How Many Solar Panels Do I Need?
You may want to install solar panels for your home so you can get rid of heavy electricity bills, but confused about how many panels i need to install for my home. You need to consider many elements while calculating the required number of solar panels. You can calculate the necessary solar panels for your home by calculating the total appliance load and estimating your annual, monthly, and daily energy consumption from your electricity bills. Major factors to consider while calculating the total number of required solar panels for your requirements are:
- Your house’s average energy requirements – Load Calculation
- Current energy usage in kilowatt-hours (kWh) – Electricity Bill
- Solar panel size and efficiency
- Sunlight and climate in your area
I will first tell you about the factors that affect the number of solar panels required, then I will tell you the methods to know and calculate of solar panels you need.
How Many Solar Panels Do I Need to Install For My Home?
People are looking to install solar panels to reduce their electricity bills and get rid of electricity interruptions from the grid. However, they are curious about how many solar panels they need to install for their home and what will be the total cost. Well, I will guide you to calculate the exact number of solar panels you need to install so the solar system can perfectly match your electricity needs. Two major ways to calculate the required number of solar panels. One is to calculate the appliances load and the other is through your electricity bill consumption.
Factors That Decide How Many Solar Panels You Will Need
Electricity Usage Of Your Home
An important factor in deciding the number of solar panels your house will need is to learn your home’s electricity consumption. Electricity usage is measured in units as kilowatt-hour (kWh). You can find how much your home currently uses from your monthly WAPDA electricity bill.
A household that uses 500 kWh per month with an average of 6 peak solar hours per day will need a larger solar system than a home that only uses 200 kWh in a month. The higher the energy consumption of your household, the larger the solar system your home needs means the installation of more solar panels.
A home with energy-efficient devices will need less number of solar panels as these need low electricity consumption. Energy-saving appliances such as LED lights, LED TVs, Inverter AC and other devices can reduce your electricity bill and also the solar panels requirement.
Solar Panel Size
Mechanical dimensions of solar panels matter for the installation of your home rooftop solar system. The normal range of solar panel size measures around 2 by 1 meter but it can vary depending on the brand and model. If your home has space or shadow concerns then solar panel size becomes much critical.
You need to choose more efficient and compact size solar panels in case your home has less rooftop space. Otherwise, you can choose cheap, big size and larger number of solar panels to generate the same amount of electricity for your home.
Solar Panel Wattage
There are several models of solar panels having different wattage and generating different electricity output. Such as some panels are 300 watts and some are 500 watts solar panels so the higher the wattage higher the output. Consider the panels wattage rating carefully while installing a solar system for your home. Solar panel wattage and specification should align with the inverter being installed. With the wattage of solar panels, the number of required solar panels will vary.
Budget
While selecting the number of solar panels for your house you should also keep an eye on your pocket. If your pocket allows, you can buy more number of solar panels for charging batteries or running all the load during low sunshine and without any worries. For example, if you have a budget for 3KW solar system you may want to purchase 6 solar panels of 550W instead of 5 solar panels.
Production Ratio
The solar system’s production ratio is measured as the estimated energy output to the actual capacity of the solar system installed. If 100W of solar panel is generating 100W electricity over the determining period of time, its ratio i 1. But actually due to many factors solar panels cannot generate their maximum power. There is not always perfect solar irradiance, dust, angle of the array, and temperature matter. In Pakistan depending upon the sunlight hours and climate solar systems are designed from 1.2 to 1.6 ratio.
Sunlight and Climate In Your Area
Sunlight hours affect the output of electricity from solar panels. So in areas with medium to high sunlight, there are an average of 6-8 sun peak hours, solar panels generate maximum electricity in these areas. Output is affected by the cloudy weather or dusty storm in your area.
Size of Your Home
Home size also matters in electricity consumption, so when choosing a solar system, your home size will also play a vital role. How many marla houses and rooms are there? A 3-marla house with 2-3 rooms will need only a 3KW system, with an average consumption of 400KWh.
How to Calculate the Number of Solar Panels Required to Power Your Home
Using Load Calculation
You should use the below formula after calculating your total appliance load. The appliance Load Calculator is a very useful tool when you are looking to calculate the number of solar panels required for your house.
Required Quantity of Panels = [Total Load in Watt x 1.3] / Panel Wattage.
For example, your total load calculated by the Appliance calculator is 2500 watts. Using below formula
Quantity of Solar Panels Required = [ 2500 W x 1.3 ] / 550 W =5.9 ~ 6
So after this calculation and example, you are clear that you need a total 6 number of solar panels for your house.
You can use the following table for calculating the total appliance load, the power wattage of each home appliance is given below.
| Appliance | Watts |
| Tube Light | 40 W |
| LED Bulbs | 7 W |
| Energy Savers | 25 W |
| Fans | 100 W |
| TVs | 250 W |
| LED TVs 32″ | 50 W |
| Washing Machines | 800 W |
| Freezers | 350 W |
| Refrigerators | 350 W |
| Computers | 250 W |
| Irons | 1000 W |
| Water Pumps 1HP | 700 W |
| Split ACs 1 Ton | 1800 W |
| Split ACs 1.5 Ton | 2400 W |
| Split ACs 2 Ton | 3000 W |
| Split ACs 3.5 Ton | 7500 W |
| Split ACs 4 Ton | 8000 W |
| Inverter ACs 1 Ton | 1000 W |
| Inverter ACs 1.5 Ton | 1500 W |
| Inverter ACs 2 Ton | 2000 W |
If you are a little lazy to do this calculation there are some other methods by which you can easily estimate the required number of solar panels for your house.
Observing Electricity Consumption From Bill
If doing mathematics is not a cup of cake for you, then there are other easy methods. See your monthly electricity bill for WAPDA. The below table shows the units of electricity consumed per month simply multiply the KW system required by 1000 to convert it into watts and then divide this by the solar panel wattage, this will give you the required number of solar panels.
| Monthly Units(kWh) | Typical Solar System Needed(kW) |
| 350 | 3 |
| 650 | 5 |
| 1400 | 10 |
| 2100 | 15 |
| 2950 | 20 |
| 3500 | 25 |
Solar System Required Based On Your Home Appliances
Different types and numbers of appliances in your house determines the solar system and the number of solar panels required for your home. Multiply the system (KW) by 1000 and then divide by the wattage of the solar panel you want to use for your solar system this will give you the required number of solar panels.
| AppliancesSystem | Fans | Lights | AC / Iron | Fridge | Water Pump / Washing Machine | LED TV |
| 5 KW | 5 | 10 | 1 / 1 | 1 | 0 / 1 | 1 |
| 10 KW | 10 | 15 | 2 / 1 | 1 | 1 / 1 | 2 |
| 15 KW | 20 | 30 | 3 / 1 | 2 | 1 / 1 | 3 |
| 20 Kw | 20 | 30 | 5 / 1 | 4 | 2 / 2 | 4 |
Capacity of your rooftop
You can also determine the solar system size by your house size. In below table here is the estimated required solar size given against the size of the house. Use the same formula multiply the system by 1000 and divide by the wattage rating of your solar panel.
| Square Footage | Possible System Installation |
| 500 – 700 | 5kW |
| 800 – 1100 | 8kW |
| 1200 – 1500 | 10kW |
| 1800 – 2000 | 15kW |
| 2300 – 2500 | 20kW |
| 3200 – 3500 | 30kW |
| 4700 – 5000 | 40kW |
Final Words
Solar panel installation is very smart financial investment for many house owners. Due to current heavy electricity rates and inflations it is very hard for average people to feed and live normal lives. Although initial cost of solar system is little higher but it is long term saving from electricity bills. Number of solar panels required can be calculated using load calculation, monthly electricity bill and home appliances. But for final solar system design, you must consult with a solar system expert.