A1 Journal article (refereed), original research

Optimal dimensioning of a solar PV plant with measured electrical load curves in Finland

Open Access publication

Publication Details
Authors: Simola Aleksi, Kosonen Antti, Ahonen Tero, Ahola Jero, Korhonen Miika, Hannula Toni
Publisher: Elsevier
Publication year: 2018
Language: English
Related Journal or Series Information: Solar Energy
Volume number: 170
Start page: 113
End page: 123
Number of pages: 11
ISSN: 0038-092X
JUFO-Level of this publication: 2
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2018062626456


The amount of installed solar power
in Finland tripled in 2016, reaching 27 MWp. In Finland there are no
feed-in tariffs, and with the low price of electricity together with the
annual distribution of insolation concentrating on summer, the
photovoltaic electricity production is economical only when used for
self-consumption. When the produced electricity is used for
self-consumption, optimization of the photovoltaic power system size is
essential for the profitability of the investment. Usually when
optimizing the size of the PV system, the electricity production is
optimized so that the electricity sold to the grid is minimized.
However, this can lead to undersizing of the PV power system. The PV
power system size can for example be dimensioned by using methods such
as the minimum energy consumption of the building, the maximum power
consumption, or the net zero principle. In Finland, the smart meters
provide hourly consumption data from the electricity consumers, which
can be used to generate electrical load profiles. These smart meters
have been installed on almost every real estate.

In this paper, the profitability of a photovoltaic power system in the
conditions of southern Finland is studied, simulated, and analyzed for
self-consumption. Three cases, a grocery store, a dairy farm, and a
domestic house with direct electric space heating, are presented and
used in the simulation. Their electricity consumption is measured by
hourly automatic meter reading (AMR) on a yearly basis. An Excel tool
was used for the analysis of the electrical load profiles against the PV
power system production at different system sizes. The profitability of
the PV power system was studied by using internal interest rate, net
present value, discounted payback period, and self-consumption rate. The
effects of government subsidies on the profitability of a PV power
system were also examined.

The optimized system sizes for the grocery store, dairy farm, and
domestic house with direct electric space heating were 89 kWp, 28 kWp,
and 5.2 kWp, respectively. The solar modules of the grocery store and
the domestic house were facing south whereas the optimal module
orientation in the dairy farm was 50–50% east-west. It was found that in
the case of the grocery store and the dairy farm, the PV system size
could be increased without the internal rate of return decreasing
significantly, and thus, a larger system could be justified. Using the
self-consumption ratio to optimize the PV power system size leads to
undersizing of the system. It was found that the subsidies for the PV
power systems have a significant impact on profitability. In the cases
of optimized sizes, the grocery store would be economically viable even
if the electricity price decreased annually by 3.6% with subsidies and
1.0% without subsidies. The optimized PV power system of the dairy farm
would be economically viable if the electricity price decreased by 3.3%
annually; however, without subsidies the electricity price would have to
increase by 1.0% annually to remain viable. Considering a residential
house, the annual increase in electricity price should be 0.6% with
subsidies and 1.9% without subsidies.

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Last updated on 2019-13-03 at 12:00