Solar System Sizing
Step 2 and 3: Collect Loads and Construct a Load Profile
Load profile for this example
is the derated power output of the PV module (W) is the total design daily energy (VAh)
is the oversupply coefficient (pu)
all factors (e.g. tilt angle, tracking, etc) have been captured ( is the efficiency of the PV sub-system (pu)
is a design contingency factor to capture the uncertainty in designing solar power ure solar irradiation is not deterministic. AS/NZS 4509.2 Table 1 recommends oversupply
is the combined efficiencies of the charge regulator / controller, hrough the cable between the PV array and the battery. This will depend on specific circumstances (for example, the PV array a large distance from the battery), though an efficiency of around 90%
solar power system will be designed for a telecommunications outpost located in the desert.
Step 1: Estimate Solar Irradiation at the Site
From site measurements, the solar irradiation at the site during the worst month at the optimal title angle is 4.05
Step 2 and 3: Collect Loads and Construct a Load Profile
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is a design contingency factor to capture the uncertainty in designing solar power ure solar irradiation is not deterministic. AS/NZS 4509.2 Table 1 recommends oversupply
is the combined efficiencies of the charge regulator / controller, hrough the cable between the PV array and the battery. This will depend on specific circumstances (for example, the PV array a large distance from the battery), though an efficiency of around 90%
solar power system will be designed for a telecommunications outpost located in the desert.
From site measurements, the solar irradiation at the site during the worst month at the optimal title angle is 4.05
For this example, we shall use the same loads and load profile detailed in the
example. The load profile is shown in the figure right and the following quantities were calculated:
Design load Sd= 768 VA
Design energy demand E
Step 4: Battery Capacity Sizing
For this example, we shall use the same battery sizes calculated in the example. The selected number of cells in series is 62
Step 5: Estimate a Single PV Module's Output
A PV module with the following characteristics is chosen:
Peak module power,
Nominal voltage
Peak power temperature coefficient
Manufacturer's power output tolerance
Suppose the average daytime ambient temperature is 40C. The effective PV cell temperature is:
deg C
An MPPT controller will be used. The temperature derating factor is therefore:
Given a medium dirt derating factor of 0.97, the derated power output of the PV module is:
Step 6: Size the PV Array
Given an oversupply coefficient of 1.1 and a PV sub required for the PV array is:
For this example, we shall use the same loads and load profile detailed in the Energy Load Profile Calculation example. The load profile is shown in the figure right and the following quantities were calculated:
Ed= 3,216 VAh
Step 4: Battery Capacity Sizing
is example, we shall use the same battery sizes calculated in the Battery Sizing Calculation
example. The selected number of cells in series is 62 cells and the minimum battery capacity is 44.4 Ah.
Step 5: Estimate a Single PV Module's Output
A PV module with the following characteristics is chosen:
W-p Vdc
Peak power temperature coefficient % per deg C turer's power output tolerance %
Suppose the average daytime ambient temperature is 40C. The effective PV cell temperature is:
An MPPT controller will be used. The temperature derating factor is therefore:
of 0.97, the derated power output of the PV module is:
W
Given an oversupply coefficient of 1.1 and a PV sub-system efficiency of 85%, the number of PV modules
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example. The load profile is shown in the figure right and the following quantities were calculated:
Battery Sizing Calculation] worked cells and the minimum battery capacity is 44.4 Ah.
Suppose the average daytime ambient temperature is 40C. The effective PV cell temperature is:
of 0.97, the derated power output of the PV module is:
system efficiency of 85%, the number of PV modules
For this PV array, 12 modules are selected.
Standard Regulator
The number of PV modules required for the PV array can be found by using AS 3.4.3.11(1):
Where is the number of PV modules required
is the derated power output of the PV module (W) is the total design daily energy (VAh)
is the oversupply co-efficient (pu)
is the solar irradiation after all factors (e.g. tilt angle, tracking, etc) have been captured ( is the coulombic efficiency
The oversupply coefficient is a design contingency factor to capture the uncertainty in designing solar power systems where future solar irradiation is not deter
coefficients of between 1.3 and 2.0.
A battery coulombic efficiency of approximately 95% would be typically used.
10.9588 modules , 12 modules are selected.
The number of PV modules required for the PV array can be found by using AS\NZS 4509.2 equation
is the number of PV modules required
is the derated power output of the PV module (W) the total design daily energy (VAh)
efficient (pu)
is the solar irradiation after all factors (e.g. tilt angle, tracking, etc) have been captured ( coulombic efficiencyof the battery (pu)
is a design contingency factor to capture the uncertainty in designing solar power systems where future solar irradiation is not deterministic. AS/NZS 4509.2 Table 1 recommends oversupply
A battery coulombic efficiency of approximately 95% would be typically used.
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is the solar irradiation after all factors (e.g. tilt angle, tracking, etc) have been captured (kWh / m2/ day)
is a design contingency factor to capture the uncertainty in designing solar power ministic. AS/NZS 4509.2 Table 1 recommends oversupply
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Computer Software
It is recommended that the solar PV system sized in this calculation is simulated with computer software. For example, HOMERis a free software package for simulating and optimizing a distributed generation (DG) system originally developed by the National Renewable Energy Laboratory (NREL).
Screenshots from HOMER software
PV Output Battery Output
What Next?
With the sizing calculation completed, the solar PV equipment (PV array, batteries, charge controllers, etc) can be specified and a cost estimate or budget enquiry / requisition package issued. The approximate dimensions of the equipment (especially the PV array and batteries) can also be estimated and a design layout can be produced.
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