Half-sheet technology has become a standard product for mainstream module companies because it brings a double improvement in module power and reliability and high maturity in mass production.
In practice, the module is affected by inter-cell differences, irradiation, shading, aging, etc., which may cause a current mismatch in the module. The emergence of double-sided cells further makes the current mismatch problem relatively more serious.
In fact, when the short-circuit current of a single cell change, the maximum power point of the module will move, not how much the short-circuit current of a single cell decreases, the power of the module will be lost accordingly.
The model considered is as follows: 72-cell (or 144-half-cell) module is irradiated with 1000W/m2, and the Isc of one cell (or half-cell) in the module becomes 95% of the normal value, and the rest of the cells are normal.
The electrical performance parameters of the normal and the abnormal whole cell with Isc reduced by 5% and half cell are as follows.
The effect of single-cell anomaly on the module power can be obtained by building the module circuit model in the simulation software and bringing in the cell electrical parameters (Figure below),
The results show that after a 5% drop in Isc and Imp of a single cell, Imp of the whole module drops by 0.325% and Imp of the half-cell module drops by 0.239%, and Vmp also increases slightly, making the power loss 0.136% and 0.073%, respectively. The mismatch loss of the half-sheet module is only about 1/2 of the whole module, which is due to the fact that the upper and lower parts of the current common half-sheet module version of the module are connected in parallel, and the change of the peak operating current of the lower part has no effect on the upper part.
Therefore, even if there are several cells in the lower half with short-circuit current reduced to 95% of the normal value, the power loss ratio of the half-sheet module will not change significantly, and the half-sheet module has obvious advantages over the whole module in terms of resistance to current mismatch.
The half-cell module has a significant advantage in an anti-current mismatch. When shaded, Hi-MO 3 has higher power generation than the whole module array. In addition, Hi-MO 3 products also have the advantage of lower hot spot temperature, bringing a new option for lower cost of electricity.
