If you are planning to install solar panels on your roof to reduce your electricity bill and want to know how many solar panels are needed to power your house then you have to right place.
I am working in the solar industry for the last two years and have helped many families adopt solar to reduce their electricity bills and I would love to help you as well.
On an average a house with monthly electricity consumption of 1000 kWh requires 26 – 30 solar panels (Each solar panel is of 320 watt).
To calculate the number of solar panels to completely offset your home electricity bill you need to divide your house monthly average power consumption by 120, this should give you the total kilowatt of solar panels needed for your house.
Then to calculate the number of solar panels just divide the kilowatt obtained in the above calculation by the wattage of one solar panel which you are planning to use. (Nowadays average wattage of most solar panels is above 300 watts).
For example, If your home consumes 1000 kWh of electricity in a month, and you are planning to use 320 watt solar panels then your house solar requirement is 1000 kWh / 120 kWh = 8.3 kW of solar panels.
Since you are using 320 watt solar panels, the total number of solar panels needed to power your house will be 8,300 watt / 320 watt = 26 solar panels.
How Many Solar Panels Does My House Need?
To calculate the number of solar panels needed to power your house you need to know the following two things.
- Average monthly power consumption of your house.
- Average monthly solar power generation at your place.
To find the average monthly power consumption of your house, just look into your latest month’s electricity bill, there you will find your last 12 months’ power consumption. Add the last 12-month power consumption data and divide it by 12 to get your house’s average monthly power consumption.
Once your get your house’s average power consumption it’s time to know your average monthly solar power generation. The average monthly solar power generation varies from 80 kWh to 130 kWh.
I live in Mumbai, India here we get at least 4 – 5 sun hours every day for around 300 days in a year.
The average monthly power produced by a 1 kW solar system in Mumbai, India is around 110 kWh – 115 kWh. Let me clarify this value goes up in the summer and comes down in the rainy season so this is just an average value.
If your state or country receives a similar amount of sun hours throughout the year then you can assume your locality’s average monthly solar power generation to be 115 kWh.
Sun hours – A peak sun-hour, is an hour during which the intensity of sunlight is 1,000 watts per square meter. Peak sun hours is not same as ‘hours of sunlight’, you might get 6-8 hours of sunlight but your peak sun hours will be around 4.
In India sun hours varies from 3-5 hours, an average of 4 can be assumed for most places.
However, if you live in cold countries or places where there are less sun hours then don’t take this value just google your countries name with monthly solar power generation in the suffix and you will get a figure for your monthly solar power generation.
If you don’t want to do that too, then take the average monthly solar power generation in your area to be 100 kWh.
Now that you know your house monthly power consumption and average monthly solar power generation, let’s calculate the number of solar panels needed to power your house.
Calculate Number Of Solar Panels Needed To Power A House?
To calculate the number of solar panels needed to power your house use the following steps.
- Calculate your average monthly power consumption.
- Divide your average monthly power consumption by average monthly solar power generation (115 kWh if you live in India) to get your solar panels requirement in kilowatt.
- Divide your kilowatt solar requirement by the wattage of one solar panel (Take one solar panel wattage to be 330 Watt as this is the most common solar panel used in 2020).
Let’s say you live in Mumbai, India and you have calculated your house’s average monthly power consumption to be 900 kWh then how many solar panels will your house need? (assuming you use 220-watt solar panel) Let’s calculate.
- Your house average monthly power consumption = 900 kWh.
- Your average monthly solar power generation = 115 kWh.(Since you live in India).
- Divide average monthly power consumption by average monthly power generation to get kilowatt of solar panels, 900 kWh / 115 kWh = 7.82 kW of solar panels.
- To calculate the number of solar panels, divide the 7.82 kilowatt of solar panels by individual solar panels wattage which is 330 watt in our case, 7,800 watt / 330 watt = 23.63, approximately 24 solar panels.
Now use the below calculator to find out the number of solar panels needed to power your house.
If your state or country receives a similar amount of sun hours as India does then you can assume your average monthly solar power generation to be 110 kWh.
If you live in cold countries or places where there is fewer sun hours then don’t take this value just google your countries name with monthly solar power generation in the suffix and you will get a figure for your monthly solar power generation.
If you don’t want to do that too, then take the average monthly solar power generation in your area to be 100 kWh.
Factors Increasing Number Of Solar Panels For Your House:
Even the most expensive solar panel in the world will not work at its full potential if not installed correctly. The generation of solar panels depends on the following factors:
- Shadow: The biggest enemy of solar panels is the shadow on the panels. Objects near by the solar panels like buildings, trees, poles all cast shadows on the solar panels which hamper the generation. So the solar panels should be placed in such a place where it receives at least 5 – 6 hours of shadow free sunlight everyday.
- Orientation: Ideally solar panels should be oriented towards the equator. So if you live in countries which fall in northern hemisphere like USA, Canada, India then your solar panels should be facing the south and if you like in countries which fall in southern hemisphere like New Zealand then your solar panels should be facing the north.
- Angle of inclination: The angle of inclination from the ground also plays an important role in power generation since the position of sun changes during summer and winter. So an angle should be chosen such that you can get the best generation throughout the year. If you have enough money to throw on some fancy tech then you can opt for the tracker system which follows the sun path and gives the maximum generation.
- Dust & snow: Even the best solar panel in the world will fizz out if there is a thick layer of snow or dust on it. Dust and snow prevents the sun rays from hitting the solar cells, since no sun rays are hitting the panels no electricity will be produced.
If after doing shadow analysis you found that your solar panels will get shadow-free light only for 3 hours then you will have to oversize your solar system by adding an extra 1 kW of solar panels.
Conclusion On Calculating Solar Panels Requirement:
To calculate the number of solar panels needed for a home or a factory you need to first find out the average monthly consumption (kWh) of your house, then divide this by the average monthly solar power generation in your area. This should give you the kilowatt of solar panels needed to power your house, then just divide that by the wattage of individual solar panels to get the total number of solar panels needed for your home.
In India, the monthly power consumption of an average household is 250 kWh. Therefore an average Indian house needs approximately 2.3 kW of the solar system which is 7 solar panels each of 330 watts.
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