Birgunj, Madhesh, Nepal presents a reasonably good location for year-round solar energy generation, though with some notable seasonal variations that potential solar installers should understand.

Seasonal Solar Performance

The solar energy output at this Northern Sub Tropical location shows interesting patterns throughout the year. Spring emerges as the standout season, delivering an impressive 6.28kWh per day for each kilowatt of installed solar capacity. This makes it the optimal time for solar generation at this site. Summer and autumn perform similarly well, producing 4.65kWh and 4.68kWh per day per kilowatt respectively. Winter shows the lowest performance at 4.14kWh per day per kilowatt, though this reduction is relatively modest compared to many other locations at similar latitudes. For anyone installing a fixed solar panel system at Birgunj, Madhesh, the optimal tilt angle is 26 degrees facing south. This angle maximizes total year-round energy production by accounting for the sun's changing position throughout the seasons and the varying solar irradiance levels.

Environmental and Weather Challenges

Several local factors in Birgunj could potentially impact solar energy production and require careful consideration during installation:

• Monsoon season impacts: Nepal experiences heavy monsoon rains typically from June to September, which can significantly reduce solar output due to cloud cover and reduced sunlight
• Dust and air pollution: Being located near the Indian border in the Terai region, Birgunj experiences considerable dust and air pollution that can accumulate on solar panels
• High humidity levels: The subtropical climate brings high humidity, which can affect equipment performance and longevity
• Extreme weather events: The region can experience severe storms, hail, and strong winds during monsoon periods

Preventative Measures for Better Performance

To maximize solar energy production despite these challenges, several installation strategies prove effective: Regular cleaning schedules become essential, particularly during dusty periods. Installing panels with easy access for maintenance helps ensure consistent performance. Using anti-soiling coatings on panel surfaces can reduce dust accumulation and make cleaning more effective. Proper drainage systems around the installation prevent water pooling during heavy rains. Selecting equipment rated for high humidity and temperature variations ensures longer system life. Installing surge protectors and lightning protection becomes crucial given the risk of electrical storms. Choosing mounting systems designed to withstand high winds and potential hail damage provides better long-term reliability. Additionally, considering micro-inverters or power optimizers can help maintain system performance even when individual panels experience shading or soiling issues. Despite these environmental challenges, Birgunj's solar potential remains quite favorable, especially during the excellent spring season and decent performance in other seasons, making it a viable location for solar energy projects with proper planning and maintenance.

Note: The Northern Sub Tropics extend from 23.5° latitude North up to 35° latitude.

So far, we have conducted calculations to evaluate the solar photovoltaic (PV) potential in 40 locations across Nepal. This analysis provides insights into each city/location's potential for harnessing solar energy through PV installations.

Link: Solar PV potential in Nepal by location

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

Seasonal solar PV output for Latitude: 27.0159, Longitude: 84.8808 (Birgunj, Nepal), 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 26° South in Birgunj, Nepal

To maximize your solar PV system's energy output in Birgunj, Nepal (Lat/Long 27.0159, 84.8808) throughout the year, you should tilt your panels at an angle of 26° 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 Birgunj, Nepal

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 Birgunj, Nepal. As mentioned earlier, for fixed-panel solar PV installations, it is optimal to maintain a 26° South tilt angle throughout the year.

Overall Best Summer Angle	Overall Best Autumn Angle	Overall Best Winter Angle	Overall Best Spring Angle
11° South in Summer	33° South in Autumn	42° South in Winter	21° 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 Birgunj, Nepal

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 Birgunj, Nepal.

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 Birgunj, Nepal

Topographical Features of Birgunj

Birgunj sits in the southern plains of Nepal, positioned within the Terai region that forms part of the expansive Indo-Gangetic Plain. This area is characterized by remarkably flat terrain, with elevations ranging from approximately 60 to 200 meters above sea level. The landscape consists primarily of alluvial plains formed by sediment deposits from rivers flowing down from the Himalayas over thousands of years. The region experiences a gentle gradient sloping southward toward the Indian border, which lies just a few kilometers away. The terrain is predominantly agricultural, featuring vast expanses of fertile farmland interspersed with scattered settlements and transportation corridors. Small seasonal streams and irrigation channels crisscross the landscape, though these waterways typically have minimal impact on the overall flatness of the terrain.

Nearby Elevated Areas

Moving northward from Birgunj, the topography begins to change as the land approaches the Mahabharat Range, which forms the first significant hill system north of the Terai plains. These hills rise gradually, reaching elevations of 1,500 to 2,000 meters above sea level approximately 50 to 80 kilometers north of Birgunj. The transition from plains to hills occurs over a relatively short distance, creating distinct topographical zones. The Churia Hills, also known as the Siwalik Range, represent the first line of elevated terrain encountered when traveling north from Birgunj. These hills typically reach heights of 700 to 1,000 meters and are located roughly 30 to 40 kilometers from the city. The terrain in this transitional zone becomes increasingly undulating with moderate slopes and valley systems.

Optimal Areas for Large-Scale Solar Development

The extensive flat plains surrounding Birgunj present exceptional opportunities for large-scale solar photovoltaic installations. The most suitable areas lie within a 20 to 30 kilometer radius of the city, where the terrain remains consistently level and agricultural land use patterns allow for potential energy development projects. Areas to the east and west of Birgunj offer particularly favorable conditions, as these zones maintain the characteristic flatness of the Terai while being less densely populated than areas immediately surrounding the city center. The terrain in these directions continues the same alluvial plain formation, providing stable ground conditions suitable for mounting large solar arrays. The agricultural lands between Birgunj and the smaller settlements of Pokhariya and Jitpur present ideal topographical conditions for solar development. These areas benefit from minimal elevation changes, good accessibility via existing road networks, and sufficient distance from major population centers to minimize land use conflicts.

Terrain Considerations for Solar Installation

The predominantly clay and silt-based soils of the region provide stable foundations for solar mounting systems, though proper engineering assessment would be necessary to account for seasonal moisture variations. The flat terrain eliminates concerns about shading from topographical features and allows for optimal panel orientation without the need for extensive site preparation or grading. Seasonal flooding represents the primary topographical challenge in some low-lying areas near water courses. However, large portions of the plains around Birgunj sit at sufficient elevation to avoid regular inundation while maintaining the advantageous flat profile ideal for solar installations. The absence of significant rock outcroppings or steep slopes throughout the region means that site preparation costs would typically remain minimal compared to more mountainous areas. The consistent elevation and gentle terrain gradients also facilitate efficient construction logistics and ongoing maintenance access for large-scale solar facilities.

Nepal solar PV Stats as a country

Nepal ranks 89th in the world for cumulative solar PV capacity, with 93 total MW's of solar PV installed. This means that 0.10% of Nepal's total energy as a country comes from solar PV (that's 43rd in the world). Each year Nepal is generating 3 Watts from solar PV per capita (Nepal ranks 86th in the world for solar PV Watts generated per capita). [source]

Are there incentives for businesses to install solar in Nepal?

Yes, there are incentives for businesses wanting to install solar energy in Nepal. The Government of Nepal has implemented a number of policies and programs to promote the use of renewable energy sources such as solar power. These include tax exemptions, subsidies, and other financial incentives for businesses that install solar systems. Additionally, the government has established a Renewable Energy Fund which provides grants to support research and development activities related to renewable energy technologies.

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