Tag Archives: Solar farm

Designing panda solar power plants with Energy3D

Fig. 1: Panda power in Energy3D
Fig. 2: Panda power in Energy3D
A Panda-shaped photovoltaic (PV) solar power plant in Datong, China recently came online and quickly went viral in the news. While solar power plants in cute shapes are not a new thing (I blogged about the Mickey Mouse-shaped solar farm in Orlando, FL about six weeks ago), this one drew a lot of attentions because the company that built it, Panda Green Energy Group, is reportedly planning to build 100 more such plants around the world to advertise for renewable energy. According to the company's website, the idea of building Panda-shaped solar power plants originated from Ada Li, a student from Oregon Episcopal School. Li proposed her idea at the COP21 Conference in Paris.

The construction of the 100 MW Datong Panda Solar Power Plant began on November 20, 2016. It is expected to generate 3.2 billion KWh in a life span of 25 years. The plant consists of two types of solar panels of different colors: black monocrystalline solar panels and white thin-film solar panels. The two types form the characteristic shape and pattern of a giant panda, the national treasure of China and the logo of the World Wildlife Fund. Considering the number of people who complain about solar power plants being eyesores in their neighborhoods, these attempts by the Panda and Micky Mouse solar farms and their future cousins may provide examples to mitigate these negative perceptions.

Fig. 3: A close-up view of Panda power.
Fig. 4: A close-up view of Panda power.
One of our summer interns, Maya Haigis, who is a student from the University of Rochester, spent a couple of hours to create an Energy3D model of the Datong Panda Solar Power Plant after I shared the news with her today. The power plant is so new that Google Maps currently show only a picture of it under construction. So Maya went ahead to draw the power plant based on an artist's imagination taken from the news. Her design ended up using about 34,000 solar panels. To make it look like a real giant panda with its trademark black and white fur, I had to quickly add a light gray color option for solar panels in Energy3D. Maya's work came out to be amazingly realistic (Figures 1 and 2). This is even more remarkable considering that Maya had no prior experience with Energy3D.

Panda Green Energy said in the press release that they designed the power plant also for the purpose of engaging youth to join the renewable energy revolution. They are planning to reach out to schools for student site visits. There is also a plan to make the power plant a tourist attraction. I am not sure people would pay to go there to see it. But with Energy3D, we can imagine the experience by taking a virtual tour with the 3D model (Figures 3 and 4). The engineers among us can run Energy3D simulations to analyze its performance and investigate whether such an effort makes scientific sense.

So what about inviting children all over the world to "paint" the brownfields that have scarred our planet with this kind of good-looking solar power plants using Energy3D as a "solar brush?" Welcome to our Solarize Your World Initiative!

Energy3D turns the globe into a powerful engineering lab for everyone

Fig. 1: Dots represent regions supported in Energy3D.
Many of the readers of my blog may not know Energy3D is, in fact, also a Google Maps application. Energy3D allows users to import a satellite image of a site through the Google Maps API as the "ground image" in its 3D coordinate system, on top of which users can draw 3D structures such as buildings or power plants. Built-in simulation engines can then be used to test and analyze these structures without having to switch to another tool and leave the scene (something known as "concurrent design" in the CAD industry). These engines use large geographical and weather datasets for the site as inputs for simulations to accurately take environmental factors such as air temperature and solar radiation into account. As the climate is probably the single most important factor that drives the energy usage in buildings where we live and work, it is important to use weather data from a typical meteorological year (TMY) in a simulation. If no weather data is available for the site, Energy3D will automatically select the nearest location from a network of nearly 400 supported worldwide regions (Figure 1) when you import the satellite image from Google Maps. The following table lists the numbers of regions in 75 countries that are currently supported in Energy3D. The United States is covered by a network of 164 nodes. So if you are in the United States, you will have a better chance to find a location that may represent the climate of your area.

Afghanistan 1 Algeria 6 Argentina 3
Australia 5 Austria 1 Belarus 1
Belgium 1 Belize 1 Brazil 5
Brunei 1 Canada 10 Chile 12
China 31 Colombia 2 Costa Rica 1
Cyprus 2 Czech 1 Denmark 1
Egypt 1 Finland 1 France 8
Germany 12 Greece 2 Guatemala 1
Hungary 1 Iceland 1 India 4
Indonesia 1 Iran 3 Iraq 1
Ireland 1 Israel 1 Italy 4
Japan 6 Jerusalem 1 Jordan 1
Kenya 1 Kuwait 1 Lebanon 1
Madagascar 1 Malaysia 2 Mexico 3
Morocco 3 Nepal 1 Netherlands 1
New Zealand 2 Norway 1 Pakistan 2
Panama 1 Peru 1 Philippines 1
Poland 7 Portugal 2 Qatar 1
Republic of China 1 Romania 1 Russia 3
Saudi Arabia 2 Serbia 2 Singapore 1
South Africa 5 South Korea 2 South Pole 1
Spain 8 Sri Lanka 1 Sweden 1
Switzerland 3 Tanzania 2 Thailand 1
Turkey 3 UAE 1 Ukraine 1
United Kingdom 5 United States 164 Vietnam 1


Fig. 2: Solar sites in Fitchburg, MA.
Energy3D's capability of turning Google Maps into a gigantic virtual engineering lab has tremendous potential in STEM education and energy revolution. It allows students to pick and choose sites for designing renewable energy and energy efficiency solutions that are most relevant to their lives, such as their home and school buildings (Figure 2). It gives students an authentic tool that supports them to scientifically investigate all sorts of possibilities to design a more sustainable world and effectively communicate their ideas to the public. And, most importantly, with Energy3D being a free tool that anyone can use at zero cost, this can happen at the global scale to engage every student in the world to act now and make a difference!

This global vision is not new. Back in 1995, the National Science Foundation funded my colleagues Boris Berenfeld, Bob Tinker, and Dan Barstow, who were at TERC at that time, a grant to develop a curriculum that they touted as the Globe Lab. The Global Lab Curriculum meant to provide an interdisciplinary, one-year course at the secondary level that supports science standards and school reform through intercultural, scientifically meaningful, and collaborative student investigations in environmental studies. Students were given the opportunity to experience all aspects of genuine scientific research: problem identification, background study, project design, collaboration, data analysis, and communication.

Fig. 3: Solar power plants around the world.
More than 20 years later, technology has advanced so much that we now have many more resources and tools to rethink about this idea. With Google Maps and weather data for countless regions in the world, Energy3D is poised to become a true example of Globe Lab for science and engineering. The integration of the software and our Solarize Your World Curriculum with the current, unstoppable waves of renewable energy innovation and movement worldwide will create numerous exciting possibilities for youth to become truly involved and engaged in shaping their world and their future (Figure 3). While we undertake this grand challenge, it is utterly important to keep in mind that renewable energy does not just stand for some kind of green ideology related only to potential tax hikes -- it also represents trillions of dollars worth of business opportunities and investment in the coming decades committed by almost all governments on the planet to revamp the world's energy infrastructure to provide cleaner air and healthier environment for their citizens. Given this level of global significance, our work will only become more essential and the implications will only become more profound.

As we are mourning the loss of Bob Tinker, one of the architects of the Global Lab Curriculum, carrying on this line of work will be the best way to remember his visions, honor his contributions, and celebrate his life.

Accelerating solar farm design in Energy3D with a new model of solar panel racks

Fig. 1: A solar farm of 5,672 solar panels on 8/16 in Boston
The solar simulation in Energy3D is based on discretizing a solar panel, a reflector, a solar water heater, a window, or any other surface into many small cells (mesh), calculating the solar radiation to the centers of the cells, and then summing the results up to obtain the total energy output. For example, a photovoltaic solar panel can be divided into 6x10 cells (this is also because many residential versions of solar panels are actually designed to have 6x10 solar cells). The simulation runs speedily when we have only a few dozen solar panels such is in the case of rooftop solar systems.

Fig. 2: Simulation of 5,672 solar panels on 8/16 in Boston
Unlike rooftop solar systems, large-scale solar farms typically involve thousands of solar panels (mega utility-scale solar farms may have hundreds of thousands of solar panels). If we use the same discretization method for each panel, the simulation would run very slowly (e.g., the speed drops to 1% when the number of solar panels are 100 times more). This slowdown basically makes Energy3D impractical to use by those who cannot afford to wait such as students in the classroom who need to get the results quickly.

Fig. 3: The result of the accelerated model
Fig. 4: The result of the original model
Luckily, solar panel arrays are often installed on parallel long racks in many solar farms (Figure 1). For such solar panel arrays, a lot of calculations could be spared without compromising the overall accuracy of the simulation too much. This allows us to develop a more efficient model of numeric simulation to do solar radiation calculation and even explore methods that use non-uniform meshes to better account for areas that are more likely to be shaded, such as the lower parts of the solar panel arrays. By implementing this new model, we have succeeded in speeding up the calculation dramatically. For example, the daily solar simulation of a solar farm consisting of more than 5,000 solar panels took about a second on my Surface Book computer (Figure 2 -- in this scene I deliberately added a couple of trees so that you can see the result of shading). With the previous model I would probably have to wait for hours to see the result and the graphics card of my computer would take a very deep breath to render more than 5,000 dynamic textures. This is a huge improvement.

Figures 3 and 4 show a comparison of the simulation results between the new and old models. Quantitatively, the total output of the new model is 93.63 kWh for the selected day of June 22 in Boston, compared with 93.25 kWh from the original model. Qualitatively, the color shading patterns that represent the distribution of solar radiation in the two cases are also similar.

The new rack model supports everything about solar panels. It has a smart user interface that allows the user to draw racks of any size and in any direction -- it automatically trims off any extra length so that you will never see a partial solar panel on a rack. When tracking systems are used with long, linear racks, there is only one way to do it -- horizontal single-axis tracker (HSAT). The new model can handle HSAT with the same degree of speed-up. For other trackers such as the vertical single-axis tracker (VSAT) or the altazimuth dual-axis trackers (AADAT), the speed-up will not be as significant, however, as the inter-rack shading is more dynamically complex and each rack must be treated independently.

Designing solar farms and solar canopies with Energy3D

Fig. 1: Single rack
Many solar facilities use racking systems to hold and move arrays of solar panels. Support of racks is now available in our Energy3D software. This new feature allows users to design many different kinds of solar farm, solar park, and solar canopy, ranging from small scale (a few dozen) to large scale (a few thousand).

Fig. 2: Multiple racks
Mini solar stations often use a single rack to hold an array of solar panels (Figure 1). This may be the best option when we cannot install solar panels on the building's roof. You probably have seen this kind of setup at some nature centers where the buildings are often shadowed by surrounding trees.

If you have more space, you probably can install multiple racks (Figure 2), especially when you are considering using altazimuth dual-axis solar trackers to drive them. This configuration is also seen in some large photovoltaic power stations.

Fig. 3: Rack arrays
Larger solar farms typically use arrays of long racks (Figure 3). Each rack can be driven by a horizontal single-axis tracker. Using taller racks usually requires larger inter-rack spacing, which may be an advantage as it allows maintenance trucks to drive through. In a recent experiment, SunPower experimented with how to grow crops or raise animals in the inter-rack space with their Oasis 3.0 system. So arrays of taller racks may be desirable if you want to combine green energy with green agriculture.

Fig. 4: Solar canopy above a parking lot
If you raise the height of a rack, it becomes a so-called solar canopy that provides shading for human activities like the green canopies of trees do. The most common type of solar canopy converts parking lots into power stations and provides shelters from the sun for cars in the summer (Figure 4).

Designing solar canopies for schools' parking lots may be a great engineering project for students to undertake. This is being integrated into our Solarize Your School Project. In fact, Figure 4  shows a real project in Natick High School in Massachusetts. The hypothetical design has more than 1,500 solar panels (each of them has the size of 0.99 x 1.96 m) and costs over a million dollars.