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elongs to the not very prosperous Donji Lapac County.
Prior to the last War in the region, the village comprised 65
households, now only seven are inhabited periodically.
Villagers come mostly during the summer time, in an effort
of restoring their property and repairing the demolished
houses. Many are planning on returning permanently if the
living conditions in the village would improve.
Only one house has been inhabited permanently for the
last three years. The house was rebuilt by the authorities.
The 220V AC installations in the house were provided with
renovation. It is a simple and small single-level building,
presently occupied by three persons. Their only occupation
has been agriculture and goats rising. Providing
refrigerating facilities, they would like to start cheese
production and diversification of other products. For all
these activities a supply of at least some electricity is
indispensable.
After a thorough analysis of first priority needs and daily
habits for such typical household, a power demand curves
were constructed, and presented in Fig.1.
kW
0.2
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
1 3 5 7 9 11 13 15 17 19 21 23
hours
Jan.(kW)
Feb.(kW)
Mar.(kW)
Apr.(kW)
May (kW)
June(kW)
July (kW)
Aug. (kW)
Sept.(kW)
Oct.(kW)
Nov.(kW)
Dec.kW)
Fig.1: Graphical presentation of the estimated first priority loads, given as
averaged monthly values in hourly time intervals.
First priority electricity load consists of several lightbulbs,
a freezer, a water-pump and some small appliance,
like cellular phone charger or similar. Expected electricity
load data were organized in a standardized way, as averaged
monthly values given in hourly time intervals.
IV. TECHNICAL ASPECTS
A. Solar radiation and climatic data
For any location the reliable knowledge of global (total)
solar irradiation is essential for the evaluation of solar
potential and for the prediction of the performance of any
solar-based device. In fact, values of both components of
global radiation on horizontal planes– direct component
(H_Bh) and diffuse component (H_Dh) need to be known,
since for real, inclined receiving plane (say, roof) the diffuse
component remains unchanged while the density of direct
component can be increased by proper inclination and
orientation. Generally, the long-term data (10-year average
or longer) are necessary, but the number of meteorological
stations in Croatia having such data is quite small. In this
work, we have used Meteonorm computer program whose
predictions of global radiation on horizontal planes at
locations far away from measuring station are very reliable
(to be presented elsewhere).
Monthly average of global radiation on horizontal
surfaces (GlobHor) in kWh/m 2 per month, for one of the
locations (Busevic), is shown in Fig. 2 as sum of Direct
component (H_Bh) and Diffuse component (H_Dh) of solar
radiation. Note that direct (beam) solar irradiation prevails
in summer and diffuse irradiation in winter months.
kWh/m2 month
220
200
180
160
140
120
100
80
60
40
20
0
Busevic
Inlands Location
H_Dh
H_Bh
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Months
Fig. 2 Basic solar data for a representative mountain location
B. Simulation of technical performance and economics of a
solar PV-based system
In this section, we present results of computer
simulations for a stand-alone PV system (consisting of PV
panels, battery, inverter, charge controller, etc) or for a PVgenset
hybrid system. Sizing of system components
depends, of course, on the expected load. Two loads (and
than two sizes of PV- systems) are analyzed. First priority
electricity load, labeled L1, consists of several light-bulbs
(11 W each), a freezer (150 W), a water-pump (75 W) and
some small appliance, like cell phone charger and radio,
totaling about 1.7- 1.9 kWh/day, or 677 kWh/year. Total
monthly load is about 60 kWh/month. Load estimates are
based on priorities from the interview with household
members, and on the assumed normal size higher quality
appliances (class A). If very energy efficient, but also more
expensive and not always readily available (class A+)
appliances would be used, L1 would be lower, or the same
L1 would include also some additional appliance (like TV),
but that will not affect seasonal variation of the load.
C. Basic PV-based solar system
The PV-produced power is still relatively expensive and
must not be wasted. Therefore, to minimize surpluses and
waste, the PV system was dimensioned to completely satisfy
basic electricity needs only when the solar supply is highest,
i.e. during summer months. That implicates that electricity
needs at other seasons will be covered only partly. We have
performed a number of simulations with different loads,
sizes and types of all elements of the PV system, and some
examples are shown here. In the first example, a basic PV
500 Wp system (Wp denotes peak-watt, which is defined as
the energy produced under standard conditions, i.e. 1000
W/m 2 of solar radiation at 25 o C) includes an array of high
efficiency (13.3%) monocrystalline silicon modules with
total surface area of 3.8 m 2 , and a set of batteries of total
capacity 400 Ah.
The analysis of seasonal variation has shown that L1 is
pretty constant throughout the year: while the expected
consumption of light-bulbs will be higher in winter months
(shorter days) the electricity consumption of a freezer will
be lower (smaller temperature difference between freezer set
temperature and air temperature in the surroundings,
especially if the freezer is placed (as expected and also
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