Not All Roofs Are Suitable For Solar Panels
Apart from estimating how many solar panels you need, you should also consider the weight of the panels themselves.
On average, a single panel weighs around 40 pounds, adding around 2.8 pounds per square foot for a typical pitched roof and 5 pounds for flat roofs. Therefore, you need to make sure that your roof can support this added weight. You also need to consider the material, age, and structure of your roof.
According to the National Renewable Energy Laboratory of the U.S. Department of Energy, approximately 50% of homes cant support rooftop solar panels. Community solar programs are a common way for many homeowners, businesses and renters to go solar without actually installing anything on their roof. Participants can subscribe to a nearby solar farm and pay a lower price for the electricity sourced from it. Through Community Solar with Nexamp, the process is similar to determine the size of a subscribers share of a solar farm is similar to determining the number of rooftop solar panels. We simply analyze a subscribers last 12-13 months of energy usage and recommend a suitable allocation of our farm for them to subscribe to at a discounted rate. The end goal is to offset as much of a subscribers annual electricity costs as possible.
How To Compute The Roof Space
You need to compute the roof space for determining how many solar panels the roof can accommodate. The following steps explain how to calculate your roof space.
Step 1
The first step is taking three critical measurements of the roof.
- Height of the highest point of the roof to the Joints
- Distance of the joint from the horizontal apex till the roof`s eaves
- Length of the roof`s peak
Step 2
Once you have all the three measurements ready, workout the following formula,
A^2 + B^2 = X^2
X is the distance between the apex and the edge of your roof.
Step 3
In this step, you need to use the value of X obtained in step 2 to compute the roof area.
Area of Roof = C x X
The roof area is the total area available to accommodate the solar panels to be installed. In general, it is recommended to deduct 30 Cms from the result of the above computation, and this is done to ensure that you dont include the roofs edge where the solar panels cannot be installed.
Fast Payback On Additional Kws
The cost of increasing the size of the system to 5kW is only $657 per kW. If we assume that you receive a feed-in tariff of 11.1c for every kWh you export back to the grid, it will only take 4 years to pay back the extra 2kW this is assuming that all of the additional solar power output is exported back to the grid. If you self-consume the power, it will pay back much faster. You can expect the panels to continue generating solar power for another 20 years.
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Okay But What About Shade
The shade is, of course, the ultimate enemy of solar. Even a perfectly facing South roof at a 36 degree pitch will be totally undone by shade. But what is too much shade?
Ideally, your roof should get full sun between 9 AM and 3 PM all year round. Many people think their roof is sunny all day, but have you really looked at it multiple times throughout the day? Not surprisingly, if you havent you are not alone. So to do this test your best bet, when youre home for an entire day, is to check your roof each hour and record how much sun is shining on it. Better still, do it a few times throughout the year. After all, 40% of your solar production comes during the winter, so summer is not the only season that matters and your shade may be vastly different in different seasons.
The below graphic of where the sun is in the sky during different seasons tells you why it can be different:
The Size Of Your Roof
Your roof size certainly affects your physical capability to set up your solar panels. Nonetheless, while its possible to begin with the optimal number of panels that will fit on your roof, consider going over your requirements and decide according to your budget.
Computing your roof size requires knowing your houses measurements. To calculate, you can use a measuring tape to gauge along the bottom wall of your building. Alternatively, you may check the original blueprint of your house to obtain a general idea of your roof size or use a solar panel roof size calculator.
Note that you only need to measure the spaces that are appropriate for solar panels. For instance, if you prefer to set up solar panels on the south section of your house, measure the roofs length along the south side. From there, you can measure the east side from the corner to the end of the roof or, around 50% of your wall.
We strongly recommend installing the solar panels in an obstruction-free spot and on a south-facing roof with a 40-degree pitch.
If this is not feasible, you could still obtain money from panels assembled in other directions or on other roof types.
You only need to multiply the measurements of each wall to acquire the total size of your house. For example, if your south-facing roof measures 3.4 x 5.8 meters, you have a roof space amounting to 19.72 square meters.
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Factors In Determining How Many Solar Panels You Need
A critical step in getting a solar installation is calculating the size of your system that you need. This is critical in determining how many solar panels you need to install.
This calculation involves not only your roof area but also your budget. Size and types of solar energy systems differ in terms of physical requirements and cost. So it is important to choose what works best for you.
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What Are The Current Limits For Solar Installation
Unless otherwise specified, states and territories give automatic approval to rooftop solar power panels systems that comply with the Australian standard for solar installation: 5 kW or under. In most states and territories, there is automatic approval given to any solar system up to 5 kW. However, this is in not set in stone.
For example, in May 2017 the Queensland Government changed the regulations for solar installation limits. Automatic approval for rooftop solar used to stop at 5 kW, but the new rules give approval for up to 10 kW.
Battery proviso
The proviso is that you are not permitted to have a battery system capable of feeding power into the grid. The government was fearful of a blowout in their feed-in tariff budget, which originally did not allow for batteries. Feeding power into the grid from batteries during the night woud prove too costly for its feed-in tariff scheme.
The AS/NSZ 4777 standard allows most networks to allow system sizes on a single phase connection up to 5 kW. Three phase connection size is up to 30 kW.
As long as your rooftop solar power panels system meets the requirements the requirements of your network, you will have no problem getting pre-approval.
But you should speak with your solar installer about what you can and cant do. For example, in Western Australia, some electricity retailers allow the installation of rooftop solar depending on which town you live in and provide a handy calculator.
State by state comparison
ACT
Energy Usage And Production
Once you know the number of solar energy panels you can fit your roof, you need to find out how much energy your system will produce and how much electricity you consume. This will help you determine the amount of solar power you will have in surplus or deficit compared to your energy needs.
To do this, check your homes annual energy usage on your electricity bill. For example, the average annual consumption of residential utility customers in the US in 2019 was 10,649 kilowatt-hours, with an average monthly consumption of 877 kWh.
However, your usage can vary depending on the number of people in your home, how many appliances you have, and the season.
Another factor you need to watch out for when finding out how many solar panels you need is the energy production of solar panels. Different solar panels produce varying amounts of electricity. If you choose lower efficiency panels, you need to purchase more panels to cover the energy production amount.
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How Many Solar Panels Can You Have On Your Roof
You may be wondering if there is a limit on the number of solar panels that you can install on your roof. There is no limit on the number of solar panels that you can have on your roof, however in some cases, there may be a limit on the amount of solar power you can generate.
This is due to utility companies limiting the amount of electricity that can be generated by a grid-tied solar system. It is important to be aware of any limitations you may face prior to installing solar panels to ensure that you install the amount necessary to generate a certain amount of energy rather than just installing them when you are uninformed.
How Much Rooftop Solar Power Can You Install A State By State Guide
There are limits to the size of the solar panel system you can install on your rooftop. Naturally, there is only so much weight your roof can support! But a less obvious limit sets how much energy your rooftop solar power panels system is permitted to generate.
Large increase in rooftop solar installation reduces power bills for Australian consumers. Image: Pixabay
This figure varies. Your electricity retailer imposes restrictions on solar power capacity depending on where you live in, sometimes even which town you live in!
These two factors, the number of solar panels and their power output are also subject to how much clean energy you want to generate for home or business use.
Lets look at the factors involved in limiting your solar power while exploring the levels of energy you can achieve in your area.
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Factors To Consider When Determining How Many Solar Panels You Need
When determining how many solar panels you need, its important to start by thinking about what your goals are and why you want to go solar in the first place. Do you want to maximize your return on investment? Do you want to save as much money as possible? Do you want to reduce your upfront costs? Do you want to have the biggest environmental impact and reduce your carbon footprint as much as possible? Most people want a balance of these goals, and may have other priorities as well, so its helpful to get a clear idea of what your specific end goals are before you start designing a solar power system.
Once you have your goals in mind, then you can determine how many solar panels you need to get there. This calculation is going to depend on how much energy your family uses, how much roof area you have available for solar panels, the location of your home and the angle of your roof, how much sunlight shines in your part of the country, the efficiency of the solar panels youre using, and if your local utility offers net metering. Plus, you also need to consider your budget, because a large solar power system might produce more energy, but its going to cost more for the initial installation as well.
Here are a few things you should think about when determining how many solar panels you need for your roof.
Is My House A Good Candidate For Solar Panels
If you’re thinking about going solar, you’re probably wondering: Is solar cost effective? Is my roof suitable for solar panels? Will solar energy generate enough electricity to power my home? Who makes the best solar panels?
But first, it’s important to explore if solar panels for your home make sense. Here are some key questions we ask anyone interested in buying or leasing a solar energy system to make sure their home is best suited for making power with solar panels.
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Code Compliance And Safety Standards
The majority of solar panel warranties require an assembly process done by a licensed and trained professional. So, if you set up the solar system on your own, the warranties will become invalid.
As a result, in case theres damage during the assembly process, or theres an issue with the way the equipment was engineered, youre unlikely to obtain any compensation.
Whats more, building permits and other accompanying regulations are complicated to follow if youre not acquainted with them. Its worth mentioning that you must complete all the paperwork correctly to avoid having the project rejected.
A Few Considerations Before Calculating The Solar Panels:
Calculating the maximum size of an installation for your home is an excellent first step because it will show you what is and is not possible. This estimate considers roof size and budget, and itll simply show you what youve got to work. So, you can make extra options depending on those parameters.
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How Do You Make Space For Additional Solar Power
After determining the houses energy needs, if your roof space cannot accommodate enough solar panels to support it, you can choose either of the two options.
- Reduce the energy needs by switching to a more energy efficient lifestyle, choosing better point-consuming equipment, and not wasting much energy.
- If you are hesitant about making the lifestyle change, you can simply mount your panels on the ground instead of the roof. While this has its pros and cons, it can at least cater to the energy requirements.
The Time To Go Solar Is Now
Sunrun will ensure that you have the best number and style of solar panels to optimize your rooftops solar power production. You can rest easy with a customized solar solution from Sunrun. Our systems are designed for your house structure, lifestyle, energy and financial goals.
We have the resources and experience to maximize your solar systems performance. Well guide you every step of the way from contract through installation and maintenance. And, well be there to support and guide you for many years to come.
Sunrun
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How Many Solar Panels Does My House Need:
Your house solar requirement depends on your average monthly consumption of electricity .
To calculate this have a look into your latest electricity bill there you will find a table that shows your unit consumption in the last one year.
Once you find your annual power consumption data then follow the steps below.
- Take average of yourmonthly consumption that will be your monthly average consumption..
- Then divide this average unit consumption by monthly solar generation from 1 kW system, this should give you your housesolar requirement in kW. .
- Then divide this kW of solar with wattage of one solar panel,you will get the total number of solar panels your house needs.
Lets see an example, Jasons house last 12 month electricity consumption is 400,300,512,415,300,125,588,452,300,700,500,547 so how many solar panels will Jason need for his house?
- First lets take an average of all the values to get the average monthly consumption, this turns out to be 428 KWH.
- Second step is to divide this monthly consumption by our 1 kW solar panels monthly generation ,this will give us 3.72 kW of solar.
- Third step is to divide this 3.72 kW with wattage of one solar panel . On calculation we get 11.27 ~ 11 or 12 Solar Panels.
There it is Jasons house needs3.72 kW of solar or 12 solar panels each of 330 Wp to offset 90 % of their electricity bill.
Now that you know your solar panels requirement, let us see what is the dimension of one solar panel and area needed to install one solar panel.
Why Are There Limits
So why put limits on renewable energy? Whilst the dream may be to go completely off-grid the reality is that most solar systems are grid-connected. This is so when the sun is not out, and your solar system is not generating any energy your property can still function and run appliances, lights etc. The issue is that when the electricity distribution network was designed it was set up to send electricity in one direction. From the grid to your property. When grid-connected solar came along this one direction electricity became two way with solar homes sending their excess energy to the grid in exchange for a Feed-in Tarif.
The concern network owners have is that too much energy being fed into the grid might cause operational problems and risk disruption to the electricity flow which is why they have set restrictions on the amount of electricity a property can generate.
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How Many Solar Panels Will Fit On My Roof
In the U.S. Solar panels are preferably installed on south-facing roof sections. North-facing roof sections and any areas on your roof that experiences shading is generally avoided.
If the south-facing section of your roof is prone to shading or is simply too small, southwest or southeast-facing sections are the next best bet. If those are also unavailable or non-existent, west and east-facing roof sections are used.
In any case, will give you a pretty good idea of how much of your roof is actually usable for solar panels. All you have to do is submit an address.
Based on 3D modeling of your roof and nearby trees, the tool will estimate how much of your roof is available for solar panels.
The estimate might not be 100% accurate, but it absolutely beats doing all calculations manually, especially if your roof structure is as complicated as the ones shown in the image.
Based on the available space on your roof, the calculator below will estimate the number of solar panels and the size of the system that can fit.
For example, based on the square footage from the example above, that particular roof can fit as much as 84 solar panels. Which is equivalent to 25.2 kW of solar power:
Chances are the available space on your roof is more than enough to install all the solar power you need. A better approach would be to determine how much solar power you need first.
Another important thing to mention is Fire Setback codes.
