Functional Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 245

Fig. 5 Parallel connection. a without blocking diodes, b with blocking diodes

The number of modules connected in series, in SMs , making up a branch, is given
by relation:

n SMs ¼ V CC = V SMn ð 6 Þ

The number of branches connected in parallel, in SMp , is given by relation:

n SMp ¼ n SM =

ð Þ

n SMs 7

There is a probability, that not all solar modules will receive the same amount of
solar irradiation, due to shadows. There is a risk of overheating and permanent
damage when a single SM within a PV panel is affected by shadow. Bypass diodes
are used in PV panel to protect the SMs from overheating (Fig. 4 ).
When connected in parallel several reverse circulation currents can occur on
shaded modules series. To avoid the reverse circulation is necessary to use the
blocking diodes (Fig. 5 ).
The algorithm for photovoltaic panel choosing is shown in Fig. 6 .

B. Batteries capacity

Battery system design and selection involve many decisions and tradeoffs.
Choosing the right battery for a PV application depends on many factors. In PV
systems, lead acid batteries are most common due to their wide availability in

many sizes, low cost, and well-understood performance characteristics. In a few

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