Solar power system for photovoltaic fuses
1.By system size
- Household photovoltaic system (roof photovoltaic)
This is the basic application scenario for photovoltaic fuses. In domestic photovoltaic systems, a fuse is usually installed between photovoltaic module and the inverter, with two main tasks: to protect the internal circuit of the home from the backflow shock caused by the photovoltaic array, and to quickly cut the abnormal current to prevent overheating and even fire when the assembly shorts out. Such systems typically use low-current specifications (such as 1A to 30A) and are compatible with string inverters.
- Industrial and commercial distributed power station
In rooftop or ground distribution systems in factories, malls, schools, hospitals, etc., fuses are usually installed between panels and the combiner box to protect the combiner box and the entire DC line. Due to the complexity of electrical systems in an industrial environment, the breakability and response speed of fuses are more demanding and appropriate specifications need to be selected.
Large terrestrial photovoltaic power station (centralized system)
Large power plants have more components and more systematic fuse configuration. In addition to deploying fuses at the output end of each string, multiple layers of protection are required between the combiner box and the inverter and on the inverter's DC input bus. The system can be selected for high current specification (e.g. 200A to 500A), adapts to centralized inverters, and requires a crushing capacity of more than 50kA.
2. By system structure
Serial photovoltaic systems
This is the prevailing architecture for distributed photovoltaics. Each positive or negative output terminal a string must be connected to a fuse (or use an integrated fuse terminal) for single-string level protection. When one string malfunctions, the fuse melts quickly, isolating the malfunctioning branches without disrupting the operation of other normal strings. String inverters usually have the ability to detect string currents and can be used to quickly locate and replace fuse faults.
Centralized photovoltaic system
Multiple strings are first aggregated and then connected to a centralized inverter. In this architecture, the fuse needs to cover two levels: a serial branch protecting the combination box, and a bus protecting the DC input end of the inverter. Some systems will also use smart fuzes that can effectively address the risk of failure such as branch backflow and small multiple overloads.
Integrated photovoltaic energy storage system
In the photovoltaic + energy storage system, photovoltaic fuse needs to protect not only the DC side of the photovoltaic system, but also the protection scheme of the energy storage system. The charge-discharge circuit of the energy storage battery pack also requires overflow protection and short-circuit protection. Photovoltaic fuses and energy storage fuses together form a complete DC side protection chain in the DC combination link.
3. By Battery Technology Type
- Crystalline silicon battery system (including monocrystalline silicon and polycrystalline silicon)
Photovoltaic fuses have wide adaptability to crystalline silicon cell systems and provide effective overload and short-circuit protection for conventional crystalline silicon modules and silicon modules. Especially when multiple series are connected in parallel to the same MPPT channel, the fuse can prevent one series fault from causing other series current to flow back.
- Thin Film Battery System
Thin-film batteries have different electrical characteristics from crystalline silicon batteries and have relatively small short-circuit currents. Ordinary fuses may not work reliably in the event of a malfunction. Aiming at this characteristic, the special PV DC fuse is optimized, which effectively cuts off the low voltage fault current and provides adequate protection.
4. Applicable systems in special circumstances
- High-altitude photovoltaic power station
In high altitude areas with thin air and poor heat dissipation conditions, the rated current of fuzes needs to be reduced according to the environmental carrying capacity curve. Photovoltaic fuzes have a wide range of temperature adaptability (usually up to -25 ° C to+70 ° C or even+85 ° C) that enable them to withstand such extreme environments.
- High-temperature environmental power station (e.g. desert photovoltaic base)
When the ambient temperature exceeds 40 ° C, the current carrying capacity of the fuze will decrease, and a model with a higher rated current or a enhanced heat dissipation design should be selected. The weather resistance design of photovoltaic fuses can resist ultraviolet light, high temperature, high humidity, etc.
- Water photovoltaics (complementary fishery photovoltaics, floating photovoltaics)
With high humidity and salt fog corrosion, the protection level and corrosion resistance of the fuse shell are required. Photovoltaic fuses usually use flame-retardant materials (such as PA66) as a cover with a protection rating not lower than IP2X, and some products can achieve a higher level of protection.
5. Classification by voltage level
- 1000V DC system
This is the most mainstream voltage level for photovoltaic systems and is used in most distributed household and commercial systems. The corresponding photovoltaic fuse is rated at DC1000V with a rated current range of 1A to 30A (string level) or higher (bus level).
- 1500V DC system
With the popularization of high-power components, the proportion of 1500V systems in large terrestrial power stations is increasing rapidly. The corresponding photovoltaic fuse requires a rated voltage of DC1500V, with a breakage capacity of 20 kA-25 kA for some products.
