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How Many Solar Panels Are Needed To Run a House?

August 07, 2019

If you are following the current trends of the energy industry, you will know that we are slowly moving more towards solar energy sources. Even in your community, you must be witnessing a lot of your neighbours installing solar energy panels on the roof. The solar PV models are booming.

If you are thinking about saving money on electricity bills, solar energy is probably the right option for you.

But the first question which comes to mind is “How many solar panels do I need to run my house”?

The first step in determining how many solar panels you need involves first setting up your goals. You must first calculate your energy needs throughout the year. This can vary from

household to household and hence you cannot just borrow the calculations. You need to take some efforts to calculate it yourself.

But don’t worry I am here to help. This blog will help you identify your energy needs and calculate the number of solar panels you need to run your house.

To calculate the number of solar panels you need information like what is your yearly/monthly energy consumption? The amount of sunlight your area receives The Surface area of your roof, the wattage, and efficiency of the solar energy panels and the availability of net metering scheme.

One simple way of evaluating the needs of your solar panels is to consult a solar panel dealer or manufacturer, who can give your home energy evaluation.

How Much Solar Power Does Your House Need?

To find your monthly energy consumption, just look into your utility bills for the past 12 months (This way you will include both summer and winter season requirements). Look for the total number of units you consumed each month.

Sum up the total and take an average by dividing them by 12. The easiest way to calculate your sum total is to contact your electric utility and as for the details.

According to a study conducted in 2014, an average Indian household consumes about 90 units (kWh) of energy per month on an average. This electricity is enough to run two light bulbs, T.V. ceiling fans, refrigerator, and small kitchen appliances.

Obviously, your household could use more or less of the average amount depending on how big your house is, the number of family members, and the number of appliances you use.

How Many Hours of Sunlight Do You Need?

Geographically, India is an ideal location for solar panel installation. Different parts of India receives almost 300 days of unobstructed sunlight.

Residential electricity demands peaks during the evening hours since T.V. cooking and other cooling appliances are on.

The peak availability of sunlight will have a maximum effect on solar energy.

For example, if you live on the western side of the country, you could expect a maximum number of peak hours than the northeastern region. That doesn’t mean a homeowner in the eastern region cannot get solar, it’s only that you need more solar panels to produce the same amount of energy.

The cost of solar power has also decreased dramatically in the past two decades.  from $60 in the mid-seventies to $1 today. Given the current trend of coal prices, they are more likely to increase even in the coming years. Switching to solar energy sources is presently the best alternative.

The Effect of the Size of Solar Energy Panels

If you have a limited space to use, the number and size of solar panels play an important role. With a large usable roof, you could buy a less efficient system and compensate with more number of panels.

But if you have a small usable roof, buying less but efficient solar panels makes sense. It is the only way you could reach your desired output.

Typical solar energy panels today are about 65 by 39 inches, with some variation for each manufacturer. The size has been unchanged for a couple of decades, but the efficiency has increased dramatically from the past few years.

If you have answers for the above questions, choosing the number of solar panels would not be that difficult. A professional solar panel dealer would study your roof architecture and suggest the number of panels needed for your desired energy output.

Factors Affecting Solar Panel Efficiency

Solar Panel Type – Monocrystalline solar panels are made from the purest degree of silicon available. Hence these are the most efficient. Next is the polycrystalline panels, which is slightly less efficient than monocrystalline panels. New generation thin-film solar panels are the cheapest but less efficient panels and not suitable for household application.

Orientation – For best efficiency, the solar panel must be placed to receive the maximum amount of sunlight and generally preferred facing south in India. Solar trackers are invented to keep track of the movement of the sun but for a household application, they are just too expensive.

Temperature – Seems contradicting but too much sunlight could increase the resistance of solar panel and thus temperature. You need to ensure that solar panels are placed to get enough airflow to maintain optimum temperature.

Lifetime – It is believed that every 2 years, the solar panel loses 1% of its efficiency. Most solar panel manufacturers claim to retain 80% of its efficiency even after 25 years of usage.

Maintenance – Overall solar panels require very less maintenance. However, cleaning your solar panels every now and then is recommended. Just wiping off the dust and cleaning the panels with soapy water could do the job.


Typically most people want to be completely depended on solar energy panels for their energy needs. But with current efficiency, you need to partially be dependant on conventional electricity. The cost of a fully standalone solar panel is too expensive for a regular household.

You should also consider net metering when calculating the ROI of your solar panels. The whole premises of net metering is that you receive credit for the excess energy you produce.

Just taking all the above factors into consideration, you could realistically predict the number of solar panels required to run your house.


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