What is TMEIC's '3rd-Generation PV Inverter'? (2)

With advantages of both central-, string-type PV inverters

2019/08/24 19:01
Kenji Kaneko, Nikkei BP Intelligence Group, CleanTech Labo
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Continued from What is TMEIC's '3rd-Generation PV Inverter'? (1)

Can be carried by 2t truck

The advantages of the "modular system" are not limited to the above. Problems in construction and operation became prominent following the increase in the capacity of central-type PV inverters to mega-class levels. Trailers and heavy machinery are required for transportation and installation of the PV inverters due to the weight increase following the increase in the size. When one of the PV inverters stops operation during use, a wide range of solar panels are affected, increasing the power generation loss.

These problems were significantly decreased by incorporating the "modular system", according to TMEIC.

The module in the "Solar Ware U" was downsized to 2m in height, 1.1m in width and depth, and the weight is 1t or less. The installation area per capacity was reduced by 35% compared with conventional units (2.5MW) of TMEIC while the weight was reduced by 40%. Because of the light weight and compact size, the module can be transported easily by a 2t truck (Fig. 4).

Fig. 4: "Solar Ware U" (unit image) (source: TMEIC)

For weight reduction, materials were reviewed; resin covers were used instead of metal covers and aluminum frames were used instead of steel frames, in addition to incorporating the compact design.

The impact range of problems is minimized because failure of one module does not affect other modules when multi-connected PV inverter models are used. In the case where six units are connected and failure occurs in two of the units, for example, the remaining four remaining working units continue to generate power

Furthermore, MPPT (maximum power point tracking) for maximizing the output by controlling the power points (current value and voltage value) according to fluctuating sunlight, etc is performed by each module. So, the power generation amount could be higher compared with the case where the control is performed by a single large-capacity unit, when panels cannot be installed facing the same direction in mountains, for example.

When the output from some strings drops due to shading, MPPT is affected, and all PV inverters cannot be controlled to the optimum power points depending on the case. Such impact can be limited when MPPT is performed independently by each module.

This feature was said to be one of the advantages of string-type units. In this sense, the product is a central-type unit that features advantages of string-type units.