Proposed model architecture:
The proposed Solar-Wind-Diesel Hybrid generation system needs the
following components. A brief description is given below. A Block
Diagram of the proposed system is given in Fig. 1 .
Solar PV:
Solar PV is a semiconductor device that produces DC current when solar
irradiation is incident upon it. Solar cell is the basic unit of solar
system. It is a p-n junction basically. When light (photon) is incident
upon these cells electron is emitted from the p-n junction. The current
generated from the solar cell is called Photocurrent,
Iph. We do not use a single PV cell or module in
practical life. We use Solar PV array that is an interconnection of PV
modules. The equivalent circuit in ideal condition for a solar cell is
defined as a current source and diode connected in parallel. Load is
connected in parallel to solar cells. The relation between voltage and
current for a solar cell in ideal condition [24] can be represented
as:
(1)
Here,
IPV = Solar cell output current measured in
Ampere.Iph = Photocurrent measured in
Ampere.I0 = Diode current for Reverse saturation
measured in Ampere.q = Electron’s charge =1.6×10-19 C.k = Constant (Boltzman Const.) = 1.38×10-23J/K.T = Temperature of the cell measured in Kelvin.
As we know P = VI, the power output of the solar cell can be defined as
PPV =VPV * IPV(2)
Here,
PPV = Output power of the solar cell (W)VPV = Operating voltage of the Solar cell (V)IPV = Solar cell output current (A)
The electrical energy generation from a photovoltaic system can be
calculated from the following worldwide formulated equation [7] :
E= A × r × H × PR (3)
Where,
PR = Performance ratio, coefficient for losses (range between 0.5
and 0.9, preferred value = 0.75)E = Electrical Energy measured in kWh.A = Total area of solar module in m2.H = Annual std. global solar radiation on tilted panels.r = Solar module ratio (%)
In HOMER, for solar PV, it assumes that the output from PV module is
linearly proportional to the input irradiation. But in real life the
efficiency is not like that and is limited by several factors like
temperature, dust, various losses etc. Keeping these things in mind
HOMER has an input named ‘derating factor’ dedicated to compensate for
the variation in ideal and real life efficiencies. For this in our study
a derating factor of 80% is considered. The energy production by the
solar PV array can be formulated as [8],
(4)
Here,
f pv = Factor of derating.Ypv = Total capacity of solar PV array installed.It = Total solar radiation on the array in
kW/m2.Is = Incident radiation at std. test condition =
1 kW/m2.
In this study Generic flat plate PV is used. It has a rated capacity of
1 kW. Ground reflectance was considered 20%. Here we have considered 1
to 11 kW capacity solar PV modules for the system simulation. Some
relevant data regarding Solar PV is provided in Table 3 . Here
the costs considered in this work, lifetime for the solar PV considered
etc. are summarized. Fig.4 shows the cost curve which shows
graphically the relationship between the Quantity of PV modules and
Cost.
Table III: Solar PV parameters.