The Gwaii Haanas PV Hybrid System: Analysis of System Operation

Michael M.D. Ross
GPCo Inc.

Note on Authorship:

This technical report was authored by the principal of RER Renewable Energy Research when he was an employee of GPCo Inc.

Acknowledgements:

Research conducted on behalf of the Photovoltaics and Hybrid Systems Program at the CETC-Varennes (Natural Resources Canada) with partial funding from the Panel on Energy Research and Development (PERD).

Citation:

Ross, Michael M. D. The Gwaii Haanas PV Hybrid System: Analysis of System Operation. Report to CETC-Varennes (Natural Resources Canada). Varennes, Québec, 2002.

Summary:

As part of the CANMET Energy Technology Center—Varennes Photovoltaic Hybrid Power System Program, the operation of the photovoltaic/battery/genset hybrid power system at the Gwaii Haanas National Park Reserve warden station has been monitored since July 2001. This monitored data has proven very useful for validation of hybrid system simulation tools being developed within the Program. In turn, these simulation tools, in combination with analysis of the data, have provided insight into the operation of the Gwaii Haanas power system, and helped identify the strengths and weaknesses of the system.

In general, the Gwaii Haanas power system seems to be functioning well. The system components appear to be appropriately dimensioned and configured. The arrangement of the modules in two sub-arrays, with modules connected in parallel, is remarkably tolerant of shading of part of the array, which must occur quite often given the proximity to the coniferous forest. Nevertheless, there are some ways that the system performance could be improved, and these would likely lead to longer battery lifetime.

During the winter, when the Park residence is not occupied, the batteries are very deeply discharged. This deep discharge appears to be caused principally by the idle power of the inverter. This suggests that a very small load—perhaps the clock on a VCR or a microwave—is keeping the inverter circuits energized, which in itself consumes about 12 W. This deep discharge may cause premature ageing of the batteries.

Considerable photovoltaic power is being rejected during the summer. During times of strong sunshine and low loads, users should feel free to use more energy. But these users should be very careful not to increase loads during periods of little sunshine that already have significant loads. During these periods, the battery may be deeply discharged, possibly causing premature battery aging. Users can keep track of the battery state-of-charge by staying aware of the status LED on the charge controller: when, during sunny hours, this is green and on continuously, the battery is near a full state-of-charge. If this indicator is found to be insufficient, the installation of an amp-hour counting device may be helpful.

The charge control setpoints appear to be quite low, and may not permit the battery to be fully charged.

Created 2007/03/07   Updated 2007/03/07     ©2007 RER Renewable Energy Research