DW: Worldwide, around two billion people live without electricity. What prospects are there for getting power to them?

Peter Adelmann: In these rural regions solar energy is normally the most cost-effective resource for light, radio, television and charging mobile phones. Photovoltaics is growing here continuously, up to 25 percent per year, also due to the low cost of solar panels.

For the past three years we have seen the trend in these regions for so-called 'pico solar systems'. These very small systems have a small solar panel, a small battery and a very efficient LED lamp. The system is based on a very low consumption of electricity. The LEDs require, by comparison, only one-third of the energy of an energy-saving lamp and only a fraction of the energy of a standard light bulb. That means they need hardly any electrical energy to make a bright light. Also, televisions today are, due to LED technology, extremely economical and require about a fifth of the energy older models needed.

Are these efficient devices being bought in these regions?

Yes, that is a strict requirement. They invest perhaps $5 more in the LED-lamp itself, but at the same time they save perhaps $25 on the solar system, because batteries and solar panels can be relatively small. Most suppliers offer such packages.

Who is selling these pico solar systems?

Small dealers receive the systems from wholesalers and sell them to the people on location. This year, approximately 2.5 to 3 million of these pico systems will be sold. This young market is just developing and is growing quickly with a huge potential. About 400 million households worldwide have no connection to a power supply, so we are just at the beginning.

Who is developing these coordinated systems?

They are predominantly start-up companies, which mostly produce in Asia, but have their headquarters in industrialized countries. The market leader is based in Australia. Other strong providers come from America and there are also a couple of very active companies in Germany.

What changes are occurring in countries due to these small solar systems?

There are considerable changes. Kerosene lamps are expensive, costing a family perhaps $10 a month. Besides, the light is weak, it achieves a light intensity of only 20 lumen, a LED lamp from a typical pico system emits light of 100 or sometimes 200 lumen.

Beyond that, kerosene lamps emit a large amount of soot and fumes. According to the UN, many millions of people die every year from the fumes in their homes. Also, there is a high risk of fire. In Ethiopia, for example, around three percent of households are burned down each year due to fires, which were mostly started by kerosene lamps, but sometimes also due to cooking.

Furthermore, through electric light one achieves more in education. Children who mostly work in the fields during the day can study in the evenings and adults can attend a night school.

What role will the piko systems have in electrification in the future?

The pico systems cost between $30 and $80. As a rule, families can finance that without credit. It equates to the amount spent for lamp oil for a few months. The electrification of a whole village with a local electricity network is considerably more expensive by comparison. Such a connection costs at least 2,000 euros ($2,608), but, on average, it is more like 5,000 euro ($6,519), per family.

The electrification of rural areas with these small systems is economical and therefore a real option. I am sure that in the next few years many people will get their electricity in this way. I hope that by 2020 it will be many hundreds of millions of people.

Peter Adelmann has 30 years of expertise in decentralized electrical power supplies. He is Professor of Photovoltaics at the University of Applied Sciences in Ulm (Hochschule Ulm) and founded the Institute for Decentralized Electrification in Ulm.