How Many Solar Panels Would I Need

Determine The Daily Sunlight Average In Your State

As weve mentioned, the amount of sun hitting your roof can determine how many panels you could need. To ballpark this figure, find the average daily peak sunlight hours in your state. We used North Carolina, POWERHOME SOLARs headquarters, for our example.

North Carolina receives an average of 4.71 hours of daily peak sunlight.

Average Solar Panel Output

Most solar panels produce 250 watts per hour, but this can range anywhere from 150 watts to 370 watts per hour depending on the brand. Panels with higher efficiency will cost more but are also of a higher-quality build than their less-expensive counterparts. Solar panels can degrade in efficiency by about 0.8 percent each year, according to a 2012 study by the National Renewable Energy Laboratory . Once you calculate solar panel wattage you expect to produce for your entire system, youll have a better idea of how bi your system should be.

How Does Solar Energy Work

Our sun is a natural nuclear reactor. It releases tiny packets of energy called photons, which travel the 93 million miles from the sun to Earth in about 8.5 minutes. Every hour, enough photons impact our planet to generate enough solar energy to theoretically satisfy global energy needs for an entire year.

Currently photovoltaic power accounts for only five-tenths of one percent of the energy consumed in the United States. But solar technology is improving and the cost of going solar is dropping rapidly, so our ability to harness the sun’s abundance of energy is on the rise.

In 2017,the International Energy Agency showed that solar had become the world’s fastest-growing source of power marking the first time that solar energy’s growth had surpassed that of all other fuels. Since then solar has continued to grow and break records around the globe.

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System Size Based On Daylight Electricity Use

The average Australian household consumes 18kWh of electricity each day. If we use a house in Adelaide as an example, you would need a 5kW solar system to generate this amount of power. However, if the household only consumes 40% of its electricity during daylight hours, there is no point in installing such a large system. In this instance, a system that generates on average 7.2kW of electricity per day would be sufficient. Therefore, a 3kW system is likely to deliver the most affordable solution.

Design And Permitting Phase

Once all of the information and measurements have been gathered in Step 2, the solar installer will create a solar engineering and site design plan. The plan will include the number of panels and where they’ll be placed on your roof, the wiring of the system and how it will be interconnected with the utility. The design plan should also ensure compliance with local fire safety requirements. The installer will then submit these plans to your city/county permitting departments and to your utility company. Unfortunately, most cities, counties and utilities have different requirements that can vary greatly and can be confusing, even for solar pros. Make sure you find an installer who is familiar with the local building codes and the local utility companies.

The design and permitting phase typically takes approximately one to three months, depending on the jurisdiction. Your installer should keep you informed about the progress and let you know when it’s time to schedule the physical installation date.

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How Many Solar Panels Will I Need

Every household is unique and theres a good chance youll require something a little different compared to the average American home.

To determine how many solar panels you need specifically, you need to have some clear goals in place and have a good idea of what your current situation looks like.

When thinking about your goal for solar, ask yourself what exactly it is youre trying to achieve. Do you want to put solar in to increase the value of your home?

Do you want to save as much money as possible from your energy bills? Do you want to do your part for the environment and reduce your carbon footprint? Do you want to totally go off the grid and only rely on solar power to run your home?

The answer to these questions will give you a good indication of how many solar panels you need.

The average persons goals are to do their part for the environment while saving themselves money, so with that in mind, we can then move onto the important questions to determine where to go next.

Calculating The Size Of Your Solar Pv System

Now you know how much power you typically use and the times of day you use it. What capacity will your solar PV system need to be to cover your power usage?

First, we’re assuming you’ll have a grid-connected system. This is by far the most common type and it simply means you have solar panels generating electricity during the day, and a grid connection to supply electricity when the solar panels aren’t generating enough . See grid-connected vs off-grid for more.

How much electricity can you expect per kW of solar panels?

Solar PV systems are rated in watts or kilowatts . You’ll see systems described as 4kW, 5kW, 10kW and so on.

1kW of solar panels = 4kWh of electricity produced per day .

For each kW of solar panels, you can expect about 4kWh per day of electricity generation. So a 6.6kW solar system will generate about 26.4kWh on a good day .

It’s just a general rule the actual amount of electricity generated per kW of solar panels depends on your location, the time of year and the amount of sunlight you’re getting, the quality of the system, the orientation of the panels, how old they are, and so on. In southern regions such as Hobart it could be as low as 3.5kWh per day, while the same 1kW of panels in Darwin could generate 5kWh.

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Factor #: Your Home Energy Goals

The next factor in your solar system size is the goal of choosing clean solar energy for your home. There are lots of reasons why homeowners are choosing to go solar across the world, and whatever your reason, its a great one.

Reducing your monthly electricity bill is a pretty common reason, or being fed up with your utility company. Another great reason is the fact that the price of electricity is continuing to rise every year. Or how about the fact that fossil fuel energy is running out and is horrible for the environment. If your goal is clean, sustainable energy that cuts down on carbon emissions, youre not alone. More and more every day, legislation, businesses, and homeowners are starting to turn to clean energy.

If one of your goals is to reduce your electricity bill, the size of your system can make a big difference. For some homeowners it can mean thousands of dollars in savings every year. Make sure to discuss your goal and how much of your homes energy consumption youre expecting your system to produce.

Learn more about net metering.

What you need for your appointment:

Bring a list of your homes energy goals when you meet with your Solar Energy Specialist. They can help you understand what this means in terms of how many solar panels are needed for your home.

Target A Solar Power Production Goal

Now that you have calculated how many kWhs are currently being usedfactor in any adjustments based on foreseen changes to your electricity consumption. You can either have this as an annual breakdown of kilowatt-hours, monthly or daily usage.

Based on your recent utility bill, it may show that you are currently using 6,000 kWh annually. This number can then calculate a monthly average of 500 kWh. Or a daily average of 16.5 kWh . This quick calculation will tell you how much energy your solar energy system should offset to determine how many solar panels you will need to offset that solar power production goal.

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Consider How Long Youll Stay At The Cabin

Now that we have a good idea of how much power well use when were at the cabin, we need to think about how long we generally stay there. If you use the cabin an average of 2 days per week, then you dont need as much solar capacity as you would if you use it 6 days per week. That is, assuming you have sufficient power storage. So now we need to figure out how much power is going to be used while were not there.

There may be some things you want to keep running while youre away. Maybe you go to the cabin weekly and like to store some food in the refrigerator. Maybe you like to keep the furnace on at a low temperature setting to keep the water pipes from freezing. Whatever it is, we need to figure out how much power we use when were not there.

Go through the same process that we outlined above. Add up the usage for all of the things you want to keep running while youre away.

Now lets add up our power usage per week. If were there 2 days and away 5, then well take 2 times our usage while at the cabin plus 5 times our usage while away. That gives us weekly power usage.

For example, if we use 20 kWh per day while there and 5 kWh per day while away, we take + = 40 + 25 = 65 kWh per week. Well, thats an average of just under 10 per day. So as long as I have enough battery storage to get me through the 2 days per week Im there then I can actually install a system that puts out more like 10kWh per day.

How Much Power Does Your Home Need

Once you know how much energy you’re using over the course of a year we can begin to work out how many solar panels you’ll need.

The power output of solar panels is measured in watts and can range from around 245W right up to 400W.

If your home has a particularly high demand for electricity then it makes sense to consider solar panels with a larger power output more than 325W. Investing in solar panels with a higher output will not only mean they generate more energy, you will need less of them.

To reach the UK average energy usage of 3,800 kWh, only 10 400W solar panels would be needed as part of the solar PV system, whereas 16 250W solar panels would be needed to achieve the same output.

It’s worth noting that you don’t need to install a solar system that meets your entire demand for electricity. A solar system can also subsidise part of your energy usage, which will help to reduce energy bills and your carbon footprint but mean that you still have a fair amount of reliance on your energy supplier .

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Putting It All Together

With those variables in mind, we can roughly estimate the number of solar panels for home that you’ll need. In this example, we’ll use the average annual energy consumption, solar panel wattage and hours of sunlight that we mentioned earlier.

Let’s say that your property receives four hours of sunshine each day, and you’re purchasing 325-watt solar panels. In that case, each panel can generate 1,300 watt-hours per day . Assuming that your energy usage is in line with the average of 29 kWh per day, you’d need 23 325-watt panels to create enough electricity for your home.

How To Size A Solar Array

The term solar array size is used to describe a solar panel systems capacity to produce electricity.

A solar array sized 300 watts can produce 300 watts of electricity, while a solar system sized 6 kilowatts will produce 6,000 watts under standard conditions.

Figuring out what size solar array is right for you depends on several factors such as your energy consumption, available roof space, and the amount of sunlight where you live .

Lets assume you want a solar array big enough to wipe out your electricity bill. In that case, you may want a solar array that can produce 1,000 kWh of electricity a month .

Here are the solar array sizes you would need to produce 1,000 kWh in different parts of the country:

In terms of the number of panels, the solar array sizes above would need between 16 and 26 solar panels – assuming the use of 320-watt panels.

In terms of space, a solar array would require between 277 and 450 square feet.

Utility-scale solar arrays, or solar farms, on the other hand, might be comprised of hundreds or even thousands of solar panels.

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Few Things About Solar Panel Output Efficiency

Solar panel type and quality make a significant difference in terms of solar output and efficiency. Not all solar panels are the same.

For instance, monocrystalline photovoltaic solar panels are known to be the most efficient solar panels on the market, but also the most expensive.

Their two main advantages over the other types of solar panels such as polycrystalline or thin film panels is that 1) they absorb more sunlight than conventional cells and their output efficiency is not affected that much by temperature and 2) they occupy less space. These are an ideal option if you do not have enough roof space for standard panels.

On the other hand, polycrystalline panels are cheaper, they are less efficient and therefore occupy more space, but offer a better return on investment than monocrystalline panels.

Because of these wide differences in quality and efficiency, its up to you to decide which solar panels are right for your home.

The main takeaway is that, the more efficient the panels are, the more power they can produce, and the fewer photovoltaic panels you will need on your roof to get the same energy output as you would get with polycrystalline or thin film solar panels.

Overall, if money is not an issue, monocrystalline panels are the best option.

The Questions To Answer To Calculate Your Solar Needs

Before you call the professionals and have a solar installer out to your house, you can get an idea of what youre going to require to use this type of energy.

Consider these questions to see how many youll need based on your current usage, home setup, and future goals, to get a rough estimation of the type of solar setup you require.

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Where Do I Get A Quote

You can start looking for quotes from solar contractors by reaching out to your local library or utility company, who may have lists of companies you can contact. You might be surprised at how many different types of people are in the industry! Theres also an app that lets you compare prices from multiple installations in your area.

How Much Battery Do You Need

Without any doubt, solar power is not the only important factor for you to think through for off-grid energy. The battery power is also a valuable factor that needs your attention. As you might already know, solar power works solely when the sun is out.

So, this implies keeping extra batteries in your recreational vehicle to conserve energy overnight is paramount. Deciding on how much battery you have will be up to you. Nonetheless, a minimum of a 24-hour worth of stored energy is highly recommended.

Fundamentally, there are two different types of batteries that you could choose from, lithium batteries and lead deep-cycle batteries.

• Lithium-ion batteries are adept in many applications and have the price point to prove this.
• Lead deep-cycle batteries are less expensive however, they are prone to get damaged quickly, especially if youre not well aware of their limitations. Remember that you must not allow lead deep-cycle batteries to get below half charge as this condition will bring severe and permanent damage.

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How Long Do Solar Panels Last

In short, a quality solar panel can last up to 25 years or even longer. Solar panels are designed to live a long life in the elements outside.

Your typical solar panels come with a warranty that lasts 25 years, so you are guaranteed to reap the benefits for quite a long time.

According to a study conducted by the National Renewable Energy Laboratory, solar panels last 80% longer than their warranty.

This can save you thousands on utility bills down the road!

Can You Run A Washing Machine On Solar Power

Some washing machines are actually designed with a solar kit installed and can be hooked up to your system. Theres also the option of installing an outdoor clothesline for drying laundry between cycles or using a dryer that runs on electricity generated by renewable sources like solar power. A third option is running off-the-grid where you use battery storage to capture the power generated by your panels, so that you can use it anytime.

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How Many Solar Panels Do You Need For Specific System Sizes

In our long example at the beginning of this piece, we determined that an 8 kW system would probably cover the average energy use for an American household if you live in an area with a production ratio of 1.6, which might be a realistic number for homes in most parts of California. Lets extend that a little further, and look at a few more examples. In the table below, weve compiled some solar panel estimates for common system sizes seen on the EnergySage Marketplace. Again, the big caveat here is that were using 1.6 as the production ratio of choice. For California shoppers, this might actually be realistic, but for folks in the Northeast or areas with less sun, these estimates might be a bit high on the production end and low on the number of panels needed.

How many solar panels do I need for my house? System size comparison