A small PV system brings light to the rural community of Setal, Guatemala.
In the 1990s, while working as a corporate security consultant, my father, Guillermo Diaz Salazar, decided to get back to his agricultural roots and restore degraded land in Alta Verapaz, an area in north-central Guatemala. He convinced a group of investors to transform 200 acres of eroded bush space into a pine tree farm that would provide jobs for local people and produce sustainably forested timber.
As part of the plan, the seven Mayan families who had lived on the land for generations were employed at the tree farm and given ownership of a 5-acre parcel to farm and live on. Collectively, the land and their huts—including one for my father—form the village of Setal. For his role, my father visits the community once every two months to manage the tree farm and help the people with their ongoing efforts to develop community infrastructure.
Developing eroded rainforest into a tree farm has been a slow process, but in 15 years, the village has come a long way. Not only have the workers successfully cultivated the land and planted hundreds of trees, but the community pooled its resources to build a schoolhouse for the growing number of children in the area. Though rudimentary in form, the new school—a one-room hut with a tin roof and stick walls—was a tremendous step for the community.
With 70% illiteracy in rural areas, education offers the best hope for Guatemala to develop politically, socially, and economically. At the root of the problem is the language barrier that isolates many rural communities from the rest of the country and the world. Although Spanish is Guatemala’s official language and is widely used for trading goods, it is not universally spoken outside of major cities. More than two dozen languages are spoken throughout the country—the Mayan dialect of Keqchi, for example, is the traditional language in Setal. Until a few years ago, only one of the men in the community spoke Spanish. With a curriculum taught in Spanish, the Setal school aims to increase fluency in the area.
The school opened in January 2006 with a program tailored for first- through sixth-grade students. But before long, it became clear that the adults in the village were also interested in learning to read and write in Spanish. Since they worked in the fields during the day, their classes needed to happen at night. That posed a problem because there was no electricity at the schoolhouse, and lanterns and candles could not effectively light the classroom.
A temporary solution came in the form of an old and battered gasoline generator that powered a few lights, allowing adults to attend night classes where they learned how to write their names for the first time. Unfortunately, the cost of purchasing and transporting gasoline to Setal was prohibitive, and the generator proved unreliable, breaking down two times in only a few months.
I was born and raised in El Salvador, but my father and much of my family now live in Guatemala. Though I have lived in North America for 19 years and raise my family in Ohio, I still feel a strong connection to the region. After learning about the school from my father, my husband and I decided to get involved, and made plans to take our two young daughters to the village on our next trip to Guatemala.
Our girls spent months collecting books and supplies for the school, while my father and I raised funds to help with other community projects, including the village’s first bathrooms with gravity-fed plumbing. We scheduled our visit for the end of the school’s first year, so we could congratulate the students on their achievements. The girls were amazed to see how such small contributions—colored pencils, notebooks, pens, and the like—brought so much joy to the people of Setal. While we’d done more than most, it wasn’t enough for me. I was determined to help further, and I knew exactly who to turn to.
My childhood friend Ralf Seip is a longtime solar energy enthusiast. In the 1980s, Ralf bought his first PV modules to power a cassette player so we could listen to music at the beach. Now, a utility-intertied PV system at his home offsets almost half of his family’s annual electricity use. (See “Experimenting with Solar Hot Air Collectors” in HP72 and “Growing with the Sun,” in HP107.)
As soon as I told Ralf about the school, he suggested an alternative to Setal’s gasoline generator: a battery-based solar-electric system that would provide clean, reliable electricity. The idea quickly took shape, and we got to work immediately, soliciting funding and donations for the project.
Since I had no experience in PV design or installation, I followed Ralf’s lead. He started by estimating the schoolhouse’s electrical loads, figuring that the 16- by 20-foot classroom would be well-illuminated by four compact fluorescent lights (CFLs). A fifth light outside the schoolhouse door would provide added security and safety. The four interior lights would be used as necessary (approximately 4 hours nightly) while the outside light would remain lit throughout the night (approximately 12 hours).
To maximize energy availability and minimize system costs, Ralf chose to bypass the use of an inverter and use 12-volt DC compact fluorescent lights. He determined that the five 7-watt CFLs would consume 196 watt-hours of energy each day and would require about 16 amp-hours from a 12 VDC battery bank. To prolong battery life and to have some remaining capacity to supply lighting during cloudy periods, Ralf did not want the batteries discharged by more than 15%, and sized the bank accordingly. A 102 Ah, 12 VDC battery bank met this criteria. A 90 W, 12 VDC PV array is capable of replenishing this capacity on a typical day with 5 peak sun-hours, as Ralf conservatively estimated based on 80% module efficiency, 95% charge controller efficiency, and 80% battery efficiency.
In the far corners of the Guatemalan jungle, there are no local hardware stores or overnight delivery services for last-minute needs—preparation is key. To work out some of the kinks in advance, Ralf preassembled and tested the system at his home in Indianapolis. Since he would be unable to make the trip to Guatemala, he walked me through the design and installation to ensure that I could reassemble the system. Once in Setal, I would need to lead my father and the community members through the installation process. Preassembling the system ensured that we had everything we needed and everything was in working order. Knowing that this would be my first PV installation, Ralf cut the wires to size so I could focus on the mechanical installation when in Setal.
Early in the design phase, Ralf and I decided that we would save on shipping costs and transport the components by packing them in my luggage. Carrying the components also ensured that everything arrived in one piece and on time to Guatemala City, where I met my father. Miraculously, everything we needed—the charge controller mounted on a wood support; seven 12.6 W, 11- by 17-inch PV modules; 12 VDC CFLs; wiring; and assorted small hardware—fit in two suitcases.
Upon my arrival in Guatemala City, my father and I had one day to collect the remaining hardware before departing for the village. In addition to the supplies for the mounting frame, we locally acquired two Deka sealed lead-acid batteries. We loaded up the supplies and hit the road.
Transporting the system components and supplies to Setal wasn’t nearly as smooth or comfortable as the first leg of my trip. Potholed dirt roads made the nine-hour drive through the countryside and jungle feel like an eternity. But the incessant bumps were nothing compared to the two-hour trek to the village. After driving all day, we arrived at the end of the dirt road, where we left the car and found men from the village waiting for us. They came to help us carry the supplies and system components for the remaining two-hour muddy trek to the village. Since hauling heavy loads on their backs is a way of life for the locals, the supplies and equipment posed no real challenge to them. They practically ran up the hills while we struggled with our small packs.
With a small crew from Setal, it took us three days to execute Ralf’s plans for installing the PV system. The schoolhouse roof offered a perfect place to mount the array, but we had to build a custom rack to face the modules south on the sloping roof. This turned out to be the most difficult part of the project, as some of the materials and tools were not on site as expected. We ended up removing wallboards from my father’s hut to build the module rack’s base.
Using rough hardwood boards left from the school’s bathroom building, the Setal men built a battery box that could be locked for safety and security. The charge controller was installed next to the battery box in the schoolhouse. Running the pre-cut wires and attaching the lights to the crossbars on the ceiling of the schoolhouse rounded out the installation. Having the village men help with the installation and module wiring gave me a chance to teach them about basic electricity, safety, and system maintenance. Having no experience with electricity, the whole crew looked at this as a new beginning and a great learning tool.
Simple and reliable components that could be easily maintained over time were selected for this system. We chose a charge controller with a low-voltage disconnect and wired all of the loads through it. This means that energy will stop flowing to the loads when the controller detects a low voltage on the batteries—11.4 V in the case of the Morningstar PS-30. Power will be restored only after the controller detects a battery voltage that exceeds 12.6 V. This feature helps extend the life of the batteries and prevents abuse from overdischarging. We also simplified system maintenance by using sealed lead-acid batteries that do not require watering.
My father and I trained community members to read and interpret battery health and system status using the Morningstar controller’s display. This enables them to manage loads (i.e., turn off lights or use fewer lights) and activities based on the available solar resource and battery state of charge.
With grid electricity in the region still a decade or two away, PV arrays are valuable and sought-after commodities. After a solar-electric system was stolen from a nearby clinic, the community decided to take extra measures to protect its system. Men from the participating villages now take turns spending the night at the schoolhouse to watch over the system. This, along with the outside light, a locked battery box, and a securely attached PV array, should deter bandits from burglarizing the system.
After one final check of the polarity, voltages, and charging current, the moment came to switch on the system. It was standing room only in the schoolhouse, when Cristina—a shy 15-year-old—flipped the switch and filled the schoolroom with light.
The system has been operational since that ceremonious night in December 2007, and according to my father’s reports, it is serving the community well. The school now has 26 day students: 14 boys and 12 girls, ranging from 4 to 16 years old. Twenty-two adults—12 men and 10 women—gather three times per week for night classes. Interest has been so great that adults and children are coming from as far as three miles away to attend the Setal school. And, on weekend evenings, the community takes full advantage of the lights by using the schoolhouse as a prayer hall and a gathering place for celebrations and meetings.
Ralf intentionally oversized the charge controller, which can handle 30 A of solar charging current, to allow for future system expansion by adding more PV modules, batteries, or both. Choosing 12 VDC as the system voltage gives great flexibility for module additions, since these are readily available to ship and can easily be paralleled to increase production. This allows us to accommodate future donations more easily, as modules can be bought online one at a time.
Ralf, my father, and I remain committed to helping the community of Setal become a regional hub for education, community activities, and basic health care, all while empowering the people with increased control over their future. We’ve had great donations from the RE community, including the controller from Morningstar, the CFLs from Backwoods Solar, and module shipping covered by DM Solar. The additional funds needed came from friends and family. Plans are already underway to expand the capacity of the system to support a TV/VCR system for educational programming. We are also looking for support to add two additional solar-electric systems to the community: one to power lights for six huts and another to support refrigeration and lights for a small health clinic set to open next year.
Cecilia Diaz-Beneke is a chemical engineer with a specialty in polymers. She is currently taking a break from her career to raise her daughters, Maia and Karina.
Ralf Seip is an engineer working in the medical device field. He is in the process of relocating his family, along with his home’s solar-electric system, from Indianapolis to New York for job-related purposes.
Backwoods Solar • www.backwoodssolar.com • 12 VDC CFLs
Dmsolar • www.dmsolar.com • PV modules
East Penn Manufacturing • www.eastpenn-deka.com • Batteries
Morningstar • www.morningstarcorp.com • Charge controller