Solar energy conversion apparatus

A method of generating solar-thermal energy by irradiation of an solar-thermal receiver apparatus by a solar concentrator, including the steps:

• a.) providing a solar-thermal receiver apparatus having a first substantially transparent glass receiver structure;
• b.) providing a second substantially transparent glass receiver structure, so that a flow space is provided between the first and second glass receiver structures;
• c.) providing an optical concentrator for concentrating radiation into the interior of the flow space;
• d.) flowing a heat transfer liquid within the flow space, the radiation transmitting at least partially into the liquid, wherein absorbing media is provided in the liquid in a predetermined mixture for optimizing performance of the solar-thermal apparatus, wherein the composition of the mixture is altered as a temporal function of local conditions.

A solar-thermal receiver apparatus, comprising:

• a.) a first substantially transparent glass tube, the first tube having a linear central axis;
• b.) an inner cylinder coaxial to and within the first tube, so that an annular flow space is formed between the first glass tube and the inner cylinder, the annular flow space having an outer surface defined by the interior surface of the first tube;
• c.) coupling means for both supplying and removing a heat transferring liquid to the annular flow space;
• and,
• d.) first absorption means for providing absorption beneath the outer surface of the annular flow space, wherein radiation is at least partially transmitting through the annular flow-space so as to be absorbed by first absorption means;
• e.) second absorption means located interior to the annular flow space, the second absorption means comprising a photovoltaic array.