19.5
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optimum charge conditions are realized. In controllers with a boost charge facility, the
array current is switched off at a relatively high voltage once (a day) and subsequently the
voltage is kept within a narrow band as described above. During boost charging the
overvoltage is relatively high during a short period of time, accelerating the conversion of
lead sulphate into lead and lead oxide. The precise voltage settings are dependent on the
specific type of lead acid battery.
In the case of lead acid batteries, the deep discharge protection acts on the battery
voltage, in general. Because the battery terminal voltage depends both on the actual state
of charge and the internal voltage drop caused by the battery current flowing through the
internal battery resistance (see Section 19.3.2), the controller needs to act on the battery
terminal voltage corrected for this internal voltage drop. A deep discharge protection
doing so is said to have current compensation. If the voltage drop along the battery cables
(and fuses if present) cannot be neglected, separate leads (battery voltage sense lines) are
used to measure the actual battery terminal voltage.
Cables
The overall performance of PV systems is also strongly dependent on the correct choice of
the cables. We therefore will discuss how to choose suitable cables. But we start our
discussion with colour conventions.
PV systems usually contain DC and AC parts. To correctly install a PV system, it is
important to know the colour conventions. For DC cables,
red is used for connecting the + contacts of the different system components
with each other, while
black is used for connecting the − contacts and for interconnecting the modules
with each other.
For DC string cabling between modules in an array, black cables are often used because of
the poor UV stability of coloured cables. Polarity indication is done by the use of
dedicated connectors with polarity markings. An example is the famous multi-contact
connector, which can be delivered together with the flying cable as one unit.
For AC wiring, different colour conventions are used around the world.
For example, in the European Union,
blue is used for neutral,
green-yellow is used for the protective earth, and
•
•
•
optimum charge conditions are realized. In controllers with a boost charge facility, the
array current is switched off at a relatively high voltage once (a day) and subsequently the
voltage is kept within a narrow band as described above. During boost charging the
overvoltage is relatively high during a short period of time, accelerating the conversion of
lead sulphate into lead and lead oxide. The precise voltage settings are dependent on the
specific type of lead acid battery.
In the case of lead acid batteries, the deep discharge protection acts on the battery
voltage, in general. Because the battery terminal voltage depends both on the actual state
of charge and the internal voltage drop caused by the battery current flowing through the
internal battery resistance (see Section 19.3.2), the controller needs to act on the battery
terminal voltage corrected for this internal voltage drop. A deep discharge protection
doing so is said to have current compensation. If the voltage drop along the battery cables
(and fuses if present) cannot be neglected, separate leads (battery voltage sense lines) are
used to measure the actual battery terminal voltage.
Cables
The overall performance of PV systems is also strongly dependent on the correct choice of
the cables. We therefore will discuss how to choose suitable cables. But we start our
discussion with colour conventions.
PV systems usually contain DC and AC parts. To correctly install a PV system, it is
important to know the colour conventions. For DC cables,
red is used for connecting the + contacts of the different system components
with each other, while
black is used for connecting the − contacts and for interconnecting the modules
with each other.
For DC string cabling between modules in an array, black cables are often used because of
the poor UV stability of coloured cables. Polarity indication is done by the use of
dedicated connectors with polarity markings. An example is the famous multi-contact
connector, which can be delivered together with the flying cable as one unit.
For AC wiring, different colour conventions are used around the world.
For example, in the European Union,
blue is used for neutral,
green-yellow is used for the protective earth, and