(This article is dated but is presented here for historical interest.)

Terrasol's Experience with Pilot Projects

Presented at the Benjamin Linder Memorial Conference
on Alternative Sources of Energy and Rural Electrification in Central America
November, 1989

By Roger Lippman and Barbara Atkinson


Terrasol is an international network supporting solar energy development in Nicaragua. The group collaborates with Nicaraguan organizations, providing technical and material assistance. Terrasol's primary work to date has been with rural photovoltaic lighting systems. This paper reviews Terrasol's work to date, discussing its technical approach and its relationship with other organizations, both within Nicaragua and in the international solidarity community. It also discusses the recent installation by the authors of a remote photovoltaic system, as well as the process of training Nicaraguans to install and maintain systems. Questions on lessons learned, technical issues, and future directions are raised for discussion by conference participants.


Terrasol is an organization dedicated to the implementation of solar energy technologies in Nicaragua. It was founded by several Nicaraguan and international solar energy proponents. The network in the U.S. first consisted of supporters of Barbara Francis, a long-term U.S. volunteer in the solar unit of the Nicaraguan Energy Institute (INE - the national utility). It has now grown to include members in the U.S., Australia, Europe, and Africa.

Terrasol merges two significant strains in the U.S. progressive movement: anti-interventionism and environmentalism. Historically, the people working in these two areas have been more or less oblivious to each others' work. In recent years, however, the crises in both realms have forced each group to become more aware of the other. Terrasol unequivocally supports Nicaragua's right to self-determination and opposes foreign intervention. Additionally, we are committed to helping Nicaragua develop its energy sector in a sustainable, environmentally sound manner.

At present, Terrasol's primary work is the application of photovoltaic (PV) systems in Nicaragua. Terrasol has also been involved with projects on solar ovens and solar grain drying.

Photovoltaic panels convert sunlight directly into electricity. They are fairly expensive on the world market, though the price continues to drop. At present the panels themselves cost about $5.00 per peak watt, which is somewhat less than the cost of a nuclear plant and somewhat more than the cost of a coal plant. Of course, PVs lack the adverse environmental impacts of conventional technology, and they can be brought into service quickly. In overdeveloped as well as lesser-developed countries, they are generally considered a cost-effective alternative to extending power lines to off-grid areas. Their cost-effectiveness will continue to improve as technology advances in the coming decade.

Before the Terrasol network was formally created, some of its members installed photovoltaic lighting systems at two remote agricultural cooperatives. In the summer of 1988, the authors received a request for solar lighting from another Nicaraguan co-op. In preparing for that installation, we studied the experiences of others who had used photovoltaics in Third World locations and incorporated those experiences into the design of our system. When we went to Nicaragua to install our system, in October, 1988, we also visited the two previous PV installations and analyzed their strengths and weaknesses. The result, as described below, was an improved system design as well as a more effective relationship with co-op members and their supporters in the Nicaraguan development community. The several PV installations subsequently sponsored by Terrasol have benefited from these lessons and further improved our ability to operate effectively.


Because of their high capital cost relative to most conventional sources of electricity, photovoltaic systems make sense primarily in remote locations far from the power grid. Thus, six of the seven systems installed by U.S. volunteers have been at rural sites.

Most of the systems have been installed in the cooperatives' community buildings, such as a school, dining hall, or other community center. Because most adults work all day, and darkness comes between 5 and 6 P.M. year around, evening lighting facilitates activities such as literacy classes or community meetings that would not otherwise be possible.


A typical system consists of the following components: PV panels. Peak capacity of 30-40 watts. Lights. Fluorescents are preferred, using conventional light tubes with special 12 volt DC fixtures. Wattage is normally equivalent to that of the PV panels. If incandescents are used they are 12 volt DC bulbs. Battery. Twelve volts, deep cycle if possible (not available in Nicaragua), or heavy duty (e.g., diesel light truck) otherwise. Control box. Includes a voltage regulator, discharge limiter (shuts off the load when the battery voltage drops below a pre-set level), an analog voltmeter, status LEDs to indicate charging and low battery, and a separate switch for each light. The box is designed to be weatherproof and insect-proof. Cables. The PV panels come with a cable attached. In a typical installation this reaches to the control box. If the distance from the controls to the lights is not excessive, 12 gauge non-metallic-sheathed cable is satisfactory for the fixture circuits. All wire connections to the above components are color-coded and fitted with unique terminals to prevent incorrect connections.

Components of Terrasol's PV lighting systems are matched to allow the system to operate normally (2-3 hours per night) for 5-7 consecutive cloudy days. If voltage drops below 11.5 volts, the discharge limiter will automatically shut the lights off to prevent battery damage from excessive discharge. Fortunately, such lengthy periods without sunshine are uncommon where we have installed our systems.


The installation at this cooperative was done with the cooperation and assistance of INPRHU, the Instituto de Promocion Humana, a private, non-profit Nicaraguan agency that supports development and training at a number of rural cooperatives. We were also assisted by the Department of External Cooperation for the second region, based in Leon. The members of the co-op requested lighting for a school building so that they could hold night classes for both adults and children. The women's sewing cooperative also wanted to work at night. The co-op had requested a generator, but there was little hope that this would be available in the near future. We observed that other co-ops with generators were unable to use them when the gasoline or diesel ran out, since it was difficult and expensive to obtain fuel at remote sites.


We were aware that previous installations at other co-ops had been done quickly and without enough training to prevent problems. While some people in rural Nicaragua have basic mechanical skills, there is little understanding of electricity. In one case people had added components that overloaded the systems or caused short circuits. (This was done both by co-op members and international workers). Simple repairs were not done because members who had worked with the installers had moved away or been called for military service, leaving the systems unmaintained.

The authors tried to improve this situation in the Santiago Arauz installation, recognizing that we would be at the co-op for only a short time. When we arrived at the site, we asked the members to select several people to work along with us. They chose three: a man who was one of the founders of the cooperative, and two women who worked most of the day near the chosen schoolhouse site. We first explained the function of each component as well as what would be required to maintain it. We also consulted with the members on where the two light fixtures would be located, and they practiced removing and inserting the tubes.

By dusk the first day we had successfully provided light for one room. That evening we held a class, to test whether the system gave sufficient light, as well as to explain its operation and maintenance to the entire community. The next day, after we completed the installation, we took the members on a tour of its components, with the people who had worked with us explaining it to the others.

System maintenance is minimal: add rainwater to the battery occasionally, change fluorescent tubes as needed, and keep the kids from throwing rocks at the PV panel. A pre-school child accepted the latter responsibility.

Before we left, we drew a circuit diagram and simple instructions for operation and maintenance, written in Spanish. While the residents may not comprehend all of the written material, another visiting technician, Nicaraguan or international, will readily be able to understand the system. In the future, a complete set of instructions and a schematic diagram will be placed inside the control box, and another will be given to co-op members.

We felt that the hands-on involvement of leading co-op members contributed greatly to the group's acceptance and understanding of the system. The system was recently inspected by a Terrasol delegation, almost a year after installation, and it was functioning without any problems.


As we have gained experience with the available PV system equipment and the conditions under which it is used in Nicaragua, we have attempted to standardize the system format.

*We have a strong preference for fluorescent lights over incandescent, since fluorescents are more efficient. To save money, we use conventional tube-style lamps, which are available in Nicaragua. Much more efficient compact fluorescent lights are now available outside of Nicaragua, but the price remains relatively high. With increased volume of production, these should become more competitively priced.

*We favor the use of sealed, deep cycle batteries in PV systems. Deep-cycle batteries are far superior to conventional automotive batteries at a comparable price, since they can be deeply discharged and recharged numerous times. They last 5 to 10 years in a PV system, compared to conventional batteries that last 1 to 2 years. Unfortunately, deep-cycle batteries are not produced or sold in Nicaragua. In the future, such production needs to be investigated. In the meantime, we try to supply deep-cycle batteries from outside of the country, since many sites are so remote that battery replacement is very cumbersome. If conventional batteries must be used, the maintenance-free sealed type is preferable. In rural Nicaragua the proper water for filling batteries may not always be available. Unfortunately, sealed batteries are not available in Nicaragua either.

*Wiring should be encased to protect it from adverse environmental impacts, especially insects.

*The control box should be well-sealed. The discharge limiter is critical to protect the batteries from being discharged. A modest number of indicators is useful to inform the users of the system status. Each light should have its own switch, to conserve electricity if not all of them need to be on.


A. Site Selection

Terrasol considers it important that the Nicaraguan development agenda be defined by Nicaraguans, not by internationals, however good their intentions. After a very positive experience working with INPRHU, Terrasol signed a formal agreement with INPRHU to supply technical assistance and PV equipment for co-ops to be selected by INPRHU. Selection will be based on need as well as accessibility -- it is important that technicians be able to reach the sites to maintain the systems. Since the systems are pilot projects, accessibility is also valuable for training and publicity purposes. Of course, there is an unfortunate tradeoff since the most remote sites are the least likely to have other electricity sources available.

B. Maintenance and Installation

Terrasol has had difficulty maintaining communication with some of the more remote PV sites. One of our long-standing goals has been to train one or more Nicaraguans to maintain existing PV systems and to install complete new systems. We have begun working with a capable person, and we are now teaching him how the systems function and how to work with them. When he has been trained, he will regularly check up on existing systems. A communication system will be set up for reporting problems. As we are able to provide equipment for additional ones, he will do the installations, perhaps working with an international volunteer.

C. Networking

Since the installation described above, Terrasol has established cooperation with several Nicaraguan institutions interested in solar energy. Terrasol's most recent installation was an opportunity for members of these groups to work together.

The groups now collaborating are: INPRHU; DINOT, the research branch of the National Engineering University (UNI); ECAMI, a private telecommunications company using photovoltaics for repeaters; the University of Central America (UCA); and the Electronics Engineering Department of the UNI. Together with a Terrasol volunteer from the U.S., Marco Buoncristiani, they installed a system that lights a warehouse at an INPRHU-supported cooperative.


Early this year, Terrasol joined several other U.S. groups in forming the Rural Energy Coalition (REC). The groups have all been active participants in on-site development of decentralized energy systems in Nicaragua. Through the coalition, the groups collaborate and support each other's projects. The membership includes Rural Electrification Support Project (small hydro), Power to the People (small hydro), and the Nicaragua Emergency Generator Project (diesel generators for hospital backup power). The group is a sponsored project of tecNICA, the largest U.S.-based technical support project for Nicaragua.

Terrasol is also a participant in the material aid project of EPOCA, the Environmental Project on Central America. The project supports the work of several environment- and energy-oriented organizations, including the Nicaragua Windmill Repair Project, Integrated Pest Management, and Campesino a Campesino (agricultural training).


Terrasol is interested in approaching other international Nicaragua solidarity organizations, such as sister city groups and construction brigades, to propose collaboration. We would ask that these groups incorporate photovoltaics into their support work for new construction or other community development activities. In kind, we would offer technical support in design, procurement, and installation of PV systems. An advantage of working with such groups is that they often have ongoing relationships with the particular communities they support, so that long-term system maintenance is facilitated.

We are also considering the use of PVs in Nicaragua for refrigeration at health centers, as well as for pumping water for irrigation. Such an expansion of activity will depend both on Nicaraguan interest and on outside funding larger than Terrasol's current resources.


We are very pleased with the development of the network of organizations within Nicaragua promoting solar energy. Their involvement and enthusiasm is essential to the success of any internationally-aided project. Decisions on site selection, training of technicians, and ongoing maintenance should rest squarely with the Nicaraguans. The ultimate goal of such "technology transfer" is as much self-sufficiency as is possible under the current economic situation.

Terrasol views the current phase of its work as a pilot project. By no means have we concluded that small photovoltaic systems at numerous sites are the best approach to rural electrification in Nicaragua. We hope that our experience will provide guidance in answering questions that have already been raised by our work. Developments in PV technology as well as cooperation of friendly governments will be crucial in answering some of these:

*Given their cost and the fact that they come from foreign sources, are photovoltaics a viable energy resource for Nicaragua?

*Should we aim for larger scale project, with significant international funding?

*Rather, or additionally, should we experiment with a different technology?

*How can we work best with Nicaraguan the government, given its severely limited resources?

*What is the evolving role of internationals in this process?

We sincerely hope that this conference serves as a forum for open discussion of these and other issues related to independent renewable energy generation in Nicaragua.

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