environmental considerations would need to be carefully evaluated before establishing any large-scale solar PV projects. Additionally, detailed site surveys would be necessary to determine the most optimal locations within these broader areas.

Portugal solar PV Stats as a country

Portugal ranks 32nd in the world for cumulative solar PV capacity, with 1,801 total MW's of solar PV installed. This means that 3.40% of Portugal's total energy as a country comes from solar PV (that's 23rd in the world). Each year Portugal is generating 174 Watts from solar PV per capita (Portugal ranks 29th in the world for solar PV Watts generated per capita). [source]

Are there incentives for businesses to install solar in Portugal?

Yes, there are several incentives for businesses wanting to install solar energy in Portugal. The Portuguese government offers a range of financial incentives and tax breaks for businesses that invest in renewable energy sources such as solar power. These include grants, loans, and tax credits. Additionally, the government has set up a feed-in tariff system which guarantees a fixed price for electricity generated from renewable sources such as solar power. This helps to make investing in solar energy more attractive to businesses.

Do you have more up to date information than this on incentives towards solar PV projects in Portugal? 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.