Back passivation series: The common feature of the three types of back passivation (PERC/PERL/PERT) structures is that a passivation layer is added on the basis of the traditional aluminum back field to better prevent electrons from recombining on the back surface. PERL and PERT are enhanced versions of PERC, because after the passivation layer is added, the material with the same polarity as the silicon chip is heavily diffused (partially or completely), forming another back electric field.
Heterojunction: Both crystalline and amorphous grades of silicon exist in the cell; the presence of amorphous silicon enables better passivation.
Back electrode: Place the positive and negative electrodes on the back of the battery, so there is no shadow loss caused by the front electrode part (silver paste) reflecting part of the incident light.
In theory, the definitions in Table 1 and Table 2 are based on different standards, and various combinations are possible. However, in the actual production process, some battery structures correspond to high production costs, and better silicon wafers are needed to make more efficient cells. Batteries are used to support its economy, so there are only the following combinations in commercial products:
Aluminum back field: single crystal (p-type), polycrystalline (p-type). The batteries of most manufacturers are of aluminum back field structure.
Back passivation series:
PERC: single crystal (p-type), polycrystalline (p-type). Such as TRW’s HoneyPlus, Hanwha’s Q.ANTUM, and Suntech’s HyPro.
PERL: single crystal (p-type). Such as JA Solar’s Percium.
PERT: single crystal (n-type). For example Yingli’s Panda, HT-SAAE’s MilkyWay, and LG’s MonoXNeON.
Heterojunction: Single crystal (n-type). Such as Panasonic’s products.
Back electrode: single crystal (n-type). Such as SunPower’s products.
In order of efficiency from high to low: back electrode, heterojunction, PERT, PERL, single crystal PERC, single crystal aluminum back field, polycrystalline PERC, polycrystalline aluminum back field.