DIODI BYPASS: they are installed in the junction box behind the solar panel and serve to safeguard a panel from possible overheating effects due to the shading of some cells as well as ensuring better productivity of the system. Such diodes areconnected in parallel relative to the panel and when there are shaded cellsthey work as an alternative to the cells themselves, ossia se i diodi sono attivi le celle sono bypassate e viceversa se le celle stanno erogando i diodi non sono attivi.

Therefore they, when they are activated (in the presence of shadows), they have a double function:

– consentono il bypass delle celle ombreggiate per evitare che le stesse fungendo da carico si surriscaldino.

– se ci sono più pannelli in serie evitano che le celle ombreggiate blocchino interamente la stringa.

The bypass diode therefore when activated protects the shaded cells from overheating and at the same time avoids (bypassandole) che poche celle ombreggiate blocchino totalmente la produzione del sistema solare.

USE: the function of bypassing the shaded cells that do not produce is all the more important the longer the string of solar panels, i.e. the increase in the number of panels connected in series; therefore whether 12V or 24V is used in a given applicationa single photovoltaic module the presence of the diode is totally irrelevant: in fact if the diode is activated bypassing the shaded cells, the panel voltage typically drops by half so it is no longer sufficient to charge the battery… per cui il vantaggio di bypassare le celle ombreggiate di fatto si perde.

BLOCK DIODES OR STRING DIODES they are used to solve any problem due to the parallel connection of strings of photovoltaic panels when one or more of these are less exposed to sunlight than others. In this case there is the possibility that these partially suck the energy from the well exposed strings. These diodes, block sayings, they must be connected in SERIES to the strings, on the output positive of each string. These diodes have the function of “non-return valve” that is, they only allow the string to supply current, preventing any energy input (forced by other strings). Con tali diodi se si mettono in parallelo stringhe con tensioni diverse si evita che quella con tensioni maggiori riversi parte dell’energia alla stringa con tensione minore garantendo in qualche modo una indipendenza tra le stringhe connessi in parallelo.

L'articolo What is the difference between bypass diodes and blocking diodes? proviene da Ocram.