Farming the Sun

Beginner

Inside this Article

The author (far left) instructing on module shading and other PV basics.
The author (far left) instructing on module shading and other PV basics.
One of the PV-powered cabins.
One of the PV-powered cabins.
The solar food dehydrator drying coffee, cocoa beans, and herbs.
The solar food dehydrator drying coffee, cocoa beans, and herbs.
SEI instructor Carol Weis (left) and students wiring components
SEI instructor Carol Weis (left) and students wire the controller, inverter, and disconnect boxes.
The finished structure with the modules on top.
The finished structure, which houses the battery and balance of system components, with the modules on top.
One of the hazards of traveling in the rain forest.
One of the hazards of traveling in the rain forest.
Mounting the PV modules.
Mounting the PV modules.
The outdoor classroom at the farm.
The outdoor classroom at the farm.
One of the PV-powered bathrooms.
One of the PV-powered bathrooms.
Students wire the modules.
Students wire the modules.
A superefficient LED lamp in one of the bathrooms.
A superefficient LED lamp in one of the bathrooms.
The power center, with each component labeled in Spanish and English.
The power center, with each component labeled in Spanish and English.
The truck is free—time to go home.
The truck is free—time to go home.
The author (far left) instructing on module shading and other PV basics.
One of the PV-powered cabins.
The solar food dehydrator drying coffee, cocoa beans, and herbs.
SEI instructor Carol Weis (left) and students wiring components
The finished structure with the modules on top.
One of the hazards of traveling in the rain forest.
Mounting the PV modules.
The outdoor classroom at the farm.
One of the PV-powered bathrooms.
Students wire the modules.
A superefficient LED lamp in one of the bathrooms.
The power center, with each component labeled in Spanish and English.
The truck is free—time to go home.

Just south of the equator on the Ecuadorian Pacific Coast, Rio Muchacho Organic Farm stands in the once-dense rain forest as a model of community development and sustainability. Owners Nicola Mears (an organic horticulturist from New Zealand) and Ecuadorian native Dario Proaño took over the 27-acre farm almost 20 years ago with the goal of helping the land recover from decades of burning, clear-cutting, mono-cropping, and chemical applications.

When Nicola and Dario first started growing food on the land, the region was practically a desert. The tropical rain forest had been so brutally deforested for cattle farming that barely any plant life remained. Nearly two decades later, Nicola and Dario have brought the land back to life through reforestation efforts and sustainable farming practices.

Beyond their reforestation efforts, the couple has used proceeds from agritourism programs—like eco-camps, educational courses, and apprenticeships—to further develop the farm’s infrastructure and support community development for the coastal farmers who inhabit and work the land. In addition to growing cash crops of peanuts, corn, coffee, cocoa, and passion fruit, the farm runs a primary school, where local children learn the fundamentals, as well as techniques for sustainable farming, recycling, waste management, and reforestation.

Getting Involved

Solar Energy International is one of several organizations that has helped the farm develop its infrastructure. Last March, SEI took a group of students—nine Americans and three Ecuadorians—to the farm for a five-day workshop on sustainable agriculture, permaculture, and renewable energy.

For most participants, the real highlight came on the third day, with the installation of a 100-watt photovoltaic system on the farm—made possible by students’ tuition and generous equipment donations. The farm previously installed a small 32 W solar module to charge a battery for radio communications, but the people who live and work on the farm were eager to see solar power applied in a larger format so they could better understand the technology. Due to the unreliability of grid power in the region, which often goes out for days at a time, owners Nicola and Dario have been working with SEI to implement RE solutions for the farm’s energy needs, specifically to power all the farm’s lights.

Planning for PV

Prior to traveling to Ecuador, SEI staff collaborated with Nicola and Dario on their needs. Having been to the farm on previous trips, most of the crew were familiar with the layout, which made it easier to plan for the installation.

The farm has several bamboo-thatch cabins to house the growing number of volunteers and guests. Though the amenities are basic, the cabins are equipped with overhead and reading lights that were powered by the grid. The goal was to install a solar-electric system to provide lighting for two cabins, two bathrooms, and one outdoor area—a total of 21 lights.

Working within a small budget, an existing inverter, and limited in-country equipment availability posed a challenge, but the SEI crew hatched a plan that maximized efficiency while minimizing costs. Key to the plan was LED bulbs, which use less than a third of the energy of compact fluorescent bulbs and last up to 30,000 hours. Though more costly than both incandescent and compact fluorescent bulbs, LED bulbs can quickly pay for themselves through energy savings. With the high cost of PV-made energy, the payback is a lot shorter.

By replacing the existing incandescent lightbulbs with LEDs, the crew found that the farm could power twice as many lights with the planned 100 W PV system. Even with the expense of buying new LEDs, the plan was substantially more cost-effective than trying to PV-power the incandescent bulbs.

Weather was the next consideration. Given that five months of the year are completely overcast and subject to long cloudy periods, using PV modules as the only power source would not provide the year-round reliability that the farm needed. Since a large battery bank exceeded the budget, the crew decided to take advantage of the cabin’s preexisting grid connection and devised a plan that allows the farm to manually switch the power source between the small PV system and the grid. An 115 Ah Millennium battery was used, providing up to three nights of lighting at 50% depth of discharge if the grid goes down.

Installing the System

Finding a suitable location for the array among the dense tropical flora and fauna proved challenging. The crew settled on a sunny spot not far from the cabins and bathroom buildings—one of the few clearings on the developed portion of the farm. At the equator, the sun is very high in the sky and shading is less likely during midday, so there was less need for a detailed solar site analysis.

In the classroom, Carol Weis of SEI explained to the locals how the power from the PV array goes through the controller to the battery, and then through an inverter to a manual transfer switch. She also illustrated how the grid power comes into the other side of the transfer switch. Following the discussion, the students—including the farm’s maintenance workers, who participated in the course and installation—split into three groups and got to work.

Mounting the modules. The two 50 W modules were mounted on Direct Power & Water feet on a 12-foot bamboo platform, which was high enough to minimize shading from huge umbrella-shaped saman and palm trees.

Wiring the power center. The incoming PV array got wired first into a donated MidNite Solar DC disconnect box, where the PV-to-charge-controller circuit breaker is housed. The PV wiring from the DC disconnect was run to the 10 A Steca controller. The charge controller to battery wiring was also completed through its own circuit breaker in the DC disconnect box. Wiring was then run from the battery to a 600 W inverter via a third breaker in the DC disconnect box.

On the AC side, the transfer switch was connected to the output of the inverter, which allows for the manual transfer between grid power and the PV system. Finally, wiring between the transfer switch and the AC loads was completed via an AC disconnect box.

New wiring to the cabins. Working in the developing world often means working with pre-existing wiring and equipment that may not be ideal or up to standards. The wiring on the farm was typical of rural Latin America: a jumble of indoor-rated wires running from tree to tree—pretty unsightly and unsafe. Nicola and Dario wanted the wires routed underground in conduit for safety and aesthetic reasons.

Working with PV

The finished system—which took less than two days to complete—allows the farm to manage their electricity needs by switching between sources. When the sun is shining, energy can be sourced from the PV array. During cloudy weather, or other times, like when the battery charge gets low, the farm can switch over to the grid until the battery is recharged by the PV modules. Likewise, if the grid goes down, the farm can easily switch over to the PV system and still have electricity for lighting. On the rare occasions when the cabins are not being used, the inverter can be turned off and the loads switched over to the grid to avoid unnecessary drains on the battery from the inverter, which uses 3.6 W on standby.

Nicola and two technicians from the farm took part in the class, and Sergio, the main technician, also received additional training in system maintenance and troubleshooting. Taking into account the remote location, the crew left behind extra equipment for unexpected problems—a controller, fuses, and replacement LED lamps.

After the success of the PV lighting system, Nicola and Dario are eager to power the whole farm with renewable energy, including the water pumps for filling the cisterns. Next year, SEI plans to return to the farm to install more PV systems for the cabins, and to build a pedal-powered water pump.

Access

Laurie Guevara-Stone is the international program manager at Solar Energy International, a nonprofit RE educational organization. Laurie, her Ecuadorian husband Anibal, and their son Camilo try to spend as much time as possible near the equator.

Solar Energy International • www.solarenergy.org

Rio Muchacho Organic Farm • www.riomuchacho.com

International Renewable Resources Institute • www.irrimexico.org

System Components:

C. Crane Company • www.ccrane.com • LEDs

Kyocera • www.kyocerasolar.com • Modules

MidNite Solar • www.midnitesolar.com • Combiner box

Steca • www.stecasolar.com • Controller

Techman Electronics • www.techman-usa.com • Inverter

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