Three Approaches to Solar Energy for Puerto Rico: Scales of Solar Intervention in Disaster Resilient Energy Strategy

by Garrett Burnham

The current state of Puerto Rico’s energy grid leaves its citizens vulnerable to the potentially disastrous effects of another Hurricane Maria. Given the remote, mountainous nature of most of the island’s interior and the diminishing ability of its central power provider, PREPA, to maintain the existing grid, alternative energy solutions, like solar, have become a common response at the community and municipality levels. During my time in Puerto Rico, I was deeply interested in several solar energy strategies that we saw or heard about, but I felt that there was a lack of strategy around deciding which system was best for a given region. What works in the towns and remote areas of Utuado, for example, may not be the best solution for Mayaguez. How can the appropriate solar energy solution be determined for communities with diverse needs and characteristics? In the course of this paper, I will describe three solar energy solutions, and the underpinnings for a method of analyzing a community’s needs and selecting the right solution. This is intended as the beginning of a conversation and not the end all be all of this topic. My hope is that this report can become a jumping off point for such discussions. Before I can begin laying out this framework, I must first explain how I got to this topic and question in the first place.

At the beginning of my trip to Puerto Rico, I was not focused on solar energy, but on healthcare design. What I discovered though, was that many of the challenges facing Puerto Rico’s healthcare system were deeply interlinked with another interest of mine, solar energy. After hearing from public health expert Jonathan Castillo talk about the dangers posed to the island because of its fragile energy system, I knew that my experience in the solar industry could be more valuable than my more limited experience with healthcare design. Moreover, I began to notice myself being drawn into conversations about energy more than the healthcare side of things.

In particular, a conversation with our supporting faculty member from the University of Puerto Rico (UPR) Mayaguez, Cecilio Ortiz García pointed out that a community's needs and desires have to be taken into consideration when developing a new energy proposal. Designers and policy developers cannot simply mandate a particular power solution but must be sensitive to the dynamics of a community and how people collaborate with one another. Moreover, my time as a solar PV (photovoltaic) system designer for All Energy Solar in St. Paul, MN taught me that there are nuances to installing solar arrays that I felt were being overlooked by many of the policy discussions that we heard. For instance, little attention was given to the conditions of buildings and homes, many of which were still covered in the blue FEMA tarps put up after Maria. This information is important to consider because for roof mounted solar arrays to be viable, the underlying building structure must be suitable for carrying the additional system’s weight. These were the aspects of my experience both before and during my trip that helped to shape my research question around suitable solar solutions. With that understanding, I will begin to lay out the three solar strategies of interest here.

Distributed, Rooftop Microgrids

The first strategy, a distributed, rooftop microgrid, is arguably one of the most versatile and flexible. This strategy relies on the ability to install many small solar panel installations on individual homes and businesses that can then be connected together and balanced to create a grid-tied, islandable microgrid network. This will likely require a bit of explanation for anyone unfamiliar with the terminology around these types of systems, so I will take this opportunity to briefly go over it. For starters, a microgrid is loosely defined as an energy generating system that can be connected to a larger energy grid (grid-tied) but also has the ability to operate independently of that grid (islandable)[i]. What this means for communities with microgrids is that they can disconnect from a malfunctioning grid after a disaster and operate on their own energy production.

One of the key challenges of this type of distributed system, however, is that the production is coming from multiple small arrays that are all producing energy at different levels. This is where the idea of balancing comes into play. During our discussions with Felipe Patarroyo Montenegro, UPRM Ph.D. student in electrical engineering, and Marcel Castro-Sitiriche, UPRM electrical engineering professor with the Sustainable Energy Research Center, we learned that in order for a grid to be functional, the loads and supply must be balanced with one another. This becomes an increasingly complicated task however when there is a distributed network of linked solar arrays all producing different amounts of energy at different times of the day. The SERC Microgrid Lab is researching ways of handling this issue using computer models and physical electrical equipment to simulate the energy demand and supply of a microgrid system[ii].

One of the other challenges to a distributed rooftop system, as stated before, is that it is often hard to tell what condition a communities buildings are in and if they are suitable for installing solar on them. If a building’s roof is rotting, or its structural members are too small, it won’t be able to support the additional weight of a new solar array. Furthermore, there are the considerations of available space on the roof and solar exposure. It is one thing to look at a satellite image of a city and count rooftops, but an entirely different level of challenge to go into that community and inspect the actual roof structure, and take exposure readings. There are methods for doing all of these things, and they are quite effective. We can send technicians into the field to gather readings on solar exposure, identify potential shading concerns, and even structural issues ahead of time. This all costs a great deal of money and time, however, as the process must be carried out in person and for each potential building. The issue then becomes, how can we hasten this process without losing effectiveness, and how can we determine if a community is suitable for this level of in-depth study?

That being said, some examples of this type of microgrid already exist in Puerto Rico and have proven successful. The community of El Coquí for instance and the municipality of Adjuntas (through the organization Casa Pueblo) have both managed to engage their communities to learn more about solar energy and how to install their own systems. Casa Pueblo had installed numerous solar systems in Adjuntas prior to Maria, and as a result, were among the few who still had power after Maria. This allowed the organization to continue its important operations such as its local radio station which broadcast important information to the area[iii]. In El Coquí, local students were taught the basics of solar energy and 3 electrical systems and aided in the installation of panels on local homes and buildings. This had the dual benefit of educating the students on the importance of understanding energy use and supply as well as bringing power back to the area[iv].

Centralized Ground Mounted Microgrid

A centralized Ground Mounted Microgrid system operates much like the distributed system, but as the name suggests, the panels are located in one large array rather than many distributed arrays. The benefit to this arrangement is that the panels are all tied into the same inverter setup, and all roughly generating on the same level that is much easier to balance out than the distributed method. One of the drawbacks, however, is that they take up land that may or may not be available in all areas of the island. A densely populated city like San Juan, for example, would struggle to find the open land necessary to build an array that would meet at least part of its energy needs. Furthermore, it can be challenging to build such arrays on sloped topography making the interior of the island a challenge as well despite its lower land development. While I did not observe any microgrids of this sort in Puerto Rico, there use in community solar projects throughout the US suggests that they are a viable option.

 

Community Center/ Solar Oasis Approach

The final approach for solar energy systems explored here is the creation of a centralized hub of energy with a limited range. These hubs typically are installed on Community centers (town halls, churches, etc.) or can be stand-alone objects that are portable and delivered directly to the sites they are needed at. They have the benefit of being small, relatively easy to install, and flexible to meet different community needs. Community center systems, in particular, benefit from being located at popular urban destinations familiar to citizens. This often makes them key locations for disseminating and receiving information, medical care, food, supplies, and other important disaster relief.

One example of the many community center installations that we came across was the work of Marvel Architects. Marvel and their partner organization Resilient Power Puerto Rico have successfully installed solar panels on several community centers throughout the island. Some of the centers included four buildings in the Caño Martin Peña District of San Juan, the Atmar Educational Center in Maunabo, and the Daguao Community Center in Naguabo[v]. The installations were paid for through monetary donations as well as material donations from the various communities.

The other half of this strategy is the potential for a portable solar oasis system that can be dropped into communities after disasters to meet immediate energy needs. These types of solutions have the potential to reach even the most remote areas of the island quickly if properly designed and planned for ahead of time. One of the most developed proposals for a mobile solar oasis is that of the San Juan based company HiveCube. The company’s design for a solar oasis is based on a refurbished shipping container that would support a medium-sized solar array and a variety of functions ranging from medical services to emergency dispatch communications center. The benefits to using a shipping container being that there is a readily available stock of defunct containers available for purchase, and they can be easily loaded onto flatbed trucks and hauled to sites all over the island. The solar panels themselves would be designed to pack down into the container for shipping and a crew would help local communities learn the procedures for setting up and taking down the array. This last component has proven to be a valuable (if underdeveloped) benefit as being able to quickly disassemble the array would allow communities to store the vulnerable solar panels inside the container during subsequent storms. The containers would also be outfitted with their own battery storage to allow for the continued use of excess energy after the sun has gone down[vi].

One of the major drawbacks to both of these styles of centralized systems is that they are limited in their capacities to only a few kilowatts. This means that they must focus their energy production on only the most vital community needs, and those needs can only be met at the site of generation for the most part. Furthermore, with the use of shipping containers, in particular, there are still unaddressed challenges of finding suitable sites for them within communities. Some of the denser urban locations may find it difficult to allocate a centrally located vacant lot to place the container on. Another concern that should be raised is that of transportation itself. Post Maria, many of the islands critical roads and bridges were either heavily damaged, destroyed, or obstructed by debris. The prospect of getting a large truck through some of these areas would have been impossible for many months after the initial disaster when people needed emergency power most. This brings me to my closing section on how we best determine which of these solutions works for which communities.

Implementation and Designation of Suitable Solutions

Overall, I have identified several criteria we can use to assess a communities needs and which type of solar installation they are able to benefit from most.

  • Community Size

  • Community density

  • Relative topography of Area served

  • The average integrity of building structures

  • Solar Access (how much sun is available in the area)

  • Accessibility from urban centers (e.g. San Juan)

  • Presence of open land

  • Presence of suitable community centers

  • Purchasing power of community

  • Average age of community population

By examining communities and municipalities based on these criteria, we can effectively build a picture of their ability to host one or more of the above solar energy solutions and determine the right solution for them. For example, an interior community with a low density, mountainous topography, and low access to urban areas may be more suitable for a centralized ground-mounted array if the land is available. Otherwise, a centrally located community center with solar may be the best option. Given that the homes are likely spread out over greater distances, a distributed network of arrays would be increasingly unmanageable and harder to maintain. Another example might be a small city with few residents, higher density, but no suitable land for developing a ground-mounted array. In this case, a community center and or distributed array may work if the community's homes and businesses are properly up to specifications needed to carry the panels safely. Here, the value of performing a field survey of homes and businesses may be justifiable, but the issue of cost may be prohibitive. For this reason, it would be imperative to form partnerships between local community organizations and solar panel installation companies early on to better facilitate cost-effective surveys. This could potentially take the form of a community-driven survey task force trained by professionals to go out and identify prime properties for solar installation ahead of time. By leveraging community activism and volunteers, smaller cities and towns could more effectively plan their distributed energy systems.

 

Relation of Goals to Healthcare

In order to bring my work full circle, I wanted to briefly discuss the implications of improved energy resilience on healthcare. During our conversations with both Jonathan and the leaders of Casa Pueblo in Adjuntas, one recurring story that has been well documented is that people with chronic conditions were left without power to support their medical needs. In particular, patients relying on insulin were unable to adequately refrigerate their supplies without power, and people needing dialysis were unable to find clinics with the power to perform the procedure. Many of the solutions we saw included mini solar-powered refrigerators and community centers hosting medical refrigeration space, as well as dialysis machines. This would not have been possible without the presence of solar panels at these locations.

Another example of energy’s implications on public health stems from the current solutions being used in disaster-stricken areas. In the aftermath of Maria, thousands of gasoline and diesel generators were utilized around the clock to create the majority of the islands power needs for those disconnected from the grid. The resultant air pollution (among other hazards) dramatically impacted people's health leading to complications for those with conditions like asthma as well as the young and elderly. Some families even resorted to bringing generators inside their homes to avoid theft leading to some dying from carbon monoxide poisoning[vii]. With the implementation of solar energy systems in more communities, fewer people will need to rely on diesel generators, and hopefully avoid the associated health impacts.

The efficacy of solar energy for increasing the resilience of Puerto Rico’s grid is apparent, but the appropriate methods for achieving that future are hard to comprehend and untangle. This paper alone only scratches the surface of one corner of that broader conversation. In order to have progress on this front, we must also consider the complex nature of the existing energy grid and the governance surrounding it. The thicket that is PREPA’s current predicament is enough to fill several journals worth of essays, so for the time being, I have chosen to limit this exploration to the more utilitarian concerns of categorization and implementation. Looking forward, it will be important to continue to uncover more criteria for assessing community needs and suitability and even more varieties of solar energy systems. What I have provided here is merely a start, and I hope to see it grow. The people of Puerto Rico, all of them, deserve an energy grid that they can depend on. No matter where they live.


[i] US Department of Energy, Berkeley Lab, https://building-microgrid.lbl.gov/microgrid-definitions

[ii] Montenegro, Filipe. Lecture. January 11, 2019, UPR Mayaguez Sustainable Energy Research Center

[iii] González, Alexi Massol, Lecture, Casa Pueblo. January 12, 2019, http://casapueblo.org/

[iv] Byer, Elizabeth, Community Solar for Sustainability in Puerto Rico. Social Justice New Network, April 10, 2018,

http://sjnnchicago.medill.northwestern.edu/blog/2018/04/10/community-solar-sustainability-puerto-rico/

[v] Marvel Architects, Resilient Power Puerto Rico https://marvelarchitects.com/work/resilient-power-puerto-rico/100

[vi] Hive Cube Presentation, January 16, 2019 atInstitute of Puerto Rican Culture, Vieques PR

[vii] Jonathan Castillo Polanco. Lecture. January 7, 2019 INESI Workshop