We often think that modern societies were the first to use solar energy. Not true! Early cave dwellers preferred caves that had openings facing southeasterly that allowed the morning sun to warm them up without overheating in the warm months.  Native Americans in the Southwest oriented their pueblo dwellings.  So the low winter sun would keep the buildings by direct solar radiation, cliffs and overhangs blocked the sun during the summer months, helping to keep the dwellings cooler when the sun was high in the sky.

The ancient Greeks, with a climate that was sunny almost year-round, built their houses to take advantage of the sun’s rays during the moderately cool winters and to avoid the sun’s heat during the summer.  Modern excavations of many classic Greek cities show that individual homes were oriented towards the South and entire cities were planned to allow equal access to the winter sun.  It is interesting to note that by 500 B.C., when the Greeks had almost completely deforested their whole country and needed to find a reliable alternative fuel source, they chose solar energy. (more…)

Solar energy is a term that refers to the direct use of sunlight to produce heat or electric power.  The sun’s energy is plentiful, but it is thinly distributed over a large area. It must be collected and concentrated in order to produce usable power. The amount of solar radiation per unit of flat area is above 1,000 Watts per square meter.

Heat used in a solar thermal system is guided by five basic principles: heat gain; heat transfer; heat storage; heat transport; and heat insulation. Here, heat is the measure of the amount of thermal energy an object contains and is the product of temperature and mass. The higher the temperature of a substance, the more heat it absorbed. Of course, some materials require more heat to become warmer than others — this is caused by differences in so called specific heat of substances. (more…)

I just looked at the results of the poll I posted in the sidebar when I launched this blog. I ask there, what are the causes you want to live off-grid. One of the main causes is at the moment the “to reduce utility costs”. When I cast my vote in that poll I didn’t check this option. I simply don’t believe that living off the grid is a good way to reduce utility costs. (more…)

A couple of days ago I finished reading the “Walden”, a book by Henry D. Thoreau. Though it was published more than 150 years ago (in 1854), it is considered by many off-gridders as their bible and source of inspiration. When I first started reading about living off the grid, I found references to this book. (more…)

Liquefied petroleum gas (or short LPG) is a mixture of propane and buthane and is commonly used for home heating and as an gasoline (petrol) alternative for internal combustion engines. It is made from crude oil or from natural gas, so by all means it is non-renewable fuel. It cannot be obtained easily at home and is very easy to use — the gas in pressure of 6 atmospheres is liquid in room temperature. So it doesn’t need large containers prepared for very high pressures to store it.

The following article gives a good intro about this fuel. (more…)