Solar Panel Size Guide

Solar Panel Size Guide: How many solar panels do you need?

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The size of a solar panel is a huge determining factor for placement, production and optimization. In our solar panel size guide, we will highlight everything you should know about your solar panel sizing and possible power output.

Solar Panel Size Guide: How many solar panels do you need?

Whether you are looking to cover your whole rooftop with solar panels or just a portion of it, you might be wondering about solar panel size and possible power output, right?

The usual language in the solar panel involves watts and volts, but in reality, solar panels take up how much space?

Well, to start off, it is important that you know that by size you could be referring to the physical dimensions of the panel or the power output in volts or watts.

In terms of dimensions, you should care about the size of solar panels especially is your roof space is small or uncommonly shaped.

A plain long roof will allow you to buy larger and cheaper panels of lower efficiency to cover your energy needs.

Unusually shaped roofs or with smaller surface will make you play a little more with such numbers.

Aiming to clarify that, here’s a review on solar panel size that could come in handy for you.

Solar panel size dimensions

If you refer to the physical solar panel size dimensions, we can start off by saying that each manufacturer has its own optimal dimensions. This largely depends on their own technology.

As you might already know, solar panels are comprised of an arrangement of cells. Depending on the number of cells in the panel they are larger or smaller.

Traditionally, solar panels come in two different configurations: 60-cell and 72-cell. However, if you go to Panasonic or SunPower, they offer 96-cell panels.

But solar energy does not stop in large rigid solar panels.

You can also find small solar panels, and they are ideal to mount on motorhomes, boats, and caravans. Check out our guide on the best boat solar panels

Solar panels also come in flexible and foldable configurations, making them more practical and easy to carry in case you’d like to take them on your hiking or camping trips.

Length and Width 

The length and width of conventional rigid panels vary slightly from one manufacturer to the other.

Most manufacturers stick to standard sizes, whereas some others come up with their own unique sizes.

The common size dimensions are:

  • 60-cell panels: 39” W x 66” L
  • 72-cell panels: 39” W x 77” L
  • 96-cell panels: 41.5” W x 62.6” L

Depending on the manufacturer, they’ll be, in general, an inch or two larger on either side.

Nonetheless, traditional systems utilize 60-cell and 72-cell panels. These solar panel sizes are standard for residential and commercial installations.

Solar panel size dimension comparison

Smaller sizes are a better fit for residential purposes since smaller panels allow us to maximize the space on the panel installation.

The figure below shows this situation better.

Depth

The depth of solar panels range from 1.4 in. to 1.8 in.

More manufacturers, however, are stepping nowadays onto the 1.8 in. ground.

Weight

This is an important factor to consider when installing a solar PV system on your rooftop.

Each residential solar panel, of those 60-cell ones, weighs about 40 pounds. That number reaches up to 50 pounds for those panels in the range of  72-cells and up.

With these numbers in mind, it is important to check whether your roof structure can withstand such weight.

Go for a structural analysis before making any move with the panels. It is better to make a reinforcement beforehand than having to rebuild your roof.

The number of cells and solar panel size

As you might already know, the cells are the core of a solar panel.

The number of cells determines the output voltage of the panel, but it will also determine the solar panel size.

The more cells in the panel, the bigger the panel and the higher possible output voltage.

From this principle, intuitively you might sense that the 72-cell panel of the figure above, apart from being bigger, will have a higher voltage than the 60-cell one.

So, the more cells are connected in the panel, the higher the output voltage. But, for the voltage to add up the cell must be connected in series.

This is graphically explained in the figure below.

Total output voltage of a system connected in series

How big are solar cells?

Lately, manufacturers started to experiment with different individual solar cells sizes in order to reach higher solar panel efficiencies and performance.

Nowadays, the market is dominated by two solar cell sizes:

  • 5 “ W x 5” L
  • 6” W x 6” L

The 5” are mostly used by Sun Power in their 96-cells panels, making that panel to look like a common 60-cells one.

How many solar panels do I need?

You might be wondering, how many solar panels are needed to power an average house?

Simply answered: It depends. You’ll see why.

Factors that Influence Solar Production & The Number of Solar Panels Needed

There are a few factors that affect the size dimensions of your solar array.

1. Solar Irradiance

First of all, not every place on the planet counts on the same solar irradiance throughout the year. In other words, not every place on the planet receives the same amount of energy from the sun in one year.

Take a look at the image below.

By The World Bank – https://globalsolaratlas.info, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=73047797

The image tells us that, a place in Northern Africa receives more solar irradiance on average per year than, say, Canada. Regardless of the sun shining for 12 hours in the Canadian summer.

This is why you’ve probably heard that covering a small portion of the Sahara desert would suffice to cover the world’s energy needs.

2. Sunlight hours

The amount of sunlight hours your roof will receive also depends on what time of the year it is.

Intuitively you know that your panels will produce more energy during summer than winter, given the amount of peak sunlight hours.

Expect a higher number of peak sunlight hours per year if you are in Florida or California than in New England.

Whereas a home in California needs a system of approximately 7.0 kW system to cover an energy demand of 10,400 kWh per year, a home in New England will require an 8.8 kW system to cover that same amount of energy needs.

So, fellows in New England should opt for more efficient panels in their energy system, or simply increase the amount of panels to cover that energy demand. Check out our guide on solar panel power production to learn more. 

3. Your energy demand

This is akin to asking you: how much power do you use?

If you want to answer this quickly, go get your past energy bills and they will tell you how much energy you use per month.

The energy used is shown as “Kilowatt-hours or kWh used”. Also, check what period this bill corresponds to.

In case your bill does not show your used power, then look for the meter reading at the beginning of the billing period and at the end. Subtract them and Voilá! That’s your power usage.

Also, you should consider how much of your power demand you want to cover with solar.

Maybe you don’t want to cover it all with solar, but instead just a portion of it. That’s possible too.

The average U.S. home energy usage rounds 900 kWh per month, which equals to approximately 30 kWh per day or 1.25 kWh per hour.

4. The climate of your area

Well, as you might imagine, a home in a temperate climate uses less energy than somewhere colder or hotter.

In hot climates, fans do not suffice, and people turn to A/C to have a comfortable temperature around.

So, having the A/C on for most of the day will consume more energy than with a fan, right? So, having A/C at home means that you will need to install more solar power.

A small home in a mild climate area uses around 200 kWh per month. But if you go south where the A/C power demand occupies a large share of the energy consumption, that figure could go up to 1700 Kwh.

Same story goes to heating.

5. Solar panels efficiency

Not all solar panels have the same efficiency. Some convert sunlight into electricity at better rates than others. This single factor will affect the power output of your system.

If you use more efficient panels, you will require fewer panels to cover your needs than if you used cheaper less efficient panels.

However, it also depends on where you are.

If you are in a place with plenty of sunshine throughout the year, probably the efficiency will not play such a determinant role as if you were in the U.K.

For a 10 kW system size using low-efficiency panels, your system will occupy around 612 sq.ft. to cover that energy need. But if you used medium efficiency panels, that number lowers to 508 sq.ft. And for highly efficient panels it reaches down to 448 sq.ft.

See Related: Solar Panel Insurance Guide

6. Some numbers

The average U.S. home uses around 10,000 and 11,000 kWh per year. For the coming calculations let’s take the average, 10,500 kWh.

That is the number you take from your energy bill.

Now, divide that number by the energy production ratio of solar panels. This last number represents the approximate number of kWh/year a set of solar panels will produce according to their location.

For the U.S. that number varies between 1.31 and 1.61. The former is the ratio for Maine and the latter for Arizona.

Then, divide each of those numbers by the wattage of the panels. For this calculation, let’s assume 250 Watts per panel. You can play with different wattages so you check the difference.

With those two numbers, an average U.S. home will need between 33 and 26 solar panels of 250 watts.

These rough calculations show how the mentioned factors affect the number of panels needed to cover 100% of your energy demand.

If you use panels of higher wattage, for instance, a 280 watt one, then those numbers decrease to 28 and 23 panels respectively.

The power output size

Not all solar panels are the same.

Those solar panels used for residential purposes range from 150 watts to 370 watts per panel, depending on the panel size efficiency and cell technology.

Small solar panels

Small solar panels traditionally come in three common sizes: 50 watt, 100 watt and 160 watt. Yet, you can also find panels of 150, 160 or 175 watts.

As mentioned before, each manufacturer has its own solar panel sizes and wattages sweet spot.

In the table below, we give you a comparison of approximate solar panel sizes and wattage for small solar panels. In addition, we include the flexible solar panels as a comparison.

Wattage

(W)

Width

(in)

Length

(in)

Voltage

(Volt)

502126

12

100

2147

12

1602658

12

Flexible panels

50

21

26

12

1002148

12

1602655

12

 

Solar panels for residential and business use

In general, the rooftop space in homes is smaller than in businesses and companies. For this reason, the panels used in residential applications are those of smaller sizes.

Commercial and industrial applications do not have a space limitation and can afford to go for larger panels.

The following solar panel size chart lists the commonly used solar panels size for residential and business uses.

Solar cells per module

Length

(in)

Width

(in)

Depth

(in)

Area

(sq. ft.)

Wattage

60

65391.517.7

175 – 240

7278391.521.2

250 – 300

These are some of the best solar panels to buy

Solar panels for commercial businesses

For businesses, solar panels might represent an environmental good or a financial strategy.

Whatever the reason could be, solar panels are a great move for all sizes of businesses.

Just as in residential cases, the size dimension of your system will be determined by the same factors listed in the how much power do I need section. And the size of solar panels for commercial businesses are just the same as the ones we mentioned above.

Nonetheless, since businesses require on average more power than homes, the typically used solar panel size in businesses is 72-cells size or more, like that of 96-cells.

The difference lies in the size of the solar panel array, given that the power demand for commercial businesses is higher than for residential use.

The figure below illustrates an approximation of that comparison.

Businesses systems occupy larger rooftop space than residential ones, given that companies’ energy needs are higher

An average home fits its energy needs with systems of around 6 kW or 7 kW. Businesses will require larger systems. In this case, expect to occupy a larger rooftop surface to cover your company’s energy needs.

If you install a 6 kW system with, say, 20 average-sized solar panels, expect to occupy a surface of 27 ft. wide by 13 ft. long on your rooftop.

The table below shows a rough idea of the common size of solar panels for commercial businesses and the expected price range

Common system sizes for commercial businesses and expected price range.

System size

 (Kw)

Expected Price Range* (USD)

25

43,750 – 56,350

50

87,500 – 112,700

100

175,000 – 225,400

250

437,500 – 563,500

*Price range with 30% federal income tax credit for solar deducted

Related Resources

Green Coast is a renewable energy and green living community focused on helping others live a better, more sustainable life.

We believe that energy and green living has become far too complex, so we created a number of different guides to build a sustainable foundation for our future.

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