A1 Journal article (refereed), original research

Optimal sizing ratio of a solar PV inverter for minimizing the levelized cost of electricity in Finnish irradiation conditions

Open Access publication

Publication Details
Authors: Väisänen Jami, Kosonen Antti, Ahola Jero, Sallinen Timo, Hannula Toni
Publisher: Elsevier
Publication year: 2019
Language: English
Related Journal or Series Information: Solar Energy
Volume number: 185
Start page: 350
End page: 362
Number of pages: 13
ISSN: 0038-092X
eISSN: 1471-1257
JUFO-Level of this publication: 2
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2019050214022


The amount of installed solar power in
Finland is increasing as a result of decreasing photovoltaic (PV) system
component prices. The growth is especially noticeable in residential
systems, and ways to make PV electricity a more competitive choice for
Finnish residents are studied. One of these ways is to decrease the
solar PV electricity production costs by decreasing the investment costs
by undersizing the inverter of the PV system. The objective of
undersizing is to find the optimal array-to-inverter sizing ratio (AISR)
where the ratio of the economic loss from the clipped energy to the
economic gain from the decreased system investment achieved by an
undersized inverter is lowest.

In this paper, the
economically most optimal AISRs are determined for different residential
array sizes, orientations, and inclinations when operating in Finnish
locations and conditions. Calculations for each inverter size are
carried out by using recorded Finnish meteorological data and the
current Finnish PV system cost distribution, and by analyzing existing
1-s resolution production measurement data of a Finnish PV system. It is
concluded that it is necessary to use 1-s resolution data as the use of
1-h resolution production data would lead to more significant
undersizing caused by the power clipping occurring within an hour.

optimal AISRs presented in this study are higher than the optimal
ratios reported in previous studies for locations further south than
Finland. This can be explained by the northern location of Finland,
where the irradiance above Standard Test Conditions (STC) is lower than
in central Europe, for example. This allows more significant undersizing
as less energy is clipped even at higher ratios. In the case of
south-oriented arrays in a 30° installation angle, the optimal AISRs for
the 10 kW, 6 kW, and 3 kW inverters were 1.6, 1.8, and 2.08,
respectively. Again, the AISRs for the southwest-southeast facade
installations were 1.8, 1.9, and 2.17 for the inverters under study.
They do not clip the produced energy as much as rooftop systems because
their production is more evenly distributed throughout the day, yet they
do not achieve as low production costs either. It is pointed out that
if the PV self-consumption is optimized by using PV to heat water or
batteries as a storage, limitation of the PV generation might not be the
correct solution.

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Last updated on 2019-08-05 at 13:41