Current self-tracking photovoltaic modules

Abstract

The invention discloses a current self-tracking photovoltaic module, which includes a solar silicon wafer string Vc, an energy storage capacitor C, a controllable switch n, a freewheeling diode D, and an LCU logic control unit. The invention combines the energy storage capacitor C, the controllable switch n. The freewheeling diode D and the LCU logic control unit together form the CMU unit, and through reasonable setting of the connection of each electronic device, through periodic charge and discharge work, to complete the current mismatch of the solar silicon chip string Vc under special circumstances, The CMU unit can automatically track the main circuit current, so as to realize the current self-matching between components and realize the system MPPT function. Moreover, the solar silicon wafer string Vc of the present invention does not require molecular string protection, and is fully compatible with the existing centralized junction box assembly manufacturing process, while reducing the number of aluminum strip lines in the actual process and improving production efficiency.

Description

technical field [0001] The invention relates to a new type of photovoltaic module based on a photovoltaic cell intelligent management unit (CMU) for intelligent tracking and matching of photogenerated current between photovoltaic power generation modules, specifically a current self-tracking photovoltaic module. Background technique [0002] Crystalline silicon (monocrystalline and polycrystalline) photovoltaic power generation has been widely used. Based on PN junction photovoltaic power generation, the photovoltaic voltage of a single cell is only 0.55v-0.75v, so the standard module is multi-chip series connection. The current 60-piece 156mm*156mm (156.75mmx156.75mm±0.25mm) module is connected in series with 20 pieces as a string, and the three strings are connected in series to form a 60-piece series module; the current 72-piece module is also connected in series with 24 pieces. , and the three strings are connected in series to form 72 series modules. Bypass diodes are ...

AI Technical Summary

Problems solved by technology

[0003] Attached picture Figure 5 It belongs to the traditional photovoltaic module structure. With this traditional structure, when some cells in a string are blocked or stained or performance attenuation causes the photo-generated current to be smaller than the main circuit current and the bypass diode is turned on, the photo-generated current in the string will The cell with current mismatch will bear the reverse voltage bias superimposed on it by other cells in the string, see Image 6 .Taking the bias of a cell in a 20-cell string as an example, Vs+19Vc=-Vd, Vs=-(19Vc+Vd), depending on the degree of shading, the Vs value is around -12V, this reverse bias The set voltage causes the battery to leak in reverse and generate heat, forming a hot spot phenomenon. The thermal stress will cause the performance of the battery to decay and the effective life to be reduced; if this voltage causes the battery to break down in reverse, it will cause the battery to burn , causing a serious fire hazard

That is to say, with the traditional module structure, when the current mismatch of the strings is caused by factors such as shading, the shaded strings will not only fail to generate electricity, but will cause hot spots, which will cause different degrees of performance degradation in light cases, and cause fire hazards in severe cases.

[0004] At the same time, due to the limitation of the reverse withstand voltage value of the cells (the withstand voltage of single crystal 156 cells is generally tested by -12V / -50mA when the factory leaves the factory), the number of sub-string cells connected in series in traditional modules cannot be too large. (For example, 40 cells, the reverse voltage value of the shaded battery is -24V), too high reverse voltage will break down the PN junction of the shaded battery, make the battery permanently invalid, and cause a great fire hazard

At present, there is no intelligent management unit (CMU) design between photovoltaic cell strings, so that when the photo-generated current of the strings is mismatched, it will not enter the hot spot state, and the mismatched current will be stored and reintroduced into the main circuit to increase shading, etc. Current self-tracking photovoltaic modules of system power generation under factors

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