Electrical Load Calculation and How to Set Up Solar System to Run a House

(Last Updated On: August 19, 2020)

Electrical load calculation

Electrical Load Calculation:

Electrical Load Calculation and How to Set Up Solar System to Run A house- Electrical Load calculation is very important because it determines how much money we are spending by using different types of appliances in a house. By using this information we can estimate to invest in a more energy-efficient appliance. To prevent high electric bills, we need to design systems that keep our homes as energy efficient as possible.

In this article, we will calculate the power of home appliances, and in the end we will set up a solar system to run a house. We will start with a 300 Watt solar system and will also do calculations for the 5000 watt solar system. So, before I explain the solar set up for a house, first I will perform electrical load calculation of different home appliances.

In last few years, energy efficiency and savings has become a main problem due to increase in energy prices the electricity unit price is increasing day by day, increase in energy consumption everyone want to live a comfortable life by using various types of appliances like ac, TV, geysers etc which are power consuming appliances, increase and concerns about the environmental changes due to global warming the climate is changing due which temperature is increasing so we need AC and DC fans in summer season . We have used real power consumption data. We have analyzed the power consumption data on the basis of daily consumption.

The load we consume in our homes are recorded in energy meter which is provided by the WAPDA(Pakistan’s Power Utility Company). There are two types of energy meters:

  • Disk meter
  • Digital energy meter

Digital energy meter

In digital we see that small red led blinks which show us the load. If the led blink fast it means that maximum appliance are switched on in the home. When the led blink slowly it means that load is minimum. When this led blink 3200 times it complete one unit. In some energy meter it complete unit when led blink 1000 times.

Disk energy meter

The disk energy meter consists of aluminium disk mounted on a spindle between two electro magnets. This disk rotated between these two electromagnets. In disk energy meter when the disk revolves 600 times it complete one unit.

Electrical Load Calculation of Home Appliances:


Ceiling fan is a commonly used in summer season. Ceiling fans consume more power than lighting, focus on fans to save electricity. Ceiling Fan Power Consumption is the power that it draws during the highest speed. The power consumption of a ceiling fan depends on the type and size of motor the ceiling fan usually uses induction motor ceiling fan. Energy efficient ceiling fans consume less power than an ordinary ceiling fan depend upon the winding of motor it consume current if cheap type of materials are used in winding of motor it will consume more power and produce heat. While calculating the overall house electrical load Fans should not be avoided.

Let us consider that we have 6 fans in our home and each fan is 120W. Now we will calculate the power of all fans:


So the total power of fans are 720 W.

For bill calculation we will calculate kilowatt hour to find that for how much duration each appliance running. Normally we use fans for 12 hours. We will use the formula

KWH= (watt×hour)/1000


LED bulbs are most important appliances in our home. It uses about 10 percent of energy. It has a power rating in terms of Watt-hour. It gives the power consumption per hour. For e.g. a 60W led bulb consumes 60W of electricity per hour. If this bulb is switched on for 10 hours, a 60W light bulb costs 600W and half unit of electricity is burned. All type of bulbs should be taken into consideration while performing the electrical load calculation.
Let us consider that we have 16 bulbs in our home and each bulb is 24W. Now we will calculate the power of all bulbs:
So the total power of bulbs are 384 W. We use bulbs for 8 hours.
KWH=3.072 kwh


Significant amount of energy is required for any heating or cooling appliance. An iron is household appliance uses pressure and heat for removing creases and wrinkles out of clothes and fabrics, when the current is given to iron the coil present in iron become hot and transfer heat to the base metal which is pressed against a fabric to straighten it. Modern clothing irons consist of water reservoir which sprinkles water during ironing. An iron has power consumption ranging between 800 to 2000 watts.
The power of iron is 1000W and we have considered one iron.
We use iron for 1 hour.
KWH=8 kwh


In today world ever body want entertainment. So they entertain themselves by using set-top boxes, televisions, and video game consoles, can use a significant portion of our homes energy. Television technology is improving day by day.
Ultra high-definition (HD)TVs have arrived, smart tech is fully integrated which consist of usb system, internet setting and many more option are presents in new models and televisions are slimmer and lighter each year. If we watch an average of five hours of TV a day and play video games for 6.3 hours a week, these devices can use about 55 kWh per month.
We have 2 TV in our home and each TV is 150W.
We use TV for 8 hours.
KWH=2.4 kwh


Refrigerators are a necessary household appliance in every home in summer season. Mostly Refrigerator in summer running 16 to 20 hours a day while in winter season it drive for 1 to 3 hours. Now day cooling system are advanced in refrigerator to perform multiple roles. Today, refrigerators are available in varied sizes, framework and performances. The fridge that we use in our homes has power consumption is ranging between 100 and 300 watts. Over a full day in summer season, a fridge is likely to use between 1 to 2 kilowatt-hours (kWh).
The Power of one refrigerator is 250W.
We use refrigerator for 10 hours.
KWH=2.5 kwh

Water Pump (Motor) :

A water pump is used to bring out water from the bottom of a well, up to a storage tank in home. Though the water pump does not run all the day continuously we run it when water is needed. To find the power consumption of a water pump we will first find the wattage of the motor then we will multiply it with the number of hours for which we will using it and divide by 1000. This will give the amount of kilowatt-hours of the water pump.
Motor normally we used in our home is 1hp.
1×746=746 W
We use water motor for 1 hour.
KWH=0.746 kwh


Power consumption of a geyser depends on volume and temperature of water it is mostly used in winter season; geysers generally maintain a temperature of 40-75 °C. There are two types of water geysers available i.e. instant type and storage type geysers. The instant geyser gives hot water immediately when we turn on the valve while the storage geyser takes time to boil water. Geysers are responsible for between 35% and 50% of your electricity bill in winter season. As another often-used appliance, your water heater comes in second at 14 percent of your home’s energy usage. An average water heater will run about 1 to3 hours a day and uses 4500 watts, adding up to 13.5 kWh per day, or 405 kWh per month.
Geyser power is 2000W.
We use geyser for 1 hour.
KWH=2 kwh

Washing machine:

Power consumption of washing machine comes from two major equipment’s one is heating equipment that provides hot water mix to the machine and second is electric motor that rotates the drum that cleans the clothes, other auxiliary electrical components like pumps, automatic valves and digital control panels consume only a fraction of energy.
Washing machine power is 200W.
We use washing machine for 2 hour.
KWH=0.4 kwh

Total KWH:
To calculate the total kwh we will add all the above values
Total KWH= 8.64+3.072+8+2.4+2.5+0.746+2+0.4
Total KWH = 27.758 unit
So we consume 27.758 units per day. Now to calculate bill for month we will multiply this value with 30.
30×27.758= 832.74 units

300 watt Solar System for home:
Now if we want to design 300 watt solar system for our home. The appliances that we can run on this system are:
2 Fans = 2×80= 160watt
2 Energy savers= 2×25= 50watt
1 tube light = 40watt
1 led tv = 50 watt
The overall load is 300W
Now to design this system we require:
Solar panels

Uninterruptable power supply (UPS):

Now for this system we will require about 500watt ups. We will use 800 or 1000 watt ups for better results.
Battery (AH):
Now to find which rating battery will be require for this system we will do the following calculations:
We will require 12V battery which will drive 300W load.
Battery will require 25A current. Now to calculate Battery size we will use the following formula
Battery size in AH =(Total load ×back up time)/(battery voltage)
Back up time means that for how much time we will drive this load for example we drive this load for 8 hours.
Battery size in AH = (w ×h)/v
Battery size in AH = (300 ×8)/12
Battery size in AH = 200 AH
Battery size will be increase or decrease depending upon the back-up time if we decrease the backup time the battery size will be decreased.

Battery charging current:

Now we will calculate how much current will be required to charge battery we will use the formula:
battery charging current= 1/10×battery rating

Electrical load calculation

Now in this case our battery rating is 200AH
battery charging current= 1/10×200
battery charging current= 20A
So 20A current will be required to charge the battery. Want to know more about the solar battery charger and its connections?

If you want to study more about Solar charge controllers and Batteries, read the following articles.

Best Solar charge controller wiring and Amazon Purchase link

Lead acid battery, Construction and, Working, and Charging

What is battery? Types of battery, Primary and Secondary cells

Solar Plates:

Now we will discuss how many solar plates will be requiring for this system. We will require such solar plates that will provide 20A current for charging battery and 25A current to drive the load.
Total current= 20+25= 45A
Solar plates Power = V× I
150W solar plate is use for 12V battery while 250W and 325W solar plates are used for 24V battery. The open voltage of 150W solar plate is 18 to 20 V. But when it is connected in circuit its voltage is about 14 to 16V.
Solar plates Power = 14× 45
Solar plates Power = 630W
To Calculate Number of solar plates we will use formula
Number of solar plates=(Total Power)/(solar plate power)
Number of solar plates=630/150
Number of solar plates=4.2
So we will require 4 plates to drive this system.

5 kilowatt Solar System for home:
We will drive the following appliances on this solar system
Fan = 6×120w =720W
Led bulb = 14×24w=336W
TV=1×150w =150W
Water pump = 1×746w=746 W
Washing machine=1×200w=200W
DC Inverter AC= 1.5 Ton= 1610W
Iron = 1×1000=1000W
Total Power =5012 watt
Now to design this system we required:
Solar panels
Uninterruptable power supply (UPS):
We can use inverex or homage 5.2KW inverter.
In this inverter built-in MPPT solar charger are present of 80A. It can withstand about:
Max pv=450vdc
Max Solar power =5000 watt

Solar Plates:

Now we will discuss how many solar plates will be requiring for this system. As we are designing 5Kwatt system
To Calculate Number of solar plates we will use formula
Number of solar plates=(Total Power)/(solar plate power)
We will use 250W solar panel
Number of solar plates=5000/250
Number of solar plates=20
So we will require 20 solar panels to drive this system.

This solar panel gives us:
Current= 8.5A
We will make two sets of solar panels which will contain 10 solar panels each. 10 solar panels will be connected in series and the other ten solar panels will also be connected in series as in series connection the voltage adds. So from one set will obtain:
Current =8.5 A
As the current in series remains the same.
The two set will be then connected in parallel as we know that current in parallel are added so the overall current will be
Total current = 8.5+8.5=17A
Battery (AH):
This system support 48V battery system. So to fulfill this condition we will use 4 batteries of 12V.
We will use a 230Ah battery. When the battery is full charge its voltage is about 14.5v. So the overall voltage of batteries are about:
Total back-up time:
As 1 battery rating are 230Ah
Power = 14.5× 230
Power = 3335watt/hr
We will connect these batteries in series as we have to create 48v setup. The total powers of all batteries are:
Total power=58 × 230
Total power =13340 watt/hr

Off-Grid Solar System:

Let us suppose that we have installed a 500W solar system in our home and the requirement of our home is 300W. The remaining 200W will be used to charge back up batteries. Now when the batteries will fully charge. Then the 200W power will be waste without using it because the batteries are charged. When the sunset then the inverter will get power from the batteries because solar panels did not work at night time. All the appliances of the home will be drive from the battery until it is fully discharged.

Electrical load calculation

On-Grid Solar System:

This system is similar to the off-grid system but in this system, we introduce the WAPDA line through the meter and the battery setup is not present in it. Now the advantage of the WAPDA line is that we can obtain power from WAPDA and also sell the extra power charged then we have 200W extra power which we can give to WAPDA this power can be monitored through a net meter which will show us that how much power we give to WAPDA and how much power we receive from WAPDA. The disadvantage of this system is that when the power supply is cut off we do not have any backup power as there is no battery setup in on-grid system.

Electrical load calculation

Hybrid Solar System:

The hybrid solar system is mix-up of on grid and off grid it can obtain power from solar, WAPDA(Power Utility Company) and also have back up system in form of batteries.

Electrical load calculation

So, that’s all about the electrical load calculation and how to set up a solar system to run a House. I hope you have learned something new from this article based on the Electrical load calculation. Any suggestions will be highly appreciated. Don’t forget to subscribe to my website and YouTube channel “Electronic Clinic”.

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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

1 Comment

  1. mashaa allah very nice explanation and very hard work you are doing sir thanks for such a nice info sharing keep it up we are supporting you

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