For centuries flat solar panels were the simplest, and at the same time the most basic way that Man used to collect solar radiation directly. It later asserted itself as an attractive source of energy as it was economical, non-pollutant, rational and available to everyone. The sophistication of the collector which has occurred in recent decades, rather than sorting out the problem of its low performance, introduced more fragile components into the equipment:
Absorption plates and/or transfer tubes in metals with a high risk of corrosion;
Paints whose durability was questionable;
Sealants sensitive to degradation by solar radiation;
Unsafe or even dangerous defrost systems.
Owing to said fragilities and the condensation which occurs inside, as a general rule a panel installation does not have a working life of more than six years which is why it was almost totally abandoned in the 1980’s.
In the last two decades, with the constant increase in fuel prices and the appearance of a new environmental awareness, there has also been demand for new solar radiation direct collection processes.
The vacuum tubes and the concentrating collectors (CPC) were two examples of this drive. Both outperform those of the 1st generation but maintain, or even exacerbate, the factors which reduce their durability. With usage conditions which were the same as those of the 1st generation, as a rule these collectors have an even shorter working life, with the exception of the vacuum tubes which were the sole feature to evolve technologically.
No system from this generation can resolve – except with enormous collection areas – some of the following whims of nature: