This is the word that is starting to be used for the growing business of making and using solar cells for energy production. Solar cells (or photovoltaic cells) are semi-conductors - they're made of wafer-thin layers of silicon and other materials - which means they have the advantage that they use very little material, and operate without moving parts.

The major difference between solar cells and micro-electronics is their area. Solar energy in space near the Earth has an intensity of about 1.4 kW per square meter. Near the equator on Earth it's about 1 kW/sqm at mid-day, and at higher latitudes it's typically about 500 W/sqm. So to collect large amounts of energy you need large areas of solar cells. For example, a million kW, one Gigawatt (GW), which is enough for about 1 million people at the rich countries' level of consumption, would need about 1 square kilometer of desert near the equator at mid-day if the efficiency was 100%.

However solar cells' efficiency is about 10% - it varies from about 5% to about 20% according to the type of cell. So in fact about 20 square kilometers would be required for 1 GW. Thus to supply electric power for hundreds of millions of people, which is necessary if solar cells are to supply a significant share of world energy needs, thousands of square kilometers of solar cells will be needed - "macro-electronics". Although this sounds a lot, there will be no problem in producing such large quantities of solar cells, once the costs are competitive with other energy sources, because the amount of material used is so little.

Luckily, the semi-conductor industry is the most dynamic field of manufacturing industries. Technological innovation is racing along as fast than ever, and the cost of solar cells has been falling for years.