A new sizing approach for PV self-consumption without storage

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Researchers from Spain’s University of Jaen claim to have developed a method of evaluating the cost-competitiveness and profitability of PV systems for self-consumption without associated storage systems.

In the paper A new approach based on economic profitability to sizing the photovoltaic generator in self-consumption systems without storage, the researchers say their customer-driven investment method takes into account more factors than traditional approaches. The Spanish team says its method considers taxes, depreciation, the escalation rate of operation and maintenance of such systems and financing costs, in addition to the usual indices of net present value, self-sufficiency and self-consumption.

The techno-economic model is said to be based on maximizing economic profitability, with net present value (NPV) – the difference between the present value of cash inflows and the capital expenditure related to the project – the criterion used.

Net metering

The researchers considered two scenarios: One in which surplus electricity is injected to the grid in return for compensation under net metering; and another in which the surplus energy is wasted. In both scenarios, remuneration for self-consumed electricity was calculated according to retail market prices.

“The recording interval for load consumption and irradiance data is crucial when estimating determined economic parameters that are estimated through the self-consumed energy,” the research team wrote.

The scientists state there is only one maximum value for a given array’s power which provides the maximum economic profitability. “Generally, for each of the houses, higher NPV [is] achieved when time-of-use in the price of electricity is considered, instead of a flat rate,” they added.

The model was tested for 12 months on three southern Spanish households with rooftop PV from June 2016 to May 2017. “The method developed here may be easily replicated as it is widely detailed and may be applied in any country if the corresponding techno-economic parameters are considered,” the researchers stated.