The experimental setup was composed by two BISOL BMO255 mono-crystalline PV modules, each with a nominal power output of 255 W, KIMO SL100 portable solarimeter, TFA sinus weather station for measuring the ambient temperature and wind velocity, and Agilent 34970a data acquisition/switch unit with six temperature sensors of the J type for measurement of the PV module temperature.

In addition, a third solarimeter tube was placed at 0.20 m above the ground to measure the transmitted radiation (Tr) through the vegetative canopy.

A Solarimeter (Daystar meter, DS-05A) was used for measuring the incident solar radiation in W/[m.sup.2].

Radiation interception was measured with one tube solarimeter (70 cm) per plot (Marcos, 2000).

2) was measured with a Kipp and Zonen Type CM10 Solarimeter (Delft, Holland); 73% of this was transmitted into the glasshouses.

A tube solarimeter to measure radiation among plants.

Interception of total incident solar radiation (spectral response 0.35B2.5 Fm) was recorded in each plot by a single tube solarimeter (Type TSL, Delta-T Devices, Cambridge, England) placed diagonally across the two innermost rows, at ground level.

Using tube solarimeters to measure radiation interception by crop canopies and to analyse stand growth.

One half (12 by 1.6 [m.sup.2]) of each plot area was allocated for growth-analysis sampling and for assessment of crop development, and the remaining half for measuring combine grain yield and radiation interception, using in situ solarimeters and hand-held ceptometers.