SOLAR POWER GENERATION
Introduction.
Over the last 50 years, Solar Photovoltaic (PV) systems have evolved into a mature, sustainable and adaptive
technology. This technology is improving as solar cells increase in efficiency and modules attain better
aesthetic appearance. As a result, solar power is gaining more acceptance and is becoming an increasingly
cost-effective and clean alternative to conventional energy sources. Sunlight has an energy content of 1kW
(1,000 watts) per square meter. A typical Solar Panel achieves between 10% and 15% efficiency conversion.
How it Works.
Solar Power generation systems are made of Photovoltaic cells and Power inverters. The photovoltaic cells
utilise the power of sunlight to convert photons to clean DC (Direct Current) electricity. The Electricity
generated by the Solar Cells is then fed into a Power Inverter (PV inverter) that converts and regulates the
DC source into usable AC power. This AC power can then be used locally for specific remote equipment,
residential homes or fed directly back into the power grid and used as clean, environmental energy.
Solar Panel
Solar Cell
Schematic
Symbol
Symbol
Solar Strings & Arrays.
An individual panel is made up of a number of photovoltaic cells connected in series. The voltage output of a
Solar Panel is defined by the number of individual cells in series. When multiple panels are connected in
series, it forms a ‘string’. When ‘strings’ are connected in parallel, it forms an ‘array ’.
Solar Cell
Solar Panel
PV
Fuses
PV Invertor
Collector
or
Combiner
Box
PV Array
AC
DC
PV String
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Web: www.swe-check.com.au
Phone: +61 3 9521 6133
Fax: +61 3 9521 6177
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SOLAR POWER GENERATION
The Need for Circuit Protection.
As the installations and demand for PV systems increases, so does the need for effective electrical protection. PV
systems, as with all electrical power systems, must have appropriate overcurrent protection for equipment and
conductors. Globally there is a push for utilizing higher voltages (trending to 1000Vdc and above) to achieve more
efficiency.
When Protection is Required.
PV systems that have three or more strings connected in parallel , need to have each string protected . S ystems that
have less than three strings will not generate enough fault current to damage the conductors/equipment and
therefore do not present a safety hazard as long as the conductor was sized properly based on local code
requirements. Where three or more strings are connected in parallel , a fuse on each string will protect the
conductors from damage and eliminate any safety hazards. It will also isolate the faulted string so that the rest of
the PV system can continue to generate electricity.
PV Array
PV Fuses
PV String 1
+
-
-
+
-
PV array
junction box
+
PV array main switch
PV String 2
+
-
-
+
-
+ DC
+
AC
Bypass diode
PV String xx
+
-
PV Fuses
-
+
-
Overvoltage
Protection
+
PV Panel
Fuse Protection of PV Strings.
Operating conditions for fuses are actually more severe when fault currents are low than when they are high ( in a
circuit where breaking is required under direct voltage ) . Melting times are long and breaking is arduous. For this
reason, manufacturers have created a range of fuses that are specifically designed and tested to safely protect PV
systems with high DC voltages and low fault currents.
DCM Series 600 VDC
100mA to 30A Ratings
CHPV1 Series
1000 VDC Fuse Carrier
(Gangable)
CCP-1-DCM Series
Fuse Switch Disconnector
80 VDC
PV..A10F Series 1000 VDC
1A to 30A Ratings
Email: sales@swe-check.com.au
Web: www.swe-check.com.au
Phone: +61 3 9521 6133
Fax: +61 3 9521 6177
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SOLAR POWER GENERATION
PV Surge Protection.
The unique nature of PV installations make them vulnerable to over voltages and
surges from lightning strikes and static discharges. These surges need to be
intercepted before they take down the entire system by damaging the PV arrays,
charge controller/inverter and combiner boxes.
BSPH Series
Fuse Protection for PV Arrays.
Depending on the desired capacity of the Photovoltaic (PV) system, there may be several PV sub-arrays (each subarray consists of multiple strings) connected in parallel to achieve higher currents and subsequently more power.
A fuse link on each sub-array will protect the conductors from current faults and help minimise any safety hazards.
It will also isolate the faulted sub-array so that the rest of the PV system can continue to generate electricity. If a
number of sub-arrays are subsequently combined then a further fuse link should be incorporated. This would be
termed the array fuse link.
A range of NH size fuse links specifically designed for protecting and isolating photovoltaic array combiners and
disconnects. These fuse links are capable of interrupting low over currents associated with faulted PV systems
(reverse current, multi-array fault).
It should be remembered that the characteristics of PV modules vary with module temperature as well as
irradiance level. In operation fuse links are influenced by ambient temperature.
We stock a wide range of Solar circuit protection devices including fuses, blocks & carriers.
Why use fuses instead of circuit breakers?
PV..ANH1 Series
1000VDC
32A to 160A Ratings
SD1-D-PV Series
1500VDC
1 pole block
PV..XL Series
1000VDC to 1500VDC
50A to 630A Ratings
There are a few reasons why to use fuses instead of
miniature circuit breakers (MCB’s) for DC;
1. Fuses are smaller, cheaper and more reliable.
2. Fuses can easily reach high DC voltage ratings of
up to 1500VDC.
3. Fuses have a higher DC breaking capacity up to 30kA
whilst MCB’s have only break several kA’s.
4. No degradation over the time.
5. Much lower tolerance of I/t characteristics.
6. Good protection of panels against overheating in
case of reverse current.
4122038 Series 1 Pole
Fuse Switch Disconnector
1000VDC
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Web: www.swe-check.com.au
BFH Series 3 Pole
Fuse Switch Disconnector
250VDC to 400VDC
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Fax: +61 3 9521 6177
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