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Performance, Costs, and GHG Emissions of PV-Hybrid Systems: Current Status and Avenues for Improvement

Michael M.D. Ross
RER Renewable Energy Research

Full Text Article
Link to SESCI (conference)


Ross, Michael M. D. "Performance, Costs, and GHG Emissions of PV-Hybrid Systems: Current Status and Avenues for Improvement". Proceedings of the 32nd Annual Conference of the Solar Energy Society of Canada, Calgary, Alberta, June 10 to 13, 2007.


The performance of a photovoltaic hybrid system (consisting of a photovoltaic array, batteries, fossil-fuel combusting engine, synchronous generator, rectifier and inverter) is affected by a number of design choices and control parameters, and is, therefore, subject to optimization. At the outset of such an optimization exercise, it is useful to benchmark the performance of an unoptimized baseline system, i.e., one built according to current standard practice. The relative merits of proposed improvements can then be established by comparison with this benchmark.

This study uses simulation to determine the performance of a baseline PV hybrid system providing power to a 300 W moderately remote off-grid industrial load; it assumes climate and costs typical for Canada. It is compared with three competing alternatives—a prime power system, a genset-battery system, and a photovoltaic-battery system—on the basis of initial and annual costs, embodied energy, and greenhouse gas emissions. This comparison is repeated assuming a less remote, residential system with less expensive fuel and components, and then the impacts of various avenues for system improvement are examined.

Prime power systems are inappropriate for loads of this size, and this is reflected in high annual costs and emissions. But even the genset battery, PV and PV hybrid systems are expensive: the cost of electricity for the remote industrial application ranges from $2.40 to $3.67 per kWh. The PV hybrid system provides electricity the most cheaply, the genset-battery system has the lowest initial costs (ignoring the prime power system), and PV-battery system has the lowest greenhouse gas emissions. Its emissions are one-third those of the hybrid system, which are in turn one-third those of the genset-battery system.

Various potential improvements in hybrid system design and control are explored. These would incrementally reduce the cost of electricity, and might lower GHG emissions by over 50%.