Photovoltaic Power Generation - Renewable Energy: Technology, Economics and Environment - page 284

Grid

Conversion of photon
energy into potential
electron energy
(semiconductor)

Electric-
electric
inverter

El. energy
inside
the grid
Fig. 6.29 Energy conversion chain of photovoltaic power generation (el. electric; /6-11/)

Solar radiation Electric energy inside

energy the semiconductor

material

Losses. Due to the described loss mechanisms only a small part of the solar radi-
ated energy can be fed into the power grid at the connection point. Fig. 6.30
shows the most important losses throughout the overall energy flow of a photo-
voltaic plant and also indicates the respective magnitude of these losses. The
losses indicated in Fig. 6.30 are average figures which may be higher or lower in
practical operation; they refer to solar radiation onto the module surface.

Further
components

Solar cell

> 23 % > 33 % > 17 % >11 % 0.2 - 1.0 % 1 - 3 % 0.2 - 0.8 %

Losses relating to received solar energy

Fig. 6.30 Energy flow of a photovoltaic generator under Central European conditions
(solar cell losses have been assumed as minimum losses under standard test conditions
(STC); see /6-11/)

According to the diagram, the losses incurred within the actual photovoltaic
cell during the conversion of the solar radiation energy into direct electric current
account for the major share by far (see /6-2/, /6-10/). For the shown example the
approximate efficiency of the solar cell amounts to 16 % referring to the solar