After the discussion of angle-dependent efficiencies of the light guide and optical fibers and by considering the light intercept factor at the focus, the final transmitted solar power Pout was calculated using equation (2):

Pout =Ъл, (Фі )vg (Фі )Vf {Фі )Щ (Фі) (2)

7=0

where: rjc is the concentrator reflectivity (=0.85), гц (фі) is the angle-dependent intercept factor of the angle transformer light guide, pf (фі) is the transmission efficiency for optical fibers, I is the solar insolation, typically, 800W/m2, Д(ф^ is the ring area of the parabolic mirror between (фі) and (фі+і), and щ (фі) the transmission efficiency of the angle transformer light guide.

The theoretical analyses were confirmed by the following experimental results.

The obtained results were affected both by the irradiance fluctuations in time and mirror misalignment. The maximum measured power on the output end of the optical fiber bundle was 184W, with an efficiency of 50% and a 2,63W/mm2. The experimental results were obtained in a clear day of February of 2003. Stronger solar power can be expected in the summer time in Lisbon.