What makes "appropriate technology" is determined by context. Therefore, none of these are absolute - they are simply common features that make a technology "appropriate" to a world where many suffer a lack of basic necessities, a lack of money, and lack of equipment and technological expertise. They are also technologies that have a gentle impact on the earth:
* Small, as in Small is Beautiful. Small often means affordable and adaptable, and puts the control in the hands of the users. Small also means local, which offers benefits in resilience;
Few moving parts - less to go wrong (similar to the KISS principle).
Can be built locally;
Easily repaired, by local people with locally available equipment;
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.