# Calculate Size of Solar Panel

January 8, 2016 22 Comments

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

**Electrical Load Detail:**

- 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 =1
**00 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**

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

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

Explained in step by step.Nice.

Thanka a lot.

thanks for the info,keep it up

Dear Sir,

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

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

Thanks

ThanksPlease send more articles

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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?

I am having some doubt please clear it.

What is correction factor and why we are taking it as 1.2?

Waiting for your reply.

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

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

dear sir,

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

AOA!

Nice artical as usual.

but how i will calculate the required number of batteries and time for battery charging.

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 ' ??

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.

thanks

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

Dear Jignesh,

I designed a system that has a load of 16W that runs for 12 hrs per night with a battery of 12V ,7AH using a single panel of 20W(TrueSun).Unfortunately the system works for 2 days then goes of completely.Could their be a problem with the design?