Cover Image
close this bookBasic Electrification for Rural Households (GTZ, 1992, 28 p.)
close this folder3. PV systems for supplying electric power to rural households
View the document(introduction...)
View the document3.1 Central-Station Village, Power-Supply Systems and PV Battery-Charging Stations
View the document3.2 Solar Home Systems (SHS)

3.2 Solar Home Systems (SHS)

The time has now come to formulate a coherent policy for the dissemination of solar home systems. GTZ has gained extensive experience with various approaches to the diffusion of this technology, ranging from distribution by private enterprises to government-run promotion programs.

Before proceeding, however, let us first take closer look at the technical components of an SHS. Since certain of the system components have not yet been perfected, it is essential to establish quality standards and require that all future projects adhere to these norms. Minimum technical standards have already been introduced for the charge regulator and the ballast. It should also be determined whether the inability of past programs to set in motion large-scale, self-sustaining dissemination processes has been due to technical problems; this is a distinct possibility.

SHS are small-scale photovoltaic systems that are designed primarily for use in private households. They produce 12-volt direct current, and given their modest output (20 to 100 Wp) they are mainly used to operate transistorized lamps ( =fluorescent lamps equipped with electronic ballasts) and home entertainment equipment such as radios and television sets. The basic system components are a PV panel, a charge regulator, a battery and one or more lamps. *)

Especially when selecting electronic ballasts and charge regulators, it is essential to choose robust, long-lasting devices that have been specifically designed for SHS applications. In other words, "improvised" or "home-made" equipment should not be used under any circumstances. The utilization of a good charge regulator can prolong the life of the battery considerably, and this in turn has an enormous impact on the economic viability of an SHS.

In the meantime, minimum standards have been established for the charge regulator and the electronic ballast on the basis of data generated by GTZ's field projects. Among other things, they are intended to help eliminate the technical problems that are still being encountered with these components. (For example, operating problems are still being reported due to difficulties with the load disconnecting relay in the charge regulators, and these problems must be solved.) Moreover, local manufacturers must be held to the same technical standards as equipment suppliers in industrial countries: When it comes to selecting charge regulators for use in SHS, quality must not be sacrificed for the sake of "local content".

Certain components are still not suitable for local production. Thus, for example, it would not be advisable at present for developing countries to set up their own production facilities for solar cells and panels since the equipment that is used in the requisite manufacturing processes is very expensive and the processes themselves are still changing quite rapidly. The electronic devices (regulators and ballasts), on the other hand, are suitable for local production. Here the principal aim must be to significantly improve the quality of locally manufactured products, which so far has fallen considerably short of what is needed. It must be made easier for the relevant firms in developing countries to purchase electronic components; their production facilities must be upgraded through the acquisition of new machines and tools; and the qualifications of their employees, especially those responsible for after-sales service and maintenance work, must be improved. Systematic support for specific aspects of product development can also help to improve the quality of locally produced electronic components. If technical problems are to be eliminated, it will also be imperative to establish binding technical standards and monitor compliance with them. In its role as a Technical Cooperation organization, GTZ can help developing countries to address the existing constraints in all of these areas by providing information and assigning short-term experts to advise relevant government agencies and upgrade the capabilities of local electronics firms.

It might also be possible to substantially improve the quality of locally produced equipment if final assembly of the devices in question were the only part of the production process that took place in developing countries, i. e. if design, product development, specification and component procurement were handled by manufacturers in an industrialized country. With this type of arrangement, the units - charge regulators, for example - would be shipped to the developing country in the form of ready-to-assemble kits in lots of, say, 100, 500 or 1,000 and then assembled, tested and delivered to the firms responsible for puffing together the complete SHS by qualified local manufacturers.