Views: 4 Author: Site Editor Publish Time: 2021-12-08 Origin: Site
With the advancement of battery technology and module packaging technology, the power of photovoltaic modules has become higher and higher, 400Wp+ modules are in the ascendant, and 500Wp modules have entered the market. The internal logic behind this is still the industry's pursuit of low cost of electricity (LCOE), which is used to compare the cost of photovoltaic power generation with other forms of power generation (especially thermal power), and determines the long-term profitability of a power station. High-power components can reduce the cost of BOS (system balancing components), which in turn promotes the decline of LCOE, and has a broad application space in the coming era of parity Internet access.
The connector is a kind of auxiliary material of the photovoltaic module and the key component of the DC side connection of the power station. From the perspective of the connector, how do you view the impact of component power increase on power station owners?
Increase in current
Even if it is a 500Wp component, its system voltage will still be 1500V, so the impact on the components is mainly reflected in the current. At present, the working current of the maximum power point of the module (under STC environment) is about 9.3~11A. Of course, some companies make 500Wp component current around 17A, which involves the trade-off between large current and reducing system loss.
The component current involves many current-carrying components, such as photovoltaic junction boxes, photovoltaic connectors and cables. Generally speaking, under normal circumstances, the current increase in current has a small impact on the components, and the relatively large impact is the junction box and its internal diodes. Solving heat dissipation is the most important problem. If the component current reaches 17A, the corresponding junction box current needs to be above 20A. The current-carrying capacity of photovoltaic connectors is generally about 30~40A, and the increase in module power has almost no effect on it. Take Stäubli MC4-Evo2 as an example. When matched with a 4mm2 photovoltaic cable, its rated current can reach 45A, which not only meets the current requirements of a single component, but also can meet the confluence requirements of up to 3 strings.
Of course, power station designers usually calculate the maximum current that connectors and other components can withstand in the case of a short circuit based on the component current. If the component current reaches about 15A, some connectors with a nominal 30A cannot meet the requirements.
The amount of photovoltaic connector
In a photovoltaic power station, photovoltaic connectors are widely used in scenarios such as modules, inverters, and engineering sites. As the power of the modules increases, the amount of photovoltaic connectors also decreases. Take a typical 1MW photovoltaic power station as an example. The system uses 400Wp modules and 80kW string inverters (12 circuits). It is designed as 12 square arrays, each with 18 strings, then we can calculate The number of connectors required is about 2,952 sets, which is about 600 sets less than the previous 300Wp components. This also means that the power plant owner's early equipment investment costs are reduced.
The technical risks of photovoltaic connectors are embodied in various aspects such as quality, application, safety, and operation and maintenance, and they will affect the income of power station owners to some extent. Generally, we can examine the relationship between connectors and power plant revenue through two perspectives.
Connector failure vs power plant revenue
The Solar Bankability Project funded by the EU Horizon 2020 program aims to establish a professional risk assessment method based on existing research and collected actual failure data of photovoltaic power plants. The project risk analysis tends to assess the economic impact of technical risks and how it affects the business model and the cost of electricity. CPN (cost priority number) is a coefficient used to measure economic impact. The unit is €/kWp/year. It corresponds to the RPN (risk priority number) in the classic FMEA model. It is a method of looking at risk from a cost perspective. While ranking the risks, the economic losses corresponding to the risks are also given. Among the Top20 technical failure risks of photovoltaic power plants, the loss caused by connector damage or burnout ranks second.
Contact resistance vs power generation
In addition, we can also measure the impact of connectors on power generation from the perspective of contact resistance. The level of contact resistance means the amount of power loss. As mentioned earlier, the increase in module power reduces the amount of photovoltaic connectors, which means that the total contact resistance becomes smaller. However, with the increase in component current caused by the power increase, the overall loss of power generation has increased. Let's take Stäubli MC4-Evo2 and "Class MC4" as examples to take a look at this change, as shown below.
○When the module power is 300Wp
Installed capacity: 1MW
The number of full-time sending hours: 1500h
1MW connector consumption: 3500 sets
○When the module power is 400Wp
Installed capacity: 1MW
The number of full-time sending hours: 1500h
1MW connector consumption: 2592 sets
Of course, it can be seen from the above table that the use of high-quality photovoltaic connectors can significantly reduce the loss of power generation. In the era of high-power components, in the first year of operation of a 1MW power station, Stäubli MC4-Evo2 can generate 1202kWh (with less loss) of electricity for the owner, which is equivalent to an increase in system efficiency by 0.8‰; theoretically, a typical 50MW power station During the 25-year operation period, the Stäubli MC4-Evo2 can generate approximately 1.5 million kWh of excess electricity for the owner. At the same time, it should be pointed out that the contact resistance of the photovoltaic connector must be low and stable for a long time. The continuously increasing contact resistance will greatly increase the safety risk of the power station, reduce its operating efficiency, and increase the subsequent operation and maintenance costs.
In summary, the power of components is getting higher and higher, and the impact on components is mainly reflected in current and consumption. Stäubli photovoltaic connectors can fully meet the current demand of current components, while reducing losses and bringing more benefits to power station owners.
Since 1996, Stäubli’s attention to detail has made us trusted by customers in the photovoltaic industry, becoming its reliable product supplier and a competent partner in obtaining financing. Therefore, the customer maintains the efficient and safe operation of the photovoltaic power station. Choosing Stäubli, you will benefit from our professional experience, extensive technical support and high-quality products and services, and then achieve low electricity costs. Up to now, Stäubli photovoltaic connectors have successfully connected more than 280GW photovoltaic systems.