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Operating Temperature Development of Overcommitted Inverters
U. Muntwyler, M. Bolliger, M. Lanz, T. Schott
Grid-Connected, Performance, PV Array, Inverter, Grid Integration
Photovoltaic Modules and BoS Components
Subtopic: Inverters and Balance of System Components
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4AV.2.37
1217 - 1219
ISBN: 3-936338-60-4
Paper DOI: 10.4229/EUPVSEC20192019-4AV.2.37
0,00 EUR
Document(s): paper


PV plants in Central Europe reach about 1,000 full load hours. So, they produce 1'000kWh / kWp. If a high expansion of PV power is sought, often an additional network expansion is necessary to absorb short-term power peaks. The grid expansion costs contrast with the peak output, which takes only a few hours each year. At the Technology Center of BKW Energie AG, this led to the idea of expanding the DC power more strongly than the AC side (for example, by parallel string assignment) and thereby increasing the amount of electricity per installed grid capacity. As a result, more solar energy is produced in the marginal times, while the midday peaks are flatter. To expand the DC side more than the AC side, the inverters must adjust the power. In order to keep the costs low and to increase security, commercially available inverters should be used. They are, with some exceptions, not designed for a PV array that has much more power than the peak power of the inverter. To learn the behavior of the devices, several inverters were offered up to 200% of the specified DC power (increased DC current) and simultaneously recorded the inverters MPP tracking and development of the operating temperature. The result of the investigation is that all tested inverters coped with the power surplus. They regulated the DC current by shifting the MPP and thus the operating temperature did not increase any further. The only limitations are the warranty of the equipment manufacturer if the inverters are operated outside the specifications. In addition, the specified system voltage must not be exceeded, otherwise the device will be damaged.