Page 48 - RSE - Results of the Apollon Project

Results of the APolloN PRoject ANd coNceNtRAtiNg PhotovoltAic PeRsPective

APOLLON Progress with Respect to the State of the art

Under APOLLON, a wider signifcance was attributed to the tracking issue, not just meaning the tracking of the
sun but even the capacity to track the maxim power point (MPPT) of the module. A new technological approach is
proposed that transfers the tracking issue at the module level, leading to the development of Intelligent Concentrating
Module (ICM) technology. Two different tracking strategies have been considered in the APOLLON project, for 1st and
2nd generation CPV systems, respectively:

w The optimisation of existing mechanical construction and electronic tracking controls as a function of tracker:
i. size;
ii. load-capacity;
iii. stability;
iv. stiffness and material consumption.

w The design and implementation of “intelligent concentrating modules” (ICMs) with Internally Integrated
Position Sensitive Detectors and Maximum Power Point Tracking Devices.

The design of “intelligent concentrating modules” (ICMs) is a real innovation on CPV technology and the relevant
concepts will described in detail in the next paragraph.
APOLLON Progress on PSd tracking Control

The PSD sensor unit developed by RSE solves the problem described in previous paragraphs, because it is
integrated into the CPV modules (namely, it is installed in the module backplane within a waterproof box) and it is
a low cost device. It is composed of four main components (see Figure 52):

p CCd sensor with output projection data, which is a CCD that can provide the projection of light on the
reference axis of the sensor;
p Optical collimator which transfers a bright spot on the sensor surface;
p Electronic board which acquires and processes CCD data and outputs the misalignment errors ERR_AZs (°)
and ERR_ELs (°);
p Waterproof box.

FiguRE 52. PSD RSE sensor unit consisting of a waterproof box, optical collimator, CCD image sensor and electronic
processing board (patent pending)

CCD image sensor Electronic processing board

Optical
collimator

Outdoor waterproof box

The CCD sensor is a special commercial low cost CCD, consisting of an electrical charge matrix (pixels). It is
equipped with an electronic board that is able to directly provide the projection of the light on orthogonal axes x-y
(see Figure 53). This circuit provides an output voltage proportional to the electric charge that is stored along the
rows and columns of the sensor. An analogue to digital converter quantizes the light in 256 levels (8 bit if set) or 1024
(when set to 10bit) and converts the value in digital format.

47