How many solar panels do you need?: A 2020 Guide

How many solar panels do I need?

While determining how many solar panels do you need, you should first look for your electricity needs.  

Most people want to generate enough energy to eliminate their electricity bills while others just want to cover their partial usage.

It is always best to keep your electricity consumption in mind before installing PV panels.

No need to worry if you do not know it!

People are often confused while deciding the number of PV panels they should install either it is for home or utility purposes.

In this blog post, I will cover all the factors that you should not forget to consider before adopting solar power. 

I will guide you with the stepwise approach, so that, at the end of this post, you will get the exact number of solar panels you will need to install.

I think the future of solar energy is bright🔆…Make the sun work for you! Click To Tweet

Let’s start with the factors you should look over before the installation of panels-

What factors decide your panel requirement?

✔️The amount of energy consumption.

✔️Your geographical location.

✔️The direction of the roof.

✔️Best angles and directions for your solar panel.

✔️ The amount of wattage or energy the solar panel you purchase can produce.

Considering the above factors will conclude your total panel count.

So, without further delay, Let’s move forward to know how to analyze these factors?

Know your Energy Consumption

To find your energy consumption, let’s follow the following steps:

#1 Get Your past Utility Bills 

To know what amount of electricity will you need, first, get your past electricity bills.

Your electricity bills should be the most recent, that is, the last 6 to 12 months bills.

#2 Look for your Monthly Usage

Once you get your bills, collect your usage from each bill. Note this number down for each bill you have.

It is typically shown in the kWh or kiloWatt-Hours.

**If your bill doesn’t show kWh usage, then subtract ending meter readings to the previous one.

#3 Calculate your daily kWh usage

Now, take an average of all those numbers and calculate the average daily electricity consumption.

Let say you have your past 6 months bill and the usage for the same is 300 kWh, 200 kWh, 275 kWh, 125 kWh, 250 kWh, 350 kWh respectively.

Then, the average monthly electricity consumption is

=(300+200+275+125+250+350)/6

=9000/6 

=1500 kWh

Likewise, the average daily electricity consumption is

=(average monthly consumption/30)

=1500/30

=50 kWh

Now, you got the values of how much daily electricity you will need.

How much wattage should your system produce?

The average daily usage you got is your full day usage, that is day and night. But, you only get the sunlight during the day time.

To deal with this you need a battery backup system so that you can store solar energy for later use.

For this, you can have an off-grid system or a hybrid system.

But, you have to spend extra for battery backup.

Thanks to Net Metering! By doing your house or firm net-metered, you do not need to spend money on the battery backup.

If you are installing a battery backup, your system should be able to produce enough energy that you will be able to use at night time.

So, how to get the energy production that your panel needs to produce every hour?

It depends on the peak sunlight hours you are getting in your area.

How many hours of sunlight can you expect at your location?

Peak Sunlight hours describes the intensity of sunlight in a specific area.

Generally, panels get 7 hours of sunlight. But, the intensity of the sunlight is highest for 4-5 hours only.

These hours are the peak hours for your panels to absorb the maximum solar energy.

Below is the peak sun hours map by UnboundSolar, indicating the average solar insolation (full sun hours) for these zones.

Peak Sunlight hours-Map
Peak Sunlight hours-Map

Suppose, you have 4 peak hours of sunlight at your location.

Multiply the average hourly kWh requirement by the number of peak sunlight hours.

Then, 

Average hourly wattage your system should produce 

= Hourly energy requirement × Peak sunlight hours

= (50 kWh /24 hours) × 4 hours

= 8 kW (approximately)

or 8000 Watts

Now, you know how much your system should produce every hour to fulfill your daily requirement.

How many Solar panels will you need?

When you purchase solar panels, you should first ask for the wattage of that panel.

To determine the exact number of solar panels, divide your average hourly electricity requirement by the wattage of 1 solar panel that you want to purchase.

That is, 

Number of solar panels = Average hourly wattage requirement /Wattage of 1 Solar Panel

For Example:

As a rough estimate, let’s assume that you purchased 310 Watts solar panel.

And, your average hourly wattage requirement is 8000 Watts. 

Then, the number of solar panels 

= (8000 /310)watts

= 25.806

= 26 solar panels (approximately)

You would need 26 panels if you want to completely eliminate your electricity bill.

Also, if you want to cover your electricity usage partially with solar energy, then you would need fewer panels.

Best Angle and direction for your solar panel

PV panels perform at their best when sunlight is falling straight at its surface.

However, the sun is never stable and thus, it is not possible for us to get the sunlight falling straight on the surface of panels all day.

So, what’s the mid-way?

You can tilt and face your panels to an appropriate position to help them to produce maximum energy as they are exposed to the highest intensity of sunlight for the greatest period of time.

In short, the general rule for solar panel placement is that solar panels should face true south (or geographical south).

in the second place, the general rule for optimal annual energy production is to set the tilt angle of your solar panel equal to your geographical latitude

Let’s say If you are living in Brussels, a city having a latitude of 50°, then you have to tilt your solar panel 50° from the ground.

Latitude vs Tilt graph

Above is the data from EIA showing U.S. utility-scale fixed-tilt solar photovoltaic capacity tilt angle.

Also, you can do seasonal adjustments to get more electricity production. We have also covered it in our previous blog.

Which solar panel to choose?

The total energy production by your solar panel is also affected by the type of panel you will choose.

Solar panels are made of semiconductor materials like Silicon.

The efficiency of the solar panel varies depending on the purity of semiconductor material used in the manufacturing of solar panels.

Monocrystalline solar panels are considered the most efficient panels in terms of electricity generation. 

Monocrystalline Solar Panels
Monocrystalline Solar Panels

Polycrystalline panels are also used to get the budget-friendly installation of solar panels.

Polycrystalline Solar Panels
Polycrystalline Solar Panels

Also, there are many other new technologies in solar panels that claim to be more efficient than ordinary panels like Bi-facial solar panels and  Spinning solar panels.

FAQs

Q. What is Net-Metering?

Ans. Net metering is a kind of billing mechanism that allows you to transfer your excess electricity to the grid.

When your total electricity generation is greater than the electricity you consume. Then, you can also earn by transferring the extra electricity to the grid.

Q. Do my solar panels produce power when the sun isn’t shining?

Ans. Since there is no access to sunlight at night. Thus, solar panels do not produce electricity at night.

However, these do produce electricity on cloudy and rainy days but with less efficiency.

Q. How long will my solar panels last?

Ans. Generally, the solar panels last about 25-30 years.

Q. Which battery should I use for battery backup?

Ans. The most commonly used batteries are:

1. Lithium-Ion Batteries 
2. Lead Acid batteries

Lithium-Ion batteries have a longer expected lifespan in comparison to the Lead Acid batteries.

Q. What are the different types of solar panels?

Ans. There are various types of panels available in the market. 

The three main types of solar panels are:

1. Monocrystalline solar panels
2. Polycrystalline solar panels &
3. Thin-film solar panels

Conclusion

I have discussed all the factors that determine your solar panel requirement. I hope you have got the answer to how many solar panels do you need. 

Even, if you contact a solar power provider to install the system, you have enough information to ask the right questions to your provider. 

Also, you should not forget to test your solar panels before installing them. By doing this, you can ensure that you don’t waste your time installing panels that you’ll have to take down and fix.

I suggest you to follow our Instagram handle @Solar.Funda, where we post regular updates on the latest solar technologies, environmental news & much more.

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Keerti Bhatnagar

Keerti is a tech geek with a vision to save the environment. She is from Uttarakhand, India. And, She is currently pursuing her MCA from G.B. Pant University of Agriculture and Technology, Pantnagar.

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22 Responses

  1. Maritime Meg says:

    Wow! This is really interesting – a lot of great facts about solar power that I never knew about before. I have a lot less daily light as I’m on the northern east coast, so probably a lot more panels. Great article!

  2. Krista says:

    I have no knowledge of solar panels at all, so this was an informative piece for me to read!

  3. Megan says:

    This is really interesting. I was actually thinking about getting solar panels on my house and trying to do my bit so this is super useful!

  4. This is a great guide! We have been thinking about getting solar panels.

  5. Renata Green says:

    Love this! Solar panels are such a great way of collecting power – we need as much alternative energy as we can get to improve our environment.

  6. Renee says:

    What a great way to save money and get back in this big beautiful world. Thanks for the great tips

  7. Maysz says:

    Solar panels are very useful nowadays and I’m looking forward to buy this on my house. very informative post!

  8. Learn something interesting about solar panels, too bad that I live in an apartment that it’s not up to me to change the electric system – But I think the information will help a lot of people. – Knycx Journeying

  9. Agnes says:

    Since the pandemic started our electricity consumption doubled as most of our time were spent at home. We are considering installing solar panels at home.

  10. Mary says:

    Thanks for all of the great information about solar panels. I live in the Northeast, so I would need a lot!

  11. Sarah B says:

    Amazing information. I have so much to learn about solar panels.

  12. Michele says:

    This is really interesting. I would love to eliminate my electric bill. I never knew you could go full solar panel and do that.

  13. Mila R says:

    I exactly needed this. All my neighbors in Miami have solar panels already, but me.

  14. Blair Villanueva says:

    Having a solar panel is the best that we have at home especially during the summer. We only pay low electricity, and we supply a lot of energy back to the power company. I love it!

  15. Lyosha says:

    great guide! It’s never easy to properly could and realize how much items you need not to overspend money

  16. Nkem says:

    Great to learn about solar panels and how they are used. Thanks for sharing!

  17. Kenneth says:

    i have a close friend that do this kind of business….but im quite reluctant he gives me an estimate and its costly….i wander if its till can power up appliances during rainy season here…the sun doesnt shines a lot during july to november…

  18. Eric Gamble says:

    Wow, that is some crazy math. From what I gather, I would need about 24 – 26 panels and that just seems like a lot for my roof. It would have to be a dramatic reduction in costs to the electric bill for me to blanket my roof with so many panels

  19. Monidipa says:

    One of my favorite topics to discuss but the business idea looks great..

  20. Rochelle says:

    So interesting to read, so many persons are starting to go off the grid and using natural resources to save money. I know someone who uses both electricity and solar power in their house and it saves them so much.

  21. Marjie Mare says:

    My husband was just telling me that we should think about investing in solar panels next year. I will share that post with him later, which will help us a lot. Thanks for sharing.

  22. thanks so much for sharing this informative post about solar system, as a go green supporter I am supporting the solar usage. cheers, siennylovesdrawing

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