Step 3 Customer Energy Consumption

Assumption

SOLARMAN 200W PV module is used , Power tolerance +/-5%
Customer wishes PV module can cover 70% annual electricity consumption, 𝜀 = 70%.
Average peak sun hour per day, PSH = 5 hours
4% loss due to dirt
2.5% cable loss
97% inverter efficiency, ηinv= 0.97 (Obtain from inverter datasheet)
No shading
Average irradiance-weighted cell temperature from one year of weather data (°C), Tmod_ave = 53 °C

PV Module Datasheet

Concept

3.1 Monthly Energy Consumption For One Year

Collect one year energy consumption.

Example

3.2 Calculate Enorm

n: Total number of data collected (decimal)

Em: Energy consumption each month (kwh)

3.3 Calculate Eout

Edisplaced = Eout = Enorm X ε

ε Percentage of energy to be supplied using GCPV system (%)

Eout AC energy output from the GCPV system (kwh)

Edisplaced Energy displaced from the national grid (kWh)

Eout = 8583.27 * 70% = 6008.291 kWh

3.4 Calculate PSHi

PSHi = PSH X 365

PSHi = Total peak sun hour per annum (h)

PSH = Average peak sun hour per day (h)

If PSH not provided, may use this formula (refer to Step 3 Shading Profile >> Step 2.6 Calculate Average PSH):

PSHi = 5 X 365 = 1825 h

3.5 Calculate fmm

Take worst case.
Convert to decimal if need
- fmm = [ ( Pmax STC - Power tolerance(W) ) / Pmax STC] / 100%
- fmm = [ 100% - Power tolerance(%) ] / 100%

fmm = (100% - 5%) / 100 = 0.95

3.6 Calculate ftemp_ave

In this article Tmod_ave already assumed, for formula may refer to Step 4 Average Irradiance- Weighted Cell Temperature

ftemp_ave = 1 + [(-0.38) /100 x (53 - 25)] = 0.8936

3.7 Calculate fclean

fclean = (100 % - Dirt Loss %) /100

Dirt loss value is subjective in real life, around 3%-5%

fclean = (100% - 4% ) /100 =0.96

3.8 Calculate fdegrad

Power Degradation can be found from PV module datasheet from keywords below

Power Warranty from 0 to 1 years
Linear warranty from 0 to 1 years
Minimum power output from year 1

2. General Formula

Since we only compare 0 to 1 year, so can be simplify to:

fdegrad = 1 - ( 2% / 100 ) = 0.98

3.9 Calculate fshade

fshade = (100 % - Shading Loss %) /100

Shading loss may find through shading profile test in real life, refer to Step 3 Shading Profile .

fshade = 1 - ( 0% / 100 ) = 1.00

3.10 Calculate ηcable

ηcable = (100 % - Cable Loss %) /100

Refer to MS 1837:2018, the highest cable loss is 3%, so assume 100% - 3% = 97% (0.97) if not given

ηcable = (100 % - 2.5 %) /100 =0.975

3.11 Calculate Nt_ene

Minimum 22 units of PV modules can be installed to fullfill customer's electricty saving goal.

Reference

Design And Sizing of Grid-Connected Photovoltaic Power System - SEDA Malaysia- 4th Published 2023

Example 3.3

SEDA GCPV Tutorial Design - Nov 2024

1. Dimensioning of PV array - Question 5

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