# Calculate Size of Solar Panel

Calculate Size of Solar Panel, No of Solar Panel and Size of Inverter for following Electrical Load

• 1 No’s of 100W Computer use for 8 Hours/Day
• 2 No’s of 60W Fan use for 8 Hours/Day
• 1 No’s of 100W CFL Light use for 8 Hours/Day

Solar System Detail:

• Solar System Voltage (As per Battery Bank) = 48V DC
• Loose Wiring Connection Factor = 20%
• Daily Sunshine Hour in Summer = 6 Hours/Day
• Daily Sunshine Hour in Winter = 4.5 Hours/Day
• Daily Sunshine Hour in Monsoon = 4 Hours/Day

Inverter Detail:

• Future Load Expansion Factor = 10%
• Inverter Efficiency = 80%
• Inverter Power Factor =0.8

### Calculation:

Step-1: Calculate Electrical Usages per Day

• Power Consumption for Computer = No x Watt x Use Hours/Day
• Power Consumption for Computer = 1x100x8 =800 Watt Hr/Day
• Power Consumption for Fan = No x Watt x Use Hours/Day
• Power Consumption for Fan = 2x60x8 = 960 Watt Hr/Day
• Power Consumption for CFL Light = No x Watt x Use Hours/Day
• Power Consumption for CFL Light = 1x100x8 = 800 Watt Hr/Day
• Total Electrical Load = 800+960+800 =2560 Watt Hr/Day

Step-2: Calculate Solar Panel Size

• Average Sunshine Hours = Daily Sunshine Hour in Summer+ Winter+ Monsoon /3
• Average Sunshine Hours = 6+4.5+4 / 3 =8 Hours
• Total Electrical Load =2560 Watt Hr/Day
• Required Size of Solar Panel = (Electrical Load / Avg. Sunshine) X Correction Factor
• Required Size of Solar Panel =(2560 / 4.8) x 1.2 = 635.6 Watt
• Required Size of Solar Panel = 635.6 Watt

Step-3: Calculate No of Solar Panel / Array of Solar Panel

If we Use 250 Watt, 24V Solar Panel in Series-Parallel Type Connection

• In Series-Parallel Connection Both Capacity (watt) and Volt are increases
• No of String of Solar Panel (Watt) = Size of Solar Panel / Capacity of Each Panel
• No of String of Solar Panel ( Watt) = 635.6 / 250 = 2.5 No’s Say 3 No’s
• No of Solar Panel in Each String= Solar System Volt / Each Solar Panel Volt
• No of Solar Panel in Each String= 48/24 =2 No’s
• Total No of Solar Panel = No of String of Solar Panel x No of Solar Panel in Each String
• Total No of Solar Panel = 3×2 =6 No’s
• Total No of Solar Panel =6 No’s

Step-4: Calculate Electrical Load:

• Load for Computer = No x Watt
• Load for Computer = 1×100 =100 Watt
• Load for Fan = No x Watt
• Load for Fan = 2×60 = 120 Watt
• Load for CFL Light = No x Watt
• Load for CFL Light = 1×100 = 100 Watt
• Total Electrical Load = 100+120+100 =320 Watt

Step-5: Calculate Size of Inverter:

• Total Electrical Load in Watt = 320 Watt
• Total Electrical Load in VA= Watt /P.F
• Total Electrical Load in VA =320/0.8 = 400VA
• Size of Inverter =Total Load x Correction Factor / Efficiency
• Size of Inverter = 320 x 1.2 / 80% =440 Watt
• Size of Inverter =400 x 1.2 / 80% =600 VA
• Size of Inverter = 440 Watt or 600 VA

### Summary:

• Required Size of Solar Panel = 635.6 Watt
• Size of Each Solar Panel = 250 Watt. 12 V
• No of String of Solar Panel = 3 No’s
• No of Solar Panel in Each String = 2 No’s
• Total No of Solar Panel =6 No’s
• Total Size of Solar Panel = 750 Watt
• Size of Inverter = 440 watt or 600 VA

Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University. He has more than 14 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for "Electrical Mirror" and "Electrical India" Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

### 21 Responses to Calculate Size of Solar Panel

1. Atta Khan says:

Seen Thanks

2. Sharad Dubey says:

Dear Sir Total Size of Solar Panel – 250*6=1500 watt

3. Sharad Dubey says:

Sir,Total Size of Solar Panel-250*6 = 1500 watt

4. nvmani2006 says:

Explained in step by step.Nice.

5. Zaw Mayng says:

Thanka a lot.

6. kairu says:

thanks for the info,keep it up

7. Prakash s says:

Dear Sir,

We need how to calculate inverter size calculation please send to me.

8. Alam says:

Brother give me suggestions my main income supply is domestic 3 phase but my all side nutral between earthing voltage 35.what’s solutions

9. Kunal Prasad says:

Thanks

10. Yasir Bashir says:

ThanksPlease send more articles

Sent from Yahoo Mail on Android

11. Robert Oboth says:

Oh thanks, but my question is,what determines the charge of solar battery?. Is it the capacity of the battery, size of the panel or and the amount of sunshine?

12. Asif says:

I am having some doubt please clear it.
What is correction factor and why we are taking it as 1.2?

13. PREMJITH MP says:

Thanks for your article. but the average sunshine per day is coming only 4.8hrs?

14. Abdul Muhd says:

Hi Parmar…

Nice article as usual.

1. Please how can I effectively calculate the hour required for solar panels to fully charge let say 8 no battery bank

2. How can I calculate the solar panel array needed to charge a battery bank Example: Someone says I have 8 batteries, 12v 100Ah, whats the size of solar panel to fully charge my batteirs

15. manin says:

dear sir,
which factor depending for solar power system with battery & inverter..i cant understand how to calculate it?

16. Hafiz Sajid Abid says:

AOA!
Nice artical as usual.
but how i will calculate the required number of batteries and time for battery charging.

17. Ambuj says:

Assuming Solar System Voltage (As per Battery Bank) = 48V DC
Hence for determining ‘No of Solar Panel in Each String we divide ‘ Solar System Volt’ by ‘Each Solar Panel Volt’ ie…Solar System Volt / Each Solar Panel Volt<< I think this is applicable to Off Grid Battery Enabled system..

Now if its a On-Grid System with No battery Bank, than what should be appropiate value for system Voltage (230v or ??) so that we could determine 'No of Solar Panel in Each String ' ??

18. Anurag Bararia says:

How the total size of solar panel becomes 750 w when there are only two nos 0f 250 w are connected in series in each string.Moreover I also want to know how we measure the efficiency of the solar panel that is whether it generating the reqd. power.

19. bhas karan says:

In Step-2: Calculate Solar Panel Size

Average Sunshine Hours = 6+4.5+4 / 3 = 8 Hours, how it became 8 hours. i think it might be 4.8 Hours