- Carmine Arcudi
- Line Barras
- Didier Blatter
- Christoph Ellert
- Rodolfo Horta
- Pierre-Olivier Moix
- Dominique Roggo
- Florian Steiner
- Thomas Sterren
Based on the advantages of the DC-bus technology to link various producers and consumers the existing Photovoltaic test plant of the HES-SO Valais-Wallis, ISI, has been extended to a power of about 11 kWp installed PV-power and linked via the DC-bus power link at 700 Volt to a battery system (Lithium & Lead-Gel) and the in-house DC/AC converter. Again the high-efficiency individual DC/DC-converters for each PV-module have been built based on the in-house design via an external supplier, installed and tested. The wireless communication of the relevant PV-data (current, Voltage, temperature, panel-ID) is as well entirely developed inhouse, based on low power bluetooth.
Due to the permanent transmission of the relevant PV-data an online supervision of the produced power in realtime under real operating conditions with a time resolution of 10 seconds has been established. An evaluation of the performance of individual modules is thus possible, and has therefore been adapted at the PV-Lab in Neuchâtel as well.
The extensed DC-bus linked PV-plant of more than 10 kW consists of 30 crystalline PV-modules and 15 thin film micromorph modules. The upgrade with a local battery storage system on the DC-side of the DC/AC converter allows direct local energy storage and thus smoothening of the PV-production profile according to parameters which can freely be choosen.
The entire operational system forms the basis to be extended to a fully operational DC-microgrid, with many additional beneficial features like production and injection forecast, smoothening of power profile, guaranteeing a precisely defined power profile, integrating all kinds of consumers directly into the DC-bus (for example variable frequency motor drives), providing regulation power to GRD’s, etc.
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In order to integrate the battery (either Li or Pb) a precharing unit is required which guarantees perturbation free connection of the battery system.
Typical shape of the power profile of two micormorph silicon and five crystalline silicon PV-modules. The clearly distinct power curves proof that each module is individually optimized in power.