How to design Solar System in Pakistan?

In recent age the electricity by utility companies is getting
expensive,especially in underdeveloped countries like Pakistan.so the peoples are shifting their houses and industries power system towards solar systems.many of my friends often asked me the queries about installing the solar system in their homes.So thats why i'm making this tutorial.If you will follow all the steps given below properly then at the end you will be able to design your own solar system for your home.  

What is solar PV system?

Solar photovoltaic system or Solar power system is one

of renewable energy system which uses PV modules to convert

sunlight into electricity
.The electricity generated can be either

stored or used directly, fed back into grid line or combined with one

or more other electricity generators or more renewable energy

source.

Solar PV system is very reliable and clean source of electricity that

can suit a wide range of applications such as residence, industry,

 agriculture, livestock, etc.

Major system components

Following are the components which you need for installing the

system.

      1-PV module – converts sunlight into DC electricity.

2-Solar charge controller – regulates the voltage and current coming from the PV panels going to battery and prevents battery overcharging and prolongs the battery life.

3-Inverter – converts DC output of PV panels into a clean AC current for AC appliances or fed back into grid line.

4-Battery – stores energy for supplying to electrical appliances when there is a demand.

5-Load – is electrical appliances that connected to solar PV system such as lights, radio, TV, computer, refrigerator, etc. 

6-Auxiliary energy sources - is diesel generator or other renewable energy sources.

Now we will discuss each component.We will discuss how can be

these components selected?What should be their ratings? etc...

Solar PV system sizing:

There are five points for sizing the system.

1-Determine power consumption demands

i)Calculate total Watt-hours per day for each appliance used.

ii)alculate total Watt-hours per day needed from the PV modules.

2)Size the PV modules

i)Calculate the total Watt-peak rating needed for PV modules

ii)Calculate the number of PV panels for the system

3-Inverter sizing

An inverter is used in the system where AC power output is

needed. The input rating of the inverter should never be lower than

the total watt of appliances. The inverter must have the same

nominal voltage as your battery.

For stand-alone systems, the inverter must be large enough to

handle the total amount of Watts you will be using at one time. The

inverter size should be 25-30% bigger than total Watts of

appliances. In case of appliance type is motor or compressor then

inverter size should be minimum 3 times the capacity of those

appliances and must be added to the inverter capacity to handle

surge current during starting.

For grid tie systems or grid connected systems, the input rating of

the inverter should be same as PV array rating to allow for safe and

efficient operation.

4-Battery sizing:

Calculate total Watt-hours per day used by appliances.

Divide the total Watt-hours per day used by 0.85 for battery loss.

Divide the answer obtained by 0.6 for depth of discharge.

Divide the answer obtained by the nominal battery voltage.

Multiply the answer obtained with days of autonomy (the number

of days that you need the system to operate when there is no powe

produced by PV panels) to get the required Ampere-hour capacity

of deep-cycle battery

Battery Capacity (Ah) =(total watt-hours per day used×days of autonomy)⁒(0.86×0.6×nominal battry voltage)

5)Solar charge controller sizing

Solar charge controller rating = Total short circuit current of PV

array x 1.3

Peak Panel Power = Panel Wh/day ¸ PGF

Power Generation Factor(PGF):

Power generation factor is a value which is used in calculating the

panel modules sizing. It varies according to climate conditions all

over the world, in Pakistan it also has different values with respect

to location areas. PGF values for Pakistan different areas are given

below:

Before going towards practical work please solve this example by yourself.

Example: A house has the following electrical appliance usage:

One 18 Watt fluorescent lamp with electronic ballast used 4 hours per day.

One 60 Watt fan used for 2 hours per day.

One 75 Watt refrigerator that runs 24 hours per day with compressor run 12 hours and

off 12 hours.

The system will be powered by 12 Vdc, 110 Wp PV modules.