Fixed racking scenario, the wiring between PV modules is more common with upper and lower rows of C-type and one-type, and the wiring of neighbouring modules is generally hand-holding.
Flat single-axis 1P scenario, PV module series wiring, there are two wiring methods: hand-holding and jump wiring (also known as frog jump wiring).
hand-in-hand connection
In this technology, the installer will be adjacent to the PV module one after another continuously connected together, and then the two ends of the cable lead to the convergence box or string inverter, this wiring method is simple to operate, for the component itself junction box out of the cable length requirements are low, the current mainstream manufacturers of conventional components of the positive pole and the negative pole of the neighbouring components hand in hand connection, can meet the field wiring requirements.
The disadvantage of this single line wiring method is that in addition to the connection between the components, but also need to lead back from the end of the negative cable, and the positive cable together and then into the cable casing, the need for a longer extension of the photovoltaic cable, also known as the return line. If a longer return cable is pulled in incorrectly, it may result in a ground fault. As a result, the installer may need to do extra work to manage the cables to hold them in place.
jump wiring
By skipping every other PV module until the end of the array, and then return in turn, the wiring will eventually return to the same starting point, so there is no need to return to the line. However, for the component itself, the length of the junction box cable is required to be higher, the mainstream 1134 width version, generally need to be customised to reach a total length of 1.6m or more (specific need to consider the width of the component, the cable wiring margin).
In addition, the junction box out of the cable increase, the loss is also a corresponding increase in the need to make up for the power from the component, the circuit loss, per metre about the need to make up for the 0.9W-1W power.
Some peers believe that this technology is more effective than the hand-holding method in reducing voltage drop and reducing line losses. It is worth noting that, in the case of insufficient cable length (such as less than 1.10m), jumping is not feasible, it is also believed that the jumper connection method of construction personnel are easy to confuse mistakenly, in the actual project application is less.
Cable savings depend on the length of the string. Assuming that the size of the PV module is 2382mm * 1134mm, 1500V system voltage, the number of module strings is 27, the module transverse spacing 0.04m, longitudinal single-row installation, if the hand-holding connection method is adopted and the cross-section of PV cable used is 4mm2, an additional PV cable of about 31-32m is required to achieve the same-side outlet into the cable casing. If the jump connection method is used, it is equivalent to save about 31-32m.
For the current mainstream TOPCon module, 66C and 72C version of the current due to different, STC line loss decline has a little difference, 66 version of about 0.21%, 72 version of about 0.17%; according to the software simulation of the annual line loss rate difference will be even smaller. In terms of PV cable cost savings of about 0.6-0.8 ¢ / W (higher overseas labour cost scenarios).
On the 5 MW PV system, if the module cable customisation brought about by the cost per watt remains unchanged, only the jumper type cabling can reduce the cost of more than $20,000 USD. Integrators can further reduce this by combining jumper cabling with Y-connectors.
The above is only from the system point of view, but if the comprehensive consideration of components, system costs, component power is unchanged, if the 4 square component cable customised, from the conventional length to 1600mm or even longer to achieve the jumpers, 27 components need to increase the length of the cable is similar to the length of a return line. Therefore, the length of the component’s own cable is increasing, the length of the return line is decreasing, taking into account the cost of both, in fact, the jumper connection method is not necessarily cost-saving.
What do you think?