This is another question that I get a lot, How many solar panels do I need for my home? In today’s post, I am going to show you how to calculate the number of solar panels you need for your home.
Decide what you do want to achieve with solar panels
Before you install solar panels on your house you need to decide what you want to achieve by installing solar panels.
Do you want to cut half of your electricity bill? do you want to depend 100% on solar energy? This is the decision you need to make before installing solar panels.
How to calculate how many solar panels do you need for your home?
I am going to share with you how you can calculate the number of solar panels needed for your house in two steps, the first step will be to calculate the energy you need and the second step will be to calculate the number of solar panels needed. To calculate solar power needs at our home, proceed as follows:
Step 1: How much power do you use per day?
You need to calculate how much energy you need to power your house, in this case, we have two scenarios, the first scenario is if you have been paying bills for the last year and the second scenario is if this is a brand new house.
If you have electricity bills
In this scenario, I am assuming you have been paying electricity bills for the last year and you have historical data for the past 12 months.
To calculate this, get the last one-year monthly power bill, add all kilowatt-hours for the whole year, then divide the number by 12, to get your average monthly usage.
Now take our average monthly usage and divide it by 30 to work out our average daily power consumption. As we get our electricity bills in units, we have to convert units into watts.
Suppose consumption of a house is 2400 units per year. Therefore, power usage is 2400/12=200 units per month.
Now to get the amount of kilowatt-hour per day you need to divide that number by 30, 200/30=6.7 kilowatt-hour. So the power consumption is 6.7 kilowatt-hours.
If you do not have electricity bills
If it is a brand new house, probably you do not have electricity bills to calculate your daily consumption average, in this case, you can do the following.
All electronics devices have the maximum power consumption label, most of the time it will be in watts, all you need to do is to find that number, let’s say 50 watts, multiply with the amount of time on average per day you wish to use that item.
For example, I use electric bulbs on average of 8 hours per day, so I will multiply by 8, then a device that number by 1000 to change it to Kwh.
For example, if I have 5 bulbs that consume 50w each and I am going to turn them on for 8 hours, the energy consumption will be 50*8/1000=0.4 Kwh per bulb, since there are 5 bulbs I will multiply this number by 5, that is 2 kWh per day.
Now perform the same calculation for all devices you plan to use, the television, the refrigerator, the laptop, etc, and then find the total energy consumption per day.
Step 2: Calculate the total number of solar panels needed
Before you can calculate the number of solar panels needed to cover your electricity needs, you need to find out how many usable hours of sunlight in your region each day.
The easiest way to do this is to look at an isolation map, if you are a professional solar panels installer you might have software that will help you with that but if you don’t you can just check on https://www.nrel.gov/gis/solar.html
Now, imagine that you live in a location where on average there are 8 hours of sunlight every day. and from the step above you have a total daily consumption of 6.7 kWh per day.
Now take the average consumption in kWh calculated in step 1, divide it by the number of daily usable sunlight and then multiply it by 1.25 ( this is to compensate for the power loss due to batteries, solar inverter, and wiring ).
If we continue with the example above, the solar panel watt needs equal: 6.7 kWh needed / 8hrs of
sunlight*1.25=1.046 kW or 1046 watts per day.
If you want 300 W solar panels, that is 1046/300 that is 3.5 solar panels which means you will need 4 solar panels.
If you will use 100W solar panels which are 10.5 panels, you will need 11 solar panels to power your house.
With 4 300W solar panels, you will be able to produce 1200 Watts per day and with 11 100 W solar panels you will be able to produce 1100 watts per day, whichever type of solar panels you choose you should be able to power your house without a problem.
That is it, this is how you can calculate the number of solar panels needed to power your house, thank you for reading.